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Popov, V., Marevic, I., Rummel, J. & Reder, L. (in press). Forgetting is a Feature, not a Bug: Intentionally Forgetting Some Things Helps Us Remember Others by Freeing up Working Memory Resources. Psychological Science.
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    • We used an item-method directed forgetting paradigm to test whether instructions to forget or to remember one item in a list affects memory for the subsequent item in that list. In two experiments, we found that free and cued recall were higher when a word-pair was preceded during study by a to-be-forgotten (TBF) word pair. This effect was cumulative – performance was higher when more of the preceding items during study were TBF. It also interacted with lag between study items – the effect decreased as the lag between the current and a prior item increased. Experiment 2 used a dual-task paradigm in which we suppressed either verbal rehearsal or attentional refreshing during encoding. We found that neither task removed the effect, thus the advantage from previous TBF items could not be due to rehearsal or attentional borrowing. We propose that storing items in long-term memory depletes a limited pool of resources that recovers over time, and that TBF items deplete fewer resources, leaving more available for storing subsequent items. A computational model implementing the theory provided excellent fits to the data.
Vogt, K. M., Norton, C. M., Speer, L. E., Tremel, J. J., Ibinson, J. W., Reder, L. M., & Fiez, J. A. (2019). Memory for non-painful auditory items is influenced by whether they are experienced in a context involving painful electrical stimulation. Experimental Brain Research, 341891. https://doi.org/10.1007/s00221-019-05534-x
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    • In this study, we sought to examine the effect of pain on memory. Subjects heard a series of words and made categorization decisions in two different contexts. One context included painful shocks administered just after presentation of some of the words; the other context involved no shocks. For the context that included painful stimulations, every other word was followed by a shock and subjects were informed to expect this pattern. Word lists were repeated three times within each context in randomized order, with different category judgments but consistent pain-word pairings. After a brief delay, recognition memory was assessed. Non-pain words from the pain context were less strongly encoded than non-pain words from the completely pain-free context. An important accompanying finding is that response times to repeated experimental items were slower for non-pain words from the pain context, compared to non-pain words from the completely pain-free context. This demonstrates that the effect of pain on memory may generalize to non-pain items experienced in the same experimental context.
Popov, V., & Reder, L. (2018). Frequency Effects on Memory: A Resource-Limited Theory. http://dx.doi.org/10.17605/OSF.IO/DSX6Y
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    • We present a review of frequency effects in memory, accompanied by a theory of memory, according to which the storage of new information in long-term memory (LTM) depletes a limited pool of working memory (WM) resources as an inverse function of item strength. We support the theory by showing that items with stronger representations in LTM (e.g. high frequency items) are easier to store, bind to context, and bind to one another; that WM resources are involved in storage and retrieval from LTM; that WM capacity is greater for stronger, more familiar stimuli. We present a novel analysis of preceding item strength, in which we show from eight existing studies that memory for an item is higher if during study it was preceded by a stronger item (e.g. a high frequency word; HF). This effect is cumulative (the more prior items are HF, the better), continuous (memory proportional to word frequency of preceding item), interacts with current item strength (larger for weaker items) and interacts with lag (decreases as the lag between the current and prior study item increases). A computational model that implements the theory is presented, which accounts for these effects. We discuss related phenomena that the model/theory can explain.
Delahay, A.B. & Reder, L.M. (2018). Short-term memory. In Frey, B. (Ed.), The SAGE Encyclopedia of Educational Research, Measurement, and Evaluation. Thousand Oaks, CA: Sage Publications. http://dx.doi.org/10.4135/9781506326139.n628
Liu, X., Tan, D., & Reder, L. (2018) The Two Processes Underlying the Testing Effect---Evidence from Event-Related Potentials (ERPs), Neuropsychologia, ISSN 0028-3932. http://dx.doi.org/10.1016/j.neuropsychologia.2018.02.022
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    • Theoretical explanations of the testing effect (why people learn better from a test than a re-study) have largely focused on either the benefit of attempting to retrieve the answer or on the benefit of re-encoding the queried information after a successful retrieval. While a less parsimonious account, prior neuroimaging evidence has led us to postulate that both of these processes contribute to the benefit of testing over re-study. To provide further empirical support for our position, we recorded ERPs while subjects attempted to recall the second word of a pair when cued with the first. These ERPs were analyzed based on the current response accuracy and as a function of accuracy on the subsequent test, yielding three groups: the first and second tests were correct, the first was correct and the second was not; both were incorrect. Mean amplitude waveforms during the first test showed different patterns depending on the outcome patterns: Between 400–700 ms the amplitudes were most positive when both tests were correct and least positive when both were incorrect; mean amplitudes between 700–1000 ms only differed as a function of subsequent memory. They were more positive when the second test was correct. Importantly, the later component only predicted subsequent memory when the answers were not overlearned, i.e. only correctly recalled once previously. We interpret the 400–700 ms time window as a component reflecting a retrieval attempt process, which differs as a function of both current and subsequent accuracy, and the later time window as a component reflecting a re-encoding process, which only involves learning from tests, both of which are involved in the testing effect.
Shen, Z., Popov, V., Delahay, A., & Reder, L. (2018). Item strength affects working memory capacity. Memory & Cognition, 46(2), 204-215. http://dx.doi.org/10.3758/s13421-017-0758-4
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    • Do the processing and online manipulation of stimuli that are less familiar require more working memory (WM) resources? Is it more difficult to solve demanding problems when the symbols involved are less rather than more familiar? We explored these questions with a dual task paradigm in which subjects had to solve algebra problems of different complexities, while simultaneously holding novel symbol-digit associations in WM. The symbols were previously unknown Chinese characters, whose familiarity was manipulated by differential training frequency with a visual search task for nine hour-long sessions over three weeks. Subsequently, subjects solved equations that required one or two transformations. Before each trial, two different integers were assigned to two different Chinese characters of the same training frequency. Half of the time, those characters were present as variables in the equation and had to be substituted for the corresponding digits. After attempting to solve the equation, subjects had to recognize which two characters were shown immediately before that trial and to recall the integer associated with each. Solution accuracy and response times were better when: the problems required one transformation only; variable substitution was not required; or the Chinese characters were high frequency. The effects of stimulus familiarity increased as the WM demands of the equation increased. Character-digit associations were also recalled less well with low frequency characters. These results provide strong support that WM capacity depends not only on the number of chunks of information one is attempting to process, but it also depends on their strength or familiarity.
Manelis A., Popov V., Paynter C., Walsh M,. Wheeler M. E., Vogt K. M., Reder L. M. (2017). Cortical Networks Involved in Memory for Temporal Order. Journal of Cognitive Neuroscience, 29(7):1253-1266. PMID: 28294716
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    • We examined the neurobiological basis of temporal resetting, an aspect of temporal order memory, using a version of the delayed-match-to-multiple-sample task. While in an fMRI scanner, participants evaluated whether an item was novel or whether it had appeared before or after a reset event that signified the start of a new block of trials. Participants responded "old" to items that were repeated within the current block and "new" to both novel items and items that had last appeared before the reset event (pseudonew items). Medial-temporal, prefrontal, and occipital regions responded to absolute novelty of the stimulus-they differentiated between novel items and previously seen items, but not between old and pseudonew items. Activation for pseudonew items in the frontopolar and parietal regions, in contrast, was intermediate between old and new items. The posterior cingulate cortex extending to precuneus was the only region that showed complete temporal resetting, and its activation reflected whether an item was new or old according to the task instructions regardless of its familiarity. There was also a significant Condition (old/pseudonew) × Familiarity (second/third presentations) interaction effect on behavioral and neural measures. For pseudonew items, greater familiarity decreased response accuracy, increased RTs, increased ACC activation, and increased functional connectivity between ACC and the left frontal pole. The reverse was observed for old items. On the basis of these results, we propose a theoretical framework in which temporal resetting relies on an episodic retrieval network that is modulated by cognitive control and conflict resolution.
Liu, X. L., Reder, L. M. (2016). fMRI exploration of pedagogical benefits of repeated testing: when more is not always better. Brain and Behavior. http://dx.doi.org/10.1002/brb3.476
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    • Introduction: The testing effect refers to superior retention when study is fol- lowed by a test rather than followed by another study. Most research to date on why the testing effect occurs has been behavioral, but we employed neuroimag- ing methods in this study in order to shed light on the underlying processes. Methods: Subjects were scanned while studying, restudying, and taking cued- recall tests of word pairs (with no feedback). We analyzed the BOLD responses by back sorting the encoding and test trials based on whether the subsequent test was correct or incorrect. We compared the subsequent memory patterns in ini- tial study, restudy, and test trials. Results: Overall, brain activity during test trials was a better predictor of later performance than brain activity during restudy tri- als. For test trials, we separately examined brain regions associated with the retrieval attempt process during successful retrieval and regions associated with the re-encoding process during retrieval in terms of prediction of subsequent memory. Regions associated with retrieval attempts were found to always predict subsequent memory success (the greater the activation, the more likely the cor- rect recall); however, the regions associated with re-encoding would sometimes predict subsequent failure, specifically when subjects had correctly recalled the associated word several times already. Conclusions: These results suggest that whether a testing effect advantage is observed depends on both on the retrieval process and the re-encoding process which follows that retrieval.
Walsh, M. M., Paynter, C. A., Zhang, Y., & Reder, L. M. (2016). Hitting the reset button: An ERP investigation of memory for temporal context. Brain Research. http://dx.doi.org/10.1016/j.brainres.2015.05.003
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    • This study explored how temporal context influences recognition. In an ERP experiment, subjects were asked to judge whether pictures, presented one at a time, had been seen since the previous appearance of a special reset screen. The reset screen separated sequences of successively presented stimuli and signaled a change in temporal context. A “new-repeat” picture was one that had been seen before but was to be called “new” because it had not appeared since the previous reset screen. New-repeat pictures elicited a more negative FN400 component than did “old” pictures even though both had seen before during the experiment. This suggests that familiarity, as indexed by the FN400, is sensitive to temporal context. An earlier frontopolar old/new effect distinguished pictures that were seen for the first time in the experiment from all other pictures. The late positive component (LPC), which is typically greater for old stimuli, was smaller for new-repeat pictures than for pictures seen for the first time in the experi- ment. Finally, individual differences in task performance were predicted by the differences in amplitude of P3b that was evoked by the onset of the reset screen.
Reder, L. M., Liu, X. L., Keinath, A., & Popov, V. (2016). Building knowledge requires bricks, not sand: The critical role of familiar constituents in learning. Psychonomic Bulletin & Review. http://dx.doi.org/10.3758/s13423-015-0889-1
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    • Despite vast efforts to better understand human learning, some principles have been overlooked, specifically that less familiar stimuli are more difficult to combine to create new knowledge and that this is because less familiar stimuli consume more working memory resources. Participants previously unfamiliar with Chinese characters were trained to discriminate visually similar characters during a visual search task over the course of a month, during which half of the characters appeared much more frequently. Ability to form associations involving these characters was tested via cued-recall for novel associations consisting of two Chinese characters and an English word. Each week performance improved on the cued-recall task. Crucially, however, even though all Chinese character pairs were novel each week, those pairs consisting of more familiar characters were more easily learned. Performance on a working memory task was better for more familiar stimuli, consistent with the claim that familiar stimuli consume fewer working memory resources. These findings have implications for optimal instruction including second language learning.
Dong, S., Reder, L. M., Yao, Y., Liu, Y., & Chen, F. (2015). Individual differences in working memory capacity are reflected in different ERP and EEG patterns to task difficulty. Brain Research, 1616, 146-156. http://dx.doi.org/10.1016/j.brainres.2015.05.003
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    • This study examined whether there are neural markers of individual differences in working memory (WM) capacity and whether these differences are only manifest when performing a demanding WM task or at all levels of difficulty. Each subject’s WM capacity was estimated using a modified digit span task prior to participation in an N-back task that varied difficulty from 1- to 4-back. While performing the N-back task, subjects wore scalp electrodes that allowed measurement of both event-related potentials (ERP) and event-related synchronization and desynchronization (ERS/ERD). Those subjects classified as low WM were more affected by the higher cognitive demands (many more errors in the 4-back task and generally slower responses) than those classified as high WM. These behavioral differences between the two groups were also apparent in the neural markers. Specifically, low WM subjects, when compared with high WM subjects, produced smaller P300 amplitudes and theta ERS, as well as greater alpha ERD at the most difficult level. Importantly, the observed differences in electrophysiological responses between the two groups were also observed at the lowest difficulty level, not just when the task challenged WM capacity. In addition, P300 amplitudes and alpha ERD responses were found to correlate with individual WM capacities independent of the task difficulty. These results suggest that there are qualitative neural differences among individuals with different WM capacities when approaching cognitive operations. Individuals with high WM capacities may make more efficient use of neural resources to keep their attention focused on the task-relevant information when performing cognitive tasks.
Oates, J. M., Reder, L. M., Cook, S. P., & Faunce, P. (2015). Spurious Recollection from a Dual-Process Framework. Cognitive Modeling in Perception and Memory: A Festschrift for Richard M. Shiffrin, 145-161.
Manelis, A., Reder, L. M. (2014) Effective connectivity among the working memory regions during preparation for and during performance of the n-back task. Frontiers in Human Neuroscience, 8:593. http://dx.doi.org/10.3389/fnhum.2014.00593
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    • Recent neuroimaging studies have shown that working memory (WM) task difficulty can be decoded from patterns of brain activation in the WM network during preparation to perform those tasks. The inter-regional connectivity among the WM regions during task preparation has not yet been investigated. We examined this question using the graph modeling methods IMaGES and LOFS, applied to the previously published fMRI data of Manelis and Reder (2013). In that study, subjects performed 1-, 2-, and 3-back tasks. Each block of n-back was preceded by a preparation period and followed by a rest period. The analyses of task-related brain activity identified a network of 18 regions that increased in activation from 1- to 3-back (Increase network) and a network of 17 regions that decreased in activation from 1- to 3-back (Decrease network). The graph analyses revealed two types of connectivity sub-networks within the Increase and Decrease networks: default and preparation-related. The default connectivity was present not only during task performance, but also during task preparation and during rest. We propose that this sub-network may serve as a core system that allows one to quickly activate cognitive, perceptual and motor systems in response to the relevant stimuli. The preparation-related connectivity was present during task preparation and task performance, but not at rest, and depended on the n-back condition. The role of this sub-network may be to pre-activate a connectivity road map in order to establish a top-down and bottom-up regulation of attention prior to performance on WM tasks.
Liu, X. L., Walsh, M. M., & Reder, L. M. (2014). An attentional-adaptation account of spatial negative priming: Evidence from event-related potentials. Cognitive, Affective, & Behavioral Neuroscience, 14(1), 49-61. http://dx.doi.org/10.3758/s13415-013-0237-8
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    • Negative priming (NP) refers to a slower response to a target stimulus if it has been previously ignored. To examine theoretical accounts of spatial NP, we recorded behavioral measures and event-related potentials (ERPs) in a target localization task. A target and distractor briefly appeared, and the participant pressed a key corresponding to the targets location. The probability of the distractor appearing in each of four locations varied, whereas the target appeared with equal probabilities in all locations. We found that response times (RTs) were fastest when the prime distractor appeared in its most probable (frequent) location and when the prime target appeared in the location that never contained a distractor. Moreover, NP effects varied as a function of location: They were smallest when targets followed distractors in the frequent distractor location finding not predicted by episodic-retrieval or suppression accounts of NP. The ERP results showed that the P2, an ERP component associated with attentional orientation, was smaller in prime displays when the distractor appeared in its frequent location. Moreover, no differences were apparent between negative-prime and control trials in the N2, which is associated with suppression processes, nor in the P3, which is associated with episodic retrieval processes. These results indicate that the spatial NP effect is caused by both short- and long-term adaptation in preferences based on the history of inspecting unsuccessful locations. This article is dedicated to the memory of Edward E. Smith, and we indicate how this study was inspired by his research career.
Nie, A., Griffin, M., Keinath, A., Walsh, M., Dittmann, A., & Reder, L. M. (2014). ERP profiles for face and word recognition are based on their status in semantic memory not their stimulus category. Brain Research, 1557 , 66-73. http://dx.doi.org/10.1016/j.brainres.2014.02.010
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    • Previous research has suggested that faces and words are processed and remembered differently as reflected by different ERP patterns for the two types of stimuli. Specifically, face stimuli produced greater late positive deflections for old items in anterior compared to posterior regions, while word stimuli produced greater late positive deflections in posterior compared to anterior regions. Given that words have existing representations in subjects' long-term memories (LTM) and that face stimuli used in prior experiments were of unknown individuals, we conducted an ERP study that crossed face and letter stimuli with the presence or absence of a prior (stable or existing) memory representation. During encoding, subjects judged whether stimuli were known (famous face or real word) or not known (unknown person or pseudo- word). A surprise recognition memory test required subjects to distinguish between stimuli that appeared during the encoding phase and stimuli that did not. ERP results were consistent with previous research when comparing unknown faces and words; however, the late ERP pattern for famous faces was more similar to that for words than for unknown faces. This suggests that the critical ERP difference is mediated by whether there is a prior representation in LTM, and not whether the stimulus involves letters or faces.
Liu, X. L., Liang, P., Li, K., & Reder, L. M. (2014). Uncovering the neural mechanisms underlying learning from tests. Plos One, 9(3): e92025. http://dx.doi.org/10.1371/journal.pone.0092025
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    • People learn better when re-study opportunities are replaced with tests. While researchers have begun to speculate on why testing is superior to study, few studies have directly examined the neural underpinnings of this effect. In this fMRI study, participants engaged in a study phase to learn arbitrary word pairs, followed by a cued recall test (recall second half of pair when cued with first word of pair), re-study of each pair, and finally another cycle of cued recall tests. Brain activation patterns during the first test (recall) of the studied pairs predicts performance on the second test. Importantly, while subsequent memory analyses of encoding trials also predict later accuracy, the brain regions involved in predicting later memory success are more extensive for activity during retrieval (testing) than during encoding (study). Those additional regions that predict subsequent memory based on their activation at test but not at encoding may be key to understanding the basis of the testing effect.
Manelis, A., & Reder, L. M. (2013). He Who Is Well Prepared Has Half Won The Battle: An fMRI Study of Task Preparation. Cerebral Cortex 2013 http://dx.doi.org/10.1093/cercor/bht262
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    • The neural mechanism underlying preparation for tasks that vary in difficulty has not been explored. This functional magnetic resonance imaging study manipulated task difficulty by varying the working memory (WM) load of the n-back task. Each n-back task block was preceded by a preparation period involving a screen that indicated the level of difficulty of the upcoming task. Consistent with previous work, activation in some brain regions depended on WM load in the task. These regions were used as regions of interest for the univariate and multivariate (classification) analyses of preparation periods. The findings were that the patterns of brain activation during task preparation contain information about the upcoming task difficulty. (1) A support vector machine classifier was able to decode the n-back task difficulty from the patterns of brain activation during task preparation. Those individuals whose activation patterns for anticipated 1- versus 2- versus 3-back conditions were classified with higher accuracy showed better behavioral performance on the task, suggesting that task performance depends on task preparation. (2) Left inferior frontal gyrus, intraparietal sulcus, and anterior cingulate cortex parametrically decreased activation as anticipated task difficulty increased. Taken together, these results suggest dynamic involvement of the WM network not only during WM task performance, but also during task preparation.
Griffin, M., Dewolf, M., Keinath, A., Liu, X. L., & Reder, L. M. (2013). Identical vs. Conceptual repetition FN400 and Parietal Old/New ERP components occur during encoding and predict subsequent memory. Brain Research 1512: 68-77. http://dx.doi.org/10.1016/j.brainres.2013.03.014
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    • This Event-Related Potential (ERP) study investigated whether components commonly measured at test, such as the FN400 and the parietal old/new components, could be observed during encoding and, if so, whether they would predict different levels of accuracy on a subsequent memory test. ERPs were recorded while subjects classified pictures of objects as man-made or natural. Some objects were only classified once while others were classified twice during encoding, sometimes with an identical picture, and other times with a different exemplar from the same category. A subsequent surprise recognition test required subjects to judge whether each probe word corresponded to a picture shown earlier, and if so whether there were two identical pictures that corresponded to the word probe, two different pictures, or just one picture. When the second presentation showed a duplicate of an earlier picture, the FN400 effect (a significantly less negative deflection on the second presentation) was observed regardless of subsequent memory response; however, when the second presentation showed a different exemplar of the same concept, the FN400 effect was only marginally significant. In contrast, the parietal old/new effect was robust for the second presentation of conceptual repetitions when the test probe was subsequently recognized, but not for identical repetitions. These findings suggest that ERP components that are typically observed during an episodic memory test can be observed during an incidental encoding task, and that they are predictive of the degree of subsequent memory performance.
Manelis. A., Paynter, C.A., Wheeler, M.E, & Reder, L.M. (2013). Repetition related changes in activation and functional connectivity in hippocampus predict subsequent memory. Hippocampus 23(1), 53-65. http://dx.doi.org/10.1002/hipo.22053
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    • Using fMRI, this study examined the relationship between repetition-related changes in the medial temporal lobe (MTL) activation during encoding and subsequent memory for similarity of repetitions. During scanning, subjects classified pictures of objects as natural or man-made. Each object-type was judged twice with presentations of either identical pictures or pictures of different exemplars of the same object. After scanning, a surprise recognition test required subjects to decide whether a probe word corresponded to pictures judged previously. When a subject judged the word as "old", a second judgment was made concerning the physical similarity of the two pictures. Repetition related changes in the MTL activation varied depending on whether or not subjects could correctly state that pictures were different. Moreover, psychophysiological interactions analyses showed that accuracy in recalling whether the two pictures were different was predicted by repetition-related changes in the functional connectivity of MTL with frontal regions. Specifically, correct recollection was predicted by increased connectivity between the left posterior hippocampus and the right inferior frontal gyrus, and also by decreased connectivity between the left posterior hippocampus and the left precentral gyrus on the second stimulus presentation. The opposite pattern was found for trials that were incorrectly judged on the nature of the repetition. These results suggest that successful encoding is predicted by a combination of increases and decreases in both the MTL activation and functional connectivity, and not merely by increases in activation and connectivity as suggested previously.
Liang, P., Manelis, A., Liu, X. L., Aizenstein, H. J., Gyulai, F., Quinlan, J. J., & Reder, L. M. (2012). Using arterial spin labeling perfusion MRI to explore how midazolam produces anterograde amnesia. Neuroscience Letters. 522 (7), 113-117. http://dx.doi.org/10.1016/j.neulet.2012.06.019
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    • While our previous work suggests that the midazolam-induced memory impairment results from the inhibition of new association formation, little is known about the neural correlates underlying these effects beyond the effects of GABA agonists on the brain. We used arterial spin-labeling perfusion MRI to measure cerebral blood flow changes associated with the effects of midazolam on ability to learn arbitrary word-pairs. Using a double-blind, within- subject cross-over design, subjects studied word-pairs for a later cued-recall test while they were scanned. Lists of different word-pairs were studied both before and after an injection of either saline or midazolam. As expected, recall was severely impaired under midazolam. The contrast of MRI signal before and after midazolam administration revealed a decrease in CBF in the left dorsolateral prefrontal cortex (DLPFC), left cingulate gyrus and left posterior cingulate gyrus/precuneus. These effects were observed even after controlling for any effect of injection. A strong correlation between the midazolam-induced changes in neural activity and memory performance was found in the left DLPFC. These findings provide converging evidence that this region plays a critical role in the formation of new associations and that low functioning of this region is associated with anterograde amnesia.
Manelis, A., Reder, L.M. (2012). Procedural Learning and Associative Memory Mechanisms Contribute to Contextual Cueing: Evidence from fMRI and Eye-Tracking. Learning & Memory. 19(10) 527-534. http://dx.doi.org/10.1101/lm.025973.112
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    • Using a combination of eye-tracking and fMRI in a contextual cueing task, we explored the mechanisms underlying the facilitation of visual search for repeated spatial configurations. When configurations of distractors were repeated, greater activation in right hippocampus corresponded to greater reductions in the number of saccades to locate the target. A psychophysiological interactions analysis for repeated configurations revealed that a strong functional connectivity between this area in the right hippocampus and the left superior parietal lobule early in learning was significantly reduced towards the end of the task. Practice related changes (which we call procedural learning) in activation in temporo-occipital and parietal brain regions depended on whether or not spatial context was repeated. We conclude that context repetition facilitates visual search through chunk formation that reduces the number of effective distractors that have to be processed during search. Context repetition influences procedural learning in a way that allows for continuous and effective chunk updating.
Reder, L. M., Victoria, L. W., Manelis, A., Oates, J. M., Dutcher, J. M., Bates, J. T., Cook, S., Aizenstein, H. A., Quinlan, J., Gyulai, F. (2012). Why it's easier to remember seeing a face we already know than one we don't: pre-existing memory representations facilitate memory formation. Psychological Science 24(3):363-72. http://dx.doi.org/10.1177/0956797612457396
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    • In two experiments, we provide support for the hypothesis that stimuli with pre-existing memory representations (e.g., famous faces) are easier to associate to their encoding context than are stimuli that lack a long-term memory representation (e.g., unknown faces). Subjects viewed faces superimposed on different backgrounds (e.g., Eiffel Tower). Face recognition on a surprise memory test was better when the encoding background was reinstated; however, the reinstatement advantage was modulated by how many faces had been seen with a given background, and reinstatement did not improve recognition for unknown faces. The follow-up experiment added a drug intervention that inhibits the ability to form new associations. In the drug condition, context reinstatement did not improve recognition for famous or unknown faces. The results suggest that it is easier to associate context to faces that have a pre-existing long-term memory representation.
Manelis, A., Reder, L. M., Hanson, S. J. (2011). Dynamic changes in the medial temporal lobe during incidental learning of object-location associations. Cerebral Cortex. 22(4), 828-837. http://dx.doi.org/10.1093/cercor/bhr151
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    • The role of the medial temporal lobe (MTL) in associative memory encoding has been the focus of many memory experiments. However, there has been surprisingly little investigation of whether the contributions of different MTL subregions (amygdala, hippocampus (HPC), parahippocampal (PHc), perirhinal (PRc) and temporal polar (TPc) cortices) shift across multiple presentations during associative encoding. We examined this issue using event-related fMRI and a multi-voxel pattern classification analysis. Subjects performed a visual search task, becoming faster with practice to locate objects whose locations were held constant across trials. The classification analysis implicated right HPC and amygdala early in the task when the speed up from trial to trial was greatest. The same analysis implicated right PRc and TPc late in learning when speed-up was minimal. These results suggest that associative encoding relies on complex patterns of neural activity in MTL that cannot be expressed by simple increases or decreases of BOLD signal during learning. Involvement of MTL subregions during encoding of object- location associations depends on the nature of the learning phase. Right HPC and amygdala support active integration of object and location information, while right PRc and TPc are involved when object and spatial representations become unitized into a single representation.
Manelis, A., Wheeler, M.E., Paynter, C. A., Storey, L & Reder, L. M. (2011). Opposing patterns of neural priming in same-exemplar vs. different-exemplar repetition predict subsequent memory. NeuroImage. 55(2):763-72. http://dx.doi.org/10.1016/j.neuroimage.2010.12.034
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    • The present neuroimaging study examines how repetition-related neural attenuation effects differ as a function of the perceptual similarity of the repetition and subsequent memory. One previous study (Turk-Browne et al., 2006) reported greater attenuation effects for subsequent hits than for misses. Another study (Wagner et al., 2000) found that neural attenuation is negatively correlated with subsequent memory. These opposing results suggest that repetition-related neural attenuation for subsequent hits and misses may be driven by different factors. In order to investigate the factors that affect the degree of neural attenuation, we varied perceptual similarity between repetitions in a scanned encoding phase that was followed by a subsequent memory test outside the scanner. We demonstrated that the degree of neural attenuation in the object processing regions depends on the interaction between perceptual similarity across repeated presentations and the quality their encodings. Specifically, the same areas that decreased neural signal for repetitions of same exemplars that were subsequently recognized with confidence that the repetitions were identical showed a decrease in neural signal for different-exemplar misses but not for the corresponding subsequently recognized hits. Our results imply that repetition-related neural attenuation should be related to the more efficient processing of perceptual properties of the stimuli only if subjects are able to subsequently remember the stimuli. Otherwise, the cause of attenuation may be in the failure to encode the stimuli on the second presentation as shown by the pattern of neural attenuation for the different-exemplar misses.

Oates, J.M. & Reder L.M. (2010). Memory for pictures: Sometimes a picture is not worth a single word. In Benjamin, A.S. (Ed.), Successful Remembering and Successful Forgetting: A Festschrift in Honor of Robert A. Bjork. New York: Psychological Press, p.447-462.

Buchler, N. G., Faunce, P. A., Light, L. L., Gottfredson, N., & Reder, L. M. (2010). Effects of repetition on associative recognition in young and older Adults: Item and associative strengthening. Psychology and Aging. 22(1), 104-121. http://dx.doi.org/10.1037/a0020816
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    • Young and older adults studied word pairs and later discriminated studied pairs from various types of foils including recombined word-pairs and foil pairs containing one or two previously unstudied words. We manipulated how many times a specific word pair was repeated (1 or 5) and how many different words were associated with a given word (1 or 5) to tease apart the effects of item familiarity from recollection of the association. Rather than making simple old/new judgments, subjects chose one of five responses: (a) Old-Old (original), (b) Old-Old (rearranged), (c) Old-New, (d) New-Old, (e) New-New. Veridical recollection was impaired in old age in all memory conditions. There was evidence for a higher rate of false recollection of rearranged pairs following exact repetition of study pairs in older but not younger adults. In contrast, older adults were not more susceptible to interference than young adults when one or both words of the pair had multiple competing associates. Older adults were just as able as young adults to use item familiarity to recognize which word of a foil was old. This pattern suggests that recollection problems in advanced age are because of a deficit in older adults? formation or retrieval of new associations in memory. A modeling simulation provided good fits to these data and offers a mechanistic explanation based on an age-related reduction of working memory.

Paynter, C.A., Kotovsky, K., & Reder, L.M. (2010). Problem-solving without awareness: An ERP investigation. Neuropsychologia, 48(10), 3137-3144. http://dx.doi.org/10.1016/j.neuropsychologia.2010.06.029
  • Show abstract
    • When subjects are given the balls-and-boxes problem-solving task (Kotovsky & Simon, 1990), they move rapidly towards the goal after an extended exploratory phase, despite having no awareness of how to solve the task. We investigated possible non-conscious learning mechanisms by giving subjects three runs of the task while recording ERPs. Subjects showed significant differences in their ERP components during the exploratory phase between correct and incorrect moves. Exploratory incorrect moves were associated with a shallower response-locked N1 component and a larger response-locked P3 component compared with exploratory correct moves. Subjects who solved the task more quickly exhibited a trend towards larger N1 and P3 components. These results suggest that the brain processes information about the correctness of a move well before subjects are aware of move correctness. They further suggest that relatively simple attentional and error-monitoring processes play an important role in complex problem-solving.

Victoria, L.W. & Reder, L.M. (2010). How midazolam can help us understand human memory: Three illustrations. Frensch, P. (Ed.), Cognitive and Neuropsychological Issues. Volume 1, Psychology Press, p.225-238.

Paynter, C.A., Reder, L.M., & Kieffaber, P.D. (2009). Knowing we know before we know: ERP correlates of initial feeling-of-knowing. Neuropsychologia, 47(3), 796-803. http://dx.doi.org/10.1016/j.neuropsychologia.2008.12.009
  • Show abstract
    • Subjects performed a rapid feeling-of-knowing task developed by Reder and Ritter (1992), while event-related potentials (ERPs) were recorded to identify the time course of feeling-of-knowing signals. Subjects were shown a series of math problems, some of which were repeated multiple times during the course of the experiment, and subjects had to rapidly decide whether the answer to a given problem could be quickly retrieved from memory (retrieval trials) or had to be calculated on scrap paper (calculate trials). Behavioral results replicated the 1992 study, showing that subjects can estimate whether the answer is known much faster than the answer can be retrieved. ERPs time-locked to the onset of the math problem showed that accurate retrieval trials were associated with greater positivity for an early frontal P2 component (epoched from 180-280 ms) and a frontal-central P3 component (epoched from 300-550 ms). Moreover, this feeling-of- knowing signal was not found for subjects who never obtained a successful on-time retrieval. We interpret these findings as suggesting that initial feeling-of-knowing relies on a rapid assessment of the perceptual fluency with which the stimulus is processed. If a stimulus is deemed sufficiently familiar, the activation level of an internal problem representation is used to arrive at a decision of whether to search for the answer or to calculate it.

Reder, L.M., Park, H., & Kieffaber, P.D. (2009). Memory systems do not divide on consciousness: Reinterpreting memory in terms of activation and binding. Psychological Bulletin, 135(1), 23-49. http://dx.doi.org/10.1037/a0013974
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    • There is a popular hypothesis that performance on implicit and explicit memory tasks reflects two distinct memory systems. Explicit memory is said to store those experiences that can be consciously recollected and implicit memory is said to store experiences and affect subsequent behavior but is unavailable to conscious awareness. Although this division based on awareness is a useful taxonomy for memory tasks, we review the evidence that the unconscious character of implicit memories does not necessitate that it be treated as a separate system of human memory. We also argue that some implicit and explicit memory tasks share the same memory representations and that the important distinction is whether the task (implicit or explicit) requires the formation of a new association. Dissociations from the behavioral, amnesia, and neuroimaging literatures that have been advanced in support of separate explicit and implicit memory systems are reviewed and critiqued by highlighting contradictory evidence and by illustrating how the data can be accounted for using a simple computational memory model that assumes the same memory representation for those disparate tasks.

Buchler, N.E.G, Light, L.L., & Reder, L.M. (2008). Memory for items and associations: Distinct representations and processes in associative recognition. Journal of Memory and Language, 59, 183-199. http://dx.doi.org/10.1016/j.jml.2008.04.001
  • Show abstract
    • In two experiments, participants studied word pairs and later discriminated old (intact) word pairs from foils, including recombined word pairs and pairs including one or two previously unstudied words. Rather than making old/new memory judgments, they chose one of five responses: (1) Old-Old (original), (2) Old-Old (rearranged), (3) Old-New, (4) New-Old, (5) New-New. To tease apart the effects of item familiarity from those of associative strength, we varied both how many times a specific word-pair was repeated (1 or 5) and how many different word pairs were associated with a given word (1 or 5). Participants could discriminate associative information from item information such that they recognized which word of a foil was new, or whether both were new, as well as discriminating recombined studied words from original pairings. The error and latency data support the view that item and associative information are stored as distinct memory representations and make separate contributions at retrieval.

Reder, L.M., Paynter, C., Diana, R.A., Ngiam, J., & Dickison, D. (2007). Experience is a double-edged sword: A computational model of the encoding/retrieval tradeoff with familiarity. In Ross, B. & Benjamin, A.S. (Eds.), The Psychology of Learning and Motivation, Academic Press, 271-312.

Reder, L.M., Oates, J.M., Dickison, D., Anderson, J.R., Gyulai, F., Quinlan, J.J., Ferris, J.L., Dulik, M. & Jefferson, B. (2007). Retrograde facilitation under midazolam: The role of general and specific interference. Psychonomic Bulletin & Review, 14(2), 261-269.
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    • In a double-blind, placebo-controlled experiment that used midazolam, a benzodiazepine that creates temporary amnesia, we compared acquisition and retention of paired associates of different types. Some word pairs were studied before the injection of saline or midazolam, and two lists of word pairs were studied after the injection. Critical comparisons involved retention of pairs that were practiced on all three lists, pairs studied on only one list, and pairs that involved recombining cue and response terms from one list to the next, as a function of drug condition. Previous research with benzodiazepines had found retrograde facilitation for material acquired prior to injection, compared with the control condition. One explanation for this facilitation is that the anterograde amnesia produced by the benzodiazepine frees up the hippocampus to better consolidate previously learned material (Wixted, 2004, 2005). We accounted for a rich data set using a simple computational model that incorporated interference effects (cue overload) at retrieval for both general (experimental context) interference and specific (stimulus term) interference without the need to postulate a role for consolidation. The computational model as an Excel spreadsheet may be downloaded from www.psychonomic.org/archive.

Buchler, N.E.G., & Reder, L.M. (2007). Modeling age-related memory deficits: A two-parameter solution. Psychology & Aging, 22(1), 104-121. http://dx.doi.org/10.1037/0882-7974.22.1.104
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    • Recent research and meta-analytic reviews suggest that 1 observed pattern of impaired and intact memory performance with advancing age is a deficit in measures of episodic but not semantic memory. The authors used computational modeling to explore a number of age-related parameters to account for this pattern. A 2-parameter solution based on lifelong experience successfully fit the pattern of results in 5 published studies of the word-frequency mirror effect and paired-associate recognition. Lifelong experience increases the strength (resting level of activation) of concepts in the network but also saturates the network with an increasing number of episodic associations to each concept. More episodic associations to each concept mean that activation spreads more diffusely, making retrieval of any newly established memory trace less likely; however, the greater strength of a concept makes recognition based on familiarity more likely. The simulations provide good quantitative fits to the extant age-related memory literature and support the plausibility of this mechanistic account.

Reder, L.M., Proctor, I., Anderson, J.R., Gyulai, F., Quinlan, J.J., & Oates, J.M. (2006). Midazolam does not inhibit association formation, just its storage and strengthening. Psychopharmacology, 188(4), 462-471. http://dx.doi.org/10.1007/s00213-006-0436-x
  • Show abstract
    • Rationale Although there have been many studies examining the effects of benzodiazepines on memory performance, their effects on working memory are equivocal and little is known about whether they affect the efficacy of practice of already learned material.
      Objectives The objectives in two experiments were to examine (a) whether midazolam impairs performance on a working memory task designed to minimize mnemonic strategies such as rehearsal or chunking of information to be recalled and (b) the effect of midazolam on repeated practice of paired associates that were learned before drug administration.
      Materials and methods Both experiments involved subcutaneous administration of 0.03 mg/kg of body weight of saline or midazolam in within-subject, placebo-controlled designs, involving 23 subjects in (a) and 31 in (b).
      Results The drug had no effect on the ability to recall the digits in serial order even though the encoding task prevented the digits from being rehearsed or maintained in an articulatory buffer. Paired associates that were learned before the injection showed a benefit of subsequent practice under saline but not under midazolam.
      Conclusions The results suggest that (a) midazolam does not affect the formation of new associations in short-term memory (STM) provided that the presentation rate is not too fast to form these associations when sedated, despite the evidence that the drug blocks long-term memory (LTM) retention of associations; and (b) the potential for overlearning with practice of learned associations in LTM is adversely affected by midazolam such that repeated exposures do not strengthen new learning.

Park, H., Arndt, J.D., & Reder, L.M. (2006). A contextual interference account of distinctiveness effects in recognition. Memory & Cognition, 34(4), 743-751.
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    • In this article, we report on two experiments that aimed to shed light on the memorability effect that derives from varying the uniqueness of contextual cues presented at encoding and retrieval. We sought to understand the locus of the recognition advantage for studying and testing words with nominally irrelevant features that are rarely shared with other words ('low-fan' features) as compared with features that are studied with more words ('high-fan' features). Each word was studied with one high-fan feature and one low-fan feature, but only one of the two features was reinstated at test. Recognition judgments were more accurate when the low-fan feature was reinstated than when the high-fan feature was reinstated. The data suggest that encoding cues that suffer from contextual interference negatively affect retrieval and do so by hindering recollection-based processing.

Diana, R.A. & Reder, L.M. (2006). The low frequency encoding disadvantage: Word frequency affects processing demands. Journal of Experimental Psychology: Learning, Memory, & Cognition, 32(4), 805-815. http://dx.doi.org/10.1037/0278-7393.32.4.805
  • Show abstract
    • Low-frequency words produce more hits and fewer false alarms than high-frequency words in a recognition task. The low-frequency hit rate advantage has sometimes been attributed to processes that operate during the recognition test (e.g., L. M. Reder et al., 2000). When tasks other than recognition, such as recall, cued recall, or associative recognition, are used, the effects seem to contradict a low-frequency advantage in memory. Four experiments are presented to support the claim that in addition to the advantage of low-frequency words at retrieval, there is a low-frequency disadvantage during encoding. That is, low-frequency words require more processing resources to be encoded episodically than high-frequency words. Under encoding conditions in which processing resources are limited, low-frequency words show a larger decrement in recognition than high-frequency words. Also, studying items (pictures and words of varying frequencies) along with low-frequency words reduces performance for those stimuli.

Reder, L.M., Oates, J.M., Thornton, E.R., Quinlan, J.J., Kaufer, A., & Sauer, J. (2006). Drug induced amnesia hurts recognition, but only for memories that can be unitized. Psychological Science, 17(7), 562-567.
  • Show abstract
    • Midazolam is a drug that creates temporary anterograde amnesia. In a within-subjects, double-blind experiment, participants studied a list of stimuli after receiving an injection of midazolam in one session and after receiving saline in another session. The lists consisted of three types of stimuli: words, photographs, and abstract pictures. Recognition memory was tested at the end of each session. Memory was reliably poorer in the midazolam condition than the saline condition, but this amnesic effect was significantly smaller for pictorial stimuli than for words and almost nonexistent for abstract pictures. We argue that the less familiar the stimulus, the less likely it is to be associated with an experimental context. These data bolster our claim that unitization increases the chances of episodic binding and that drug-induced amnesia prevents episodic binding regardless of unitization.

Diana, R., Reder, L.M., Arndt. J., & Park, H. (2006). Models of recognition: A review of arguments in favor of a dual process account. Psychonomic Bulletin & Review, 13, 1-21. [Lead Article]
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    • The majority of computationally specified models of recognition memory have been based on a single-process interpretation, claiming that familiarity is the only influence on recognition. There is increasing evidence that recognition is, in fact, based on two processes: recollection and familiarity. This article reviews the current state of the evidence for dual-process models, including the usefulness of the remember/know paradigm, and interprets the relevant results in terms of the source of activation confusion (SAC) model of memory. We argue that the evidence from each of the areas we discuss, when combined, presents a strong case that inclusion of a recollection process is necessary. Given this conclusion, we also argue that the dual-process claim that the recollection process is always available is, in fact, more parsimonious than the single-process claim that the recollection process is used only in certain paradigms. The value of a well-specified process model such as the SAC model is discussed with regard to other types of dual-process models.

Diana, R., & Reder, L.M. (2005). The list strength effect: A contextual competition account. Memory & Cognition, 33(7), 1289-1302.
  • Show abstract
    • Research on the list strength effect (LSE) has shown that learning some words on a list more strongly than others impairs memory for the weakly learned words when tested with a recall task. Norman (2002) demonstrated that the LSE also occurs within the recollection process of a recognition test. In this study, a mechanistic dual-process account of the LSE was tested that simultaneously makes predictions concerning additional sources of context in interference effects. In two experiments, we attempted to replicate Norman's (2002) findings and provide the basis for our modeling efforts. We found evidence for a recollection LSE in raw measures of responding, with memory performance also benefiting from reinstatement of perceptual characteristics at test. However, large differences in the hits between the lists were accompanied by small differences in false alarms, such that when d' is calculated, differences between the lists are not significant. We propose an account of the LSE whereby the actual effect of competition between items on the list is small, although present, and difficult to distinguish from large effects of bias due to the strength manipulations. We argue that our findings provide support for a mechanistic explanation of LSE that is based on competition of source activation and changes in the thresholds for responses.

Diana, R., Vilberg, K.L., & Reder, L.M. (2005). Identifying the ERP correlate of a recognition memory search attempt, Cognitive Brain Research, 24, 674-684. http://dx.doi.org/10.1016/j.cogbrainres.2005.04.001
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    • Previous recognition memory studies have looked for differences in brain activity during recollection-and familiarity-based responding. Although an ERP component correlated with recollection success has been reported, no analogous component related to search initiation has been found. We argue that such a component has not been discovered because studies have compared trials in which participants have made a search attempt and failed (such as Know responses) with those in which the search attempt is successful (such as Remember responses). In the current study, we compared a task that required judgments of lifetime familiarity (differentiating famous from nonfamous names) with one that required judgments of episodic information (deciding whether a name was seen previously in the experiment). By comparing a task on which familiarity judgments were made with no search attempt to a second task in which a search attempt was likely to occur, we identified a component that may reflect the initiation of a memory search. This effect, maximal between 190 and 235 ms, is correlated with Old judgments in the episodic task. Previous ERP findings (e.g., FN400, parietal old/new effect) were also replicated in the present study.

Park, H., Reder, L.M., & Dickison, D. (2005). The effects of word frequency and similarity on recognition judgments: The role of recollection. Journal of Experimental Psychology: Learning, Memory & Cognition, 31(3), 568-578. http://dx.doi.org/10.1037/0278-7393.31.3.568
  • Show abstract
    • K. J. Malmberg, J. Holden, and R. M. Shiffrin (2004) reported more false alarms for low- than high-frequency words when the foils were similar to the targets. According to the source of activation confusion (SAC) model of memory, that pattern is based on recollection of an underspecified episodic trace rather than the error-prone familiarity process. The authors tested the SAC account by varying whether participants were warned about the nature of similar foils and whether the recognition test required the discrimination. More false alarms for low-frequency similar items occurred only when participants were not warned at study about the subtle features to be discriminated later. The differential false-alarm rate by word frequency corresponded to the pattern of remember responses obtained when the test instructions did not ask for a subtle discrimination, supporting the SAC account that reversed false-alarm rates to similar foils are based on the recollection process.

Diana, R. & Reder, L.M. (2004). Visual vs. verbal metacognition: Are they really different? In D.T. Levin (Ed), Thinking and Seeing: Visual Metacognition in Adults and Children. Westport, CT: Greenwood/Praeger, 187-201.

Park H., Quinlan, J.J., Thornton, E.R., & Reder, L.M. (2004). The effect of midazolam on visual search: Implications for understanding amnesia. Proceedings of the National Academy of Sciences, 101(51), 17879-17883.
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    • The notion of multiple memory systems based on conscious accessibility has been supported largely by neuropsychological patient studies. Specifically, it was widely held that amnesic patients have impaired explicit memory performance but spared implicit memory performance. However, recent patient studies have called the implicit_explicit memory distinction into question. In this study, normal participants were tested on a visual search task, once after an injection of midazolam, an anesthetic that induces temporary amnesia, and once after an injection of saline. Under the influence of midazolam, participants did not show facilitation in search times for repeated configurations (contextual cuing), although there was a general speed-up in performance across blocks in both the midazolam and saline conditions. Neither the contextual-cuing effect nor the procedural-learning effect was available to subjective experience, yet only one of these was affected by midazolam-induced amnesia. These data call into question the notion that memory systems divide on the basis of subjective experience of consciousness or reportability. Rather, the findings support the contention that anterograde amnesia affects learning that depends on building novel associations in memory and that this deficit does not hinge upon accessibility to consciousness.

Park, H. & Reder, L.M. (2004). Moses illusion: Implication for human cognition. In Pohl, R.F. (Ed). Cognitive Illusions. Hove: Psychology Press, 275-291.

Sohn, M.-H., Anderson, J.R., Reder, L.M. & Goode, A. (2004). Differential fan effect and attentional focus. Psychonomic Bulletin and Review, 11(4), 729-734.
  • Show abstract
    • As people study more facts about a concept, it takes longer to retrieve a particular fact about that concept. This fan effect (Anderson, 1974) has been attributed to competition among associations to a concept. Alternatively, the mental-model theory (Radvansky & Zacks, 1991) suggests that the fan effect disappears when the related concepts are organized into a single mental model. In the present study, attentional focus was manipulated to affect the mental model to be constructed. One group of participants focused on the person dimension of person-location pairs, whereas the other group focused on the location dimension. The result showed that the fan effect with the focused dimension was greater than the fan effect with the nonfocused dimension, which is contrary to the mental-model theory. The number of associations with a concept is indeed crucial during retrieval, and the importance of the information seems to be accentuated with attentional focus.

Diana, R., Peterson, M.J., & Reder, L.M. (2004). The role of spurious feature familiarity in recognition memory. Psychonomic Bulletin & Review, 11(1), 150-156.
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    • In two experiments, we investigated the role of perceptual information in spurious recognition judgments. Participants viewed lists of words in various unusual fonts. The frequency with which each font was presented was manipulated at study: Each font was presented with 1 or 12 different words in Experiment 1 and with 1 or 20 words in Experiment 2. Although the participants were instructed in a word recognition test to judge only the basis of the word, regardless of font, there were significantly more false alarms for new words not seen in a previously prevented font than for new words presented in a novel (not seen at study) font in Experiment 1. In Experiment 2, the participants were significantly more likely to make a false alarm to a new word seen in a font that had been used to present 20 words during study than to a font that had been used to present only 1 word during study. The data show a mirror effect, in which words tested in low-frequency fonts produced more hits and fewer false alarms than did words tested in high-frequency fonts. These results show that irrelevant perceptual information plays a role recognition judgments by providing spurious sources of familiarity and, thus, provide evidence that perceptual information is represented and processed in the same way as semantic information.

Rehling, J., Lovett, M., Lebiere, C., Reder, L., & Demiral, B. (2004) Modeling complex tasks: An individual difference approach. In Proceedings of the 26th Annual Conference of the Cognitive Science Society (1137-1142). August 4-7, Chicago, USA.
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    • It is the usual case in cognitive modeling that a model's output is compared to the average of a number of subjects, in which case the enterprise of modeling is apparently to capture the behavior of the typical individual. Our approach is to administer two simple tasks to each subject, using performance on those tasks as measures of individual ability. Those measures are then used as the values for parameters in an ACT-R model of a more complex task, so that the model can predict individual performance on that task.

Cary, M. & Reder, L.M. (2003). A dual-process account of the list-length and strength-based mirror effects in recognition. Journal of Memory and Language, 49(2), 231-248. http://dx.doi.org/10.1016/S0749-596X(03)00061-5
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    • Manipulating either list length (e.g., few vs. many study items) or encoding strength (e.g., one presentation vs. multiple presentations of each study item) produces a recognition mirror effect. A formal dual-process theory of recognition memory that accounts for the word-frequency mirror effect is extended to account for the list-length and strength-based mirror effects. According to this theory, the hit portions of these mirror effects result from differential ease of recollection-based recognition, and the false alarm portions result from differential reliance on familiarity-based recognition. This account yields predictions for participants_ Remember and Know responses as a function of list length and encoding strength. Empirical data and model fits from four experiments support these predictions. The data also demonstrate a reliable list-length effect when several potential confounding factors are controlled, contributing to the debate regarding the effect of list length on recognition.

Reder, L.M., Weber, K., Shang, Y., & Vanyukov, P. (2003). The adaptive character of the attentional system: Statistical sensitivity in a target localization task. Journal of Experimental Psychology: Human Perception and Performance, 29(3), 631-649. http://dx.doi.org/10.1037/0096-1523.29.3.631
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    • A localization task required participants to indicate which of 4 locations contained a briefly displayed target. Most displays also contained a distractor that was not equally probable in these locations, affecting performance dramatically. Responses were faster when a display had no distractor and almost as fast when the distractor was in its frequent location. Conversely, responses were slower when targets appeared in frequent-distractor locations, even though targets were equally likely in each location. Negative-priming effects were reliably smaller when targets followed distractors in the frequentdistractor location compared to the rare-distractor location, challenging the episodic-retrieval account. Experiment 2 added a 5th location that rarely displayed distractors and never targets, yet responses slowed most when distractors appeared there. The results confirmed that the attentional system is sensitive to first- and higher-order statistical patterns and can make short- and long-term adjustments in preferences based on prior history of inspecting unsuccessful locations.

Arndt, J. & Reder, L.M. (2003). The effect of distinctive visual information on false recognition. Journal of Memory and Language, 48, 1-15. [Lead Article]
  • Show abstract
    • Using the false memory paradigm (Deese, 1959), recently revived by Roediger and McDermott (1995), we examined the effect on true and false recognition of presenting study items in unusual looking fonts. In one condition, each font was associated with a single study item. In a second condition, each font was presented 12 times per study list, randomly distributed across several themes. In a third condition, each font was presented 12 times in the study list, and was associated with a particular study theme. False recognition levels were lowest when there was a unique association between each font and a single study item, whereas false recognition levels were highest when all items from a theme were presented in the same font. Further, the effects of font condition on false recognition of lures maintained when font condition was manipulated within participants and lists. These results, taken together, are inconsistent with theories proposing that false recognition reduction is the product of global shifts in response strategies across conditions (e.g., Schacter, Israel, & Racine, 1999). However, perspectives highlighting the effects of memory based processes on true and false recognition provide an adequate account.

Rehling, J., Demiral, B., Lebiere, C., Lovett, M., & Reder, L. (2003). Modeling individual difference factors in a complex task environment. In F. Detje, D. Doerner, & H. Schaub (Eds.), In Proceedings of the Fifth International Conference on Cognitive Modeling (287-288). Bamberg, Germany: Universitats-Verlag Bamberg.
  • Show abstract
    • Cognitive models are often used to predict the average performance of a population. For many purposes, however, generating predictions of individual performance is crucial. We propose a methodology in which the ACT-R architecture is extended, through the setting of architectural parameters that represent individual differences, into a model of individual behavior. This approach can provide a vast range of predictive and diagnostic capabilities from a modest initial investment of resources.

Cary, M. & Reder, L.M. (2002). Metacognition in strategy selection: Giving consciousness too much credit. In P. Chambres, M. Izaute, & P.J. Marescaux (Eds.), Metacognition: Process, Function, and Use. New York, NY: Kluwer, 63-78.
  • Show abstract
    • Many researchers believe that metacognitive processes regulate strategy selection. Another common assumption is that metacognitive processes, such as strategy selection, entail conscious processing or decision making. In this chapter, we examine whether conscious awareness is a critical aspect of strategy selection. We review evidence that first establishes that strategy selection varies both across and within individuals in response to dynamic features of the environment. Then, we present evidence that strategy adaptation can occur without (a) conscious consideration of different strategies or (b) conscious awareness of factors influencing one's strategy use. Specifically, shifts in strategy use occurred when people seemed to be unaware (a) that there were shifts in their strategy use or (b) that there were changes in the characteristics of the environment that, nonetheless, affected their strategy use.

Arndt, J. & Reder, L.M. (2002). Word frequency and receiver-operating characteristic curves in recognition memory: Evidence for a dual-process interpretation. Journal of Experimental Psychology: Learning, Memory, and Cognition, 28, 830-842. http://dx.doi.org/10.1037//0278-7393.28.5.830
  • Show abstract
    • Recently, theorists have suggested that the word frequency mirror effect in recognition memory can be understood in terms of a dual-process model (Joordens & Hockley, 2000; Reder, Nhouyvanisvong, Schunn, Ayers, Angstadt, & Hikari, 2000). These explanations propose that low frequency words are recollected more often than high frequency words, producing the hit rate differences in the word frequency effect, while high frequency words are more familiar, producing the false alarm differences. In the present pair of experiments, we demonstrate that the analysis of receiver-operating characteristic (ROC) curves provides critical information in support of this interpretation. Specifically, when participants were required to discriminate between studied nouns and their plurality reversed complements (e.g., Hintzman & Curran, 1994), the ROC curve relating hits and false alarms was accurately described by a threshold model, which is consistent with recollection based recognition. Further, the ROC curves resulting from plurality discrimination showed characteristics consistent with the interpretation that participants recollected low frequency items more than high frequency items, providing support for the dual-process explanation of the word frequency mirror effect.

Reder, L.M., Angstadt, P., Cary, M., Erickson, M.A., & Ayers, M.A. (2002). A reexamination of stimulus-frequency effects in recognition: two mirrors for low- and high-frequency pseudowords. Journal of Experimental Psychology: Learning, Memory & Cognition, 28, 138-152. http://dx.doi.org/10.1037//0278-7393.28.1.138
  • Show abstract
    • The word-frequency mirror effect (more hits and fewer false alarms for low-frequency than for high-frequency words) has intrigued memory researchers, and multiple accounts have been offered to explain the result. In this study, participants were differentially familiarized to various pseudowords in a familiarization phase that spanned multiple weeks. Recognition tests given during the first week of familiarization replicated a result of W. T. Maddox and W. K. Estes (1997) that failed to show the classic word-frequency mirror effect for pseudowords; however, recognition tests given toward the end of training showed the classic mirror pattern. In addition, a stimulus-frequency mirror effect for remember vs. know judgments was obtained. These data are consistent with an account of the mirror effect that posits the involvement of dual processes for episodic recognition.

Reder, L.M., Donavos, D.K., & Erickson, M.A. (2002). Perceptual match effects in direct tests of memory: The role of contextual fan. Memory & Cognition, 30(2), 312-323.
  • Show abstract
    • The aim of the present study was to determine whether physical attributes of a memory representation would affect explicit memory performance and, if so, what type of factors would affect the size of a perceptual match effect. Subjects studied words in different, uncommon fonts and were later asked whether the word had been studied earlier. Words could be re-presented in the original font, a font studied with another word, or a font not seen earlier. In two additional experiments, we varied the numbers of words studied in the same unusual font (1 vs. 12 words per font). Recognition memory for the words was better if the test and study fonts matched, and this effect was larger for fonts not shared with other words. Moreover, old judgments were most likely to be classified as remember responses when words were re-presented in the same font when it had not been studied with other words. Although we found a significant effect of levels of processing, this factor did not interact with whether the font matched between study and test. These results are consistent with the predictions of the source of activation confusion model of memory and suggest that perceptual information operates according to the same memory principles as conceptual information.

Anderson, J.R., Budiu, R., & Reder, L.M. (2001). A theory of sentence memory as part of a general theory of memory. Journal of Memory and Language, 45, 337-367 [lead article]. http://dx.doi.org/10.1006/jmla.2000.2770
  • Show abstract
    • We describe an ACT-R model for sentence memory that extracts both a parsed surface representation and a propositional representation. In addition, if possible for each sentence, pointers are added to a long-term memory referent which reflects past experience with the situation described in the sentence. This system accounts for basic results in sentence memory without assuming different retention functions for surface, propositional, or situational information. There is better retention for gist than for surface information because of the greater complexity of the surface representation and because of the greater practice of the referent for the sentence. This model's only inference during sentence comprehension is to insert a pointer to an existing referent. Nonetheless, by this means it is capable of modeling many effects attributed to inferential processing. The ACT-R architecture also provides a mechanism for mixing the various memory strategies that participants bring to bear in these experiments.

Daily, L.Z., Lovett, M.C., & Reder, L.M. (2001). Modeling individual differences in working memory performance: A source activation account. Cognitive Science, 25, 315-353 [lead article].
  • Show abstract
    • Working memory resources are needed for processing and maintenance of information during cognitive tasks. Many models have been developed to capture the effects of limited working memory resources on performance. However, most of these models do not account for the finding that different individuals show different sensitivities to working memory demands, and none of the models predicts individual subjects' patterns of performance. We propose a computational model that accounts for differences in working memory capacity in terms of a quantity called source activation, which is used to maintain goal-relevant information in an available state. We apply this model to capture the working memory effects of individual subjects at a fine level of detail across two experiments. This, we argue, strengthens the interpretation of source activation as working memory capacity.

Schunn, C.D., Lovett, M.C., & Reder, L.M. (2001). Awareness and working memory in strategy adaptivity. Memory & Cognition, 29(2), 254-266.
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    • To further the understanding of the mechanisms of strategy choice, in three experiments, we investigate the role of explicit awareness and working memory in strategy adaptivity. Experiment 1 provided correlational evidence that individual differences in strategy adaptivity to changing base rates are related to individual differences in awareness of those changes but appear not to be related to individual differences in working memory capacity. Experiment 2 replicated the role of awareness, and the results suggest that awareness at the time of the base-rate change, rather than afterwards, is related to increased strategy adaptivity. Experiment 3 measured working memory capacity using a different procedure and manipulated working memory load with a dual-task procedure; again, no apparent role of working memory capacity in strategy adaptivity was found. This juxtaposition of findings presents a challenge for existing models of strategy choice.

Schunn, C.D. & Reder, L.M. (2001). Another source of individual differences: Strategy adaptivity to changing rates of success. Journal of Experimental Psychology: General, 130, 59-76. http://dx.doi.org/10.1037//0096-3445.130.159
  • Show abstract
    • To further the understanding of the mechanisms of strategy choice, in three experiments, we investigate the role of explicit awareness and working memory in strategy adaptivity. Experiment 1 provided correlational evidence that individual differences in strategy adaptivity to changing base rates are related to individual differences in awareness of those changes but appear not to be related to individual differences in working memory capacity. Experiment 2 replicated the role of awareness, and the results suggest that awareness at the time of the base-rate change, rather than afterwards, is related to increased strategy adaptivity. Experiment 3 measured working memory capacity using a different procedure and manipulated working memory load with a dual-task procedure; again, no apparent role of working memory capacity in strategy adaptivity was found. This juxtaposition of findings presents a challenge for existing models of strategy choice.

Simmons, M.R., Reder, L.M., & Fiez, J.A. (2001). The role of perceptual fan in explicit recognition: Functional neuroimaging evidence. Abstracts of the Eighth Annual Meeting of the Cognitive Neuroscience Society, New York NY.

Anderson, J.R., Greeno, J.G., Reder, L.M., & Simon, H.A. (2000). Perspectives on learning, thinking, and activity. Educational Researcher, 29(4), 11-13.
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    • We continue the discussion of cognitive and situative perspectives by identifying several important points on which we judge the perspectives to be in agreement: (1) Individual and social perspectives on activity are both fundamentally important in education; (2) Learning can be general, and abstractions can be efficacious, but they sometimes aren't; (3) Situative and cognitive approaches can cast light on different aspects of the educational process, and both should be pursued vigorously; (4) Educational innovations should be informed by the available scientific knowledge base and should be evaluated and analyzed with rigorous research methods.

Anderson, J.R., Reder, L.M., & Simon, H.A. (2000, Summer). Applications and misapplications of cognitive psychology to mathematics education. Texas Educational Review
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    • There is a frequent misperception that the move from behaviorism to cognitivism implied an abandonment of the possibilities of decomposing knowledge into its elements for purposes of study and decontextualizing these elements for purposes of instruction. We show that cognitivism does not imply outright rejection of decomposition and decontextualization. We critically analyze two movements which are based in part on this rejection--situated learning and constructivism. Situated learning commonly advocates practices that lead to overly specific learning outcomes while constructivism advocates very inefficient learning and assessment procedures. The modern information-processing approach in cognitive psychology would recommend careful analysis of the goals of instruction and thorough empirical study of the efficacy of instructional approaches.

Lovett, M.C., Daily, L.Z., & Reder, L.M. (2000). A source activation theory of working memory: Cross-task prediction of performance in ACT-R. Journal of Cognitive Systems Research, 99-118.
  • Show abstract
    • Over the decades, computational models of human cognition have advanced from programs that produce output similar to that of human problem solvers to systems that mimic both the products and processes of human performance. In this paper, we describe a model that achieves the next step in this progression: predicting individual participants' performance across multiple tasks after estimating a single individual difference parameter. We demonstrate this capability in the context of a model of working memory, where the individual difference parameter for each participant represents working memory capacity. Specifically, our model is able to make zero-parameter predictions of individual participants' performance on a second task after separately fitting performance on a preliminary task. We argue that this level of predictive ability offers an important test of the theory underlying our model.

Reder, L.M., Nhouyvansivong, A., Schunn, C.D., Ayers, M.S., Angstadt, P., & Hiraki, K. (2000). A mechanistic account of the mirror effect for word frequency: A computational model of remember/know judgments in a continuous recognition paradigm. Journal of Experimental Psychology: Learning, Memory, & Cognition, 26(2), 294-320.
  • Show abstract
    • A theoretical account of the mirror effect for word frequency and of dissociations in the pattern of responding Remember vs. Know (R vs. K) for low- and high-frequency words was tested both empirically and computationally by comparing predicted with observed data theory in 3 experiments. The SAC (Source of Activation Confusion) theory of memory makes the novel prediction of more K responses for high- than for low-frequency words, for both old and new items. Two experiments used a continuous presentation and judgment paradigm that presented words up to 10 times. The computer simulation closely modeled the pattern of results, fitting new Know and Remember patterns of responding at each level of experimental presentation and for both levels of word frequency for each participant. Experiment 3 required list discrimination after each R response (Group 1) or after an R or K response (Group 2). List accuracy was better following R responses. All experiments were modeled using the same parameter values.

Spehn, M.K. & Reder, L.M. (2000). The unconscious feeling of knowing: A commentary on Koriat's paper. Consciousness and Cognition, 9, 187-192.
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    • In Koriat's paper "The Feeling of Knowing: Some Metatheoretical Implications for Consciousness and Control," he asserts that the feeling of knowing straddles the implicit and explicit, and that these conscious feelings enter into a conscious control process that is necessary for controlled behavior. This assertion allows him to make many speculations on the nature of consciousness itself. We agree that feelings of knowing are produced through a monitoring of one's knowledge, and that this monitoring can affect the control of behavior such as whether or not to search memory for an answer. Further, we believe that monitoring of performance with a strategy can also affect cognition control and strategy selection; however, we also believe that frequently this monitoring and control occurs without conscious awareness. Feeling of knowing has received an inordinate amount of attention because it lies behind the highly recognizable tip-of-the-tongue phenomenon that represents one of the rare cases of conscious monitoring. There are other feelings of knowing which are much more common and are not accompanied by conscious awareness. These are evident in the early selection of a strategy for answering a problem. In our view, the research on feeling of knowing will not resolve the question of whether consciousness is merely epiphenomenal.


Anderson, J.R., & Reder, L.M. (1999). Process, not representation: Reply to Radvansky (1999). Journal of Experimental Psychology: General 128(2), 207-210.
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    • The size of fan effects is determined by processes at retrieval, not by whether or not information is represented as situations. Evidence contradicts G. A. Radvansky's (1999) claim that time to retrieve information from a situation does not depend on the number of elements in the situation. Moreover, Radvansky's principles for ascribing situational models to experiments appear to be post hoc ways of redescribing the data. On the other hand, the evidence does support the Adaptive Control of Thought - Rational (ACT-R) assumption that participants can adjust their attentional weightings and so produce differential fan effects. Moreover, the ACT-R theory of the fan effect is consistent with many other findings.

Anderson, J.R. & Reder, L.M. (1999). The fan effect: New results and new theories. Journal of Experimental Psychology: General, 128(2), 186-197.
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    • The fan effect (J. R. Anderson, 1974) has been attributed to interference among competing associations to a concept. Recently, it has been suggested that such effects might be due to multiple mental models (G. A. Radvansky, D. H. Spieler, & R. T. Zacks, 1993) or suppression of concepts (M. C. Anderson & B. A. Spellman, 1995; A. R. A. Conway & R. W. Engle, 1994). It was found that the Adaptive Control of Thought - Rational (ACT-R) theory, which embodies associative interference, is consistent with the results of G. A. Radvansky et al. and that there is no evidence for concept suppression in a new fan experiment. The ACT-R model provides good quantitative fits to the results, as shown in a variety of experiments. The three key concepts in these fits are (a) the associative strength between two concepts reflect the degree to which one concept predicts the other; (b) foils are rejected by retrieving mismatched facts; and (c) participants can adjust the relative weights they give to various cues in retrieval.

Lemaire, P. & Reder, L.M. (1999). What affects strategy selection in arithmetic? The example of parity and five effects on product verification. Memory & Cognition, 27(2), 364-382.
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    • The parity effect in arithmetic problem verificaiton tasks refers to faster and more accurate judgments for false equations when the odd/even status of the proposed answer mismatches that of the correct answer. In two experiments, we examined whether the proportion of incorrect answers that violated parity or the number of even operands in the problem affected the magnitude of these effects. Experiment 1 showed larger parity effects for problems with two even operands and larger parity effects during the second half of the experiment. Experiment 2 replicated the results of Experiment 1 and varied the proportion of problems violating parity. Larger parity effects were obtained when more of the false problems violated parity. Moreover, all three effects combined to show the greatest parity effects in conditions with a high proportion of parity violations in problems containing two even operands that were solved during the second half of the experiment. Experiment 3 generalized the findings to the case of five rule (i.e., checking whether a false product ends in 5 or 0), another procedure for solving and verifying multiplication problems quickly. These results (1) delineate further constraints for inclusion in models of arithmetic processing when thinking about how people select among verification strategies, (2) show combined effects of variables that traditionally have been shown to have separate effects on people's strategy selection, and (3) are consistent with a view of strategy selection that suggests a bias either in the allocation of cognitive resources in the execution of strategies or in the order of execution of these strategies; they argue against a simple, unbiased competition among strategies.

Lovett, M.C., Reder, L.M., & Lebiere, C. (1999). Modeling working memory in a unified architecture: An ACT-R perspective. In Miyake, A. and Shah, P. (Eds). Models of Working Memory. Cambridge University Press, 135-182.

Reder, L.M., & Schunn, C.D. (1999). Bringing together the psychometric and strategy worlds: Predicting adaptivity in a dynamic task. In Gopher, D. & Koriat, A. (Eds). Cognitive regulation of performance: Interaction of theory and application. Attention and Performance XVII., MIT Press, 315-342.
  • Show abstract
    • There are two traditional approaches to the study of individual differences in cognitive skill. One assumes that people differ in the strategies that they use. The other assumes that all people use the same strategies or processes but differ in one or more performance parameters affecting how these processes are executed (e.g. memory capacity). This chapter explores another possibility: that people differ in how well they adaptively shift strategies in response to changing features of the task environment. To test this, we examined the performance of 57 participants in a variation of the Kanfer-Ackerman Air Traffic Control Task (Kanfer and Ackerman, 1989), a dynamic task in which features of the environment frequently change. We found that, while most participants adapted their strategy selections in response to our manipulations of the task environment, not all participants were equally adaptive. Furthermore, using the CAM 4 (Kyllonen, 1993), a cognitive assessment battery, we were able to determine what cognitive subskills were associated with adaptiveness. In this context, we found that inductive reasoning skill (and not working memory, declarative learning, procedural learning, or processing speed) was associated with adaptiveness to our specific manipulations and to the general dynamic character of the air traffic control (ATC) task.

Anderson, J.R., Lebiere, C., Lovett, M.C., & Reder, L.M. (1998). ACT-R: A higher-level account of processing capacity. (Commentary on Halford, Wilson & Phillips, Processing capacity defined by relational complexity: Implications for comparative, developmental and cognitive psychology.) Behavioral and Brain Sciences, 831-832.
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    • We present an account of processing capacity in the ACT-R theory. At the symbolic level, the number of chunks in the current goal provides a measure of relational complexity. At the subsymbolic level, limits on spreading activation, measured by the attentional parameter W, provide a theory of processing capacity, which has been applied to performance, learning and individual differences data.

Anderson, J.R., Reder, L.M., & Simon, H.A. (1998). Radical constructivism and cognitive psychology. In Ravitch, D. (Ed). Brookings Papers on Education Policy: 1998. Washington, D.C. Brookings Institution, 227-255.
Also published in Chile in Spanish Translation (2001). Educacion: El constructivismo radical y la psicologia cognitiva. Estudios Publicos, 81, 89-127.

Ayers, M.S. & Reder, L.M. (1998). A Theoretical review of the misinformation effect: Predictions from an activation-based memory model. Psychonomic Bulletin & Review. 5(1), 1-21. [lead article]
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    • This article reviews the major empirical results and theoretical issues from over 20 years of research on people's acceptance of false information about recently experienced events (see, e.g., Loftus, 1975). Several theoretical perspectives are assessed in terms of their ability to account for the various and sometimes conflicting results in the literature. Theoretical perspectives reviewed include the trace alteration hypothesis, the blocking hypothesis, the task demands/strategic effects hypothesis, source monitoring, and an activation-based semantic memory account. On the basis of its ability to account for the reviewed data and other cognitive phenomena, an activation-based semantic network model of memory is suggested for understanding the data and planning future research in the area.

Best, B.J., Schunn, C.D., & Reder, L.M. (1998). Modeling adaptivity in a dynamic task. In M.A. Gernsbacher & S. J. Derry (Eds.), Proceedings of the Twentieth Annual Conference of the Cognitive Science Society, (144-159). Mahwah, NJ: Erlbaum.
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    • Adaptivity is examined within a complex task environment: the Kanfer-Ackerman Air Traffic Controller Task©. A computational model is developed in ACT-R to account for such adaptivity using an implicit learning mechanism.

Delaney, P., Reder, L.M., Staszewski, J., & Ritter, F. (1998). The strategy specific nature of improvement: The power law applies by strategy within task. Psychological Science, 9(1), 1-7. [lead article]
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    • If strategy shifts speed up performance, learning curves should show discontinuities where such shifts occur. Relatively smooth curves appear consistently in the literature, however. To explore this incongruity, we examined learning when multiple strategies were used. We plotted power law learning curves for aggregated data from four mental arithmetic experiments and then plotted similar curves separately for each participant and strategy. We then evaluated the fits achieved by each group of curves. In all four experiments, plotting separately by strategy produced significantly better fits to individual participants' data than did plotting a single power function. We conclude that improvement of solution time is better explained by practice on a strategy than by practice on a task, and that careful assessment of trial-by-trial changes in strategy can improve understanding of the effects of practice on learning.

Erickson, M.A. & Reder, L.M. (1998). The influence of repeated presentations and intervening trials on negative priming. In M.A. Gernsbacher & S. J. Derry (Eds.), Proceedings of the Twentieth Annual Conference of the Cognitive Science Society, (327-332). Mahwah, NJ: Erlbaum.
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    • The effects of repeating a task-irrelevant element and inserting intervening trials between the last prime and the probe trial in a negative priming study were compared with a standard prime/probe pair. An associative model based on SAC (e.g. Reder & Schunn, 1996; Schunn, Reder, Nhouyvanisvong, Richards & Stroffolino, 1997) was able to account for both the decrease in response times across the repeated primes and the increase in response times when the task-irrelevant element became relevant.

Nhouyvanisvong, A. & Reder, L.M. (1998). Rapid feeling-of-knowing: A strategy selection mechanism. In: Yzerbyt, V. Y., Lories, G., Dardenne, B. (Eds.), Metacognition: Cognitive and social dimensions. London: Sage, 35-52.

Schunn, C.D. & Reder, L.M. (1998). Strategy adaptivity and individual differences. In D. L. Medin (Ed.) The Psychology of Learning and Motivation, Academic Press, 115-154.

Anderson, J.R., Reder, L.M., & Simon, H.A. (1997). Situative versus cognitive perspectives: Form versus substance. Educational Researcher, 26(1), 18-21.

Lovett, M.C., Reder, L.M., & Lebiere, C. (1997). Modeling individual differences in a digit working memory task. Proceedings of the Nineteenth Annual Cognitive Science Conference, 460-465. Mahwah, NJ: Erlbaum.
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    • Individual differences in working memory are an important source of information for refining theories of memory and cognition. Computational modeling is an effective tool for studying individual difference because it allows researchers to maintain the basic structure of a theory while perturbing a particular component. This paper presents a computational model for a digit working memory task and demonstrates that varying a single parameter captures individual differences in that task. The model is developed within the framework of the ACT-R theory (Anderson, 1993), and the continuous parameter manipulated represents attentional capacity for the current goal.

Reder, L.M. & Gordon, J.S. (1997). Subliminal perception: Nothing special, cognitively speaking. In J. Cohen and J. Schooler (Eds.) Cognitive and Neuropsychological approaches to the study of Consciousness, Mahwah, New Jersey: L. Erlbaum, 125-134.

Reder, L.M., Nhouyvansivong, A., Schunn, C.D., Ayers, M.S., Angstadt, P., & Hiraki, K. (1997). Modeling word frequency effects in a continuous remember/know judgment paradigm. Proceedings of the Nineteenth Annual Cognitive Science Conference, 644-649. Mahwah, NJ: Erlbaum.
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    • Words of varying pre-experimental frequency were presented up to 10 times each. On each presentation, three responses were allowed - new, remember, and know - the last for words that seem familiar, but give no consciosu recollection of an earlier presentation. A novel pattern of results was predicted by the SAC memory model. SAC used the same parameter values used in fits to other tasks and provided good fits to the participants' remember and know responses.

Schunn, C.D., Reder, L.M., Nhouyvanisvong, A., Richards, D.R., & Stroffolino, P.J. (1997). To calculate or not calculate: A source activation confusion (SAC) model of problem-familiarity's role in strategy selection. Journal of Experimental Psychology: Learning, Memory, & Cognition, 23, 1-27. [lead article]
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    • How do people decide whether to try to retrieve an answer to a problem or to compute the answer by some other means? The authors report 2 experiments showing that this decision is based on problem familiarity rather than on retrievability of some answer (correct or incorrect), even when problem familiarization occurred 24 hr earlier. These effects at the level of the individual problem solver and the results reported by L. M. Reder and E E. Ritter (1992) are well fit with the same parameter values in a spreading-activation computational model of feeling of knowing in which decisions to retrieve or compute an answer are based on the familiarity or activation levels of the problem representation. The authors therefore argue that strategy selection is governed by a familiarity-based feeling-of-knowing process rather than by a process that uses the availability of the answer or some form of race between retrieving and computing the answer.

Anderson, J.R., Reder, L.M., & Lebiere, C. (1996). Working memory: Activation limitations on retrieval. Cognitive Psychology, 30, 221-256.
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    • Two experiments which require subjects to hold a digit span while solving an equation and then recall the digit span are performed. The size of the memory span and the complexity of the equation are manipulated as well as whether the subject is required to substitute items from the digit span for constants in the equation. As either task (digit span recall or equation solving) gets more complex there are performance decrements (accuracy or latency) not only in that task but also in the other task. It is also shown that the majority of the errors are misretrievals. These results are consistent with the proposal that working memory load has its impact on retrieval from memory. These results are fit by the ACT-R theory (Anderson, 1993) which assumes that there is a limit on source activation and that this activation has to be divided between the two tasks. As either task increases in complexity there is less activation for retrieval of information from declarative memory. Subjects' misretrievals of associatively related information could be predicted by assuming a partial matching process in ACT-R.

Anderson, J.R., Reder, L.M., & Simon, H.A. (1996). Situated learning and education. Educational Researcher, 25(4), 5-11. [lead article]
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    • This paper presents a review of the claims of situated learning that are having an increasing influence on education generally and mathematics education particularly. We review the four central claims of situated learning with respect to education: (1) action is grounded in the concrete situation in which it occurs; (2) knowledge does not transfer between tasks; (3) training by abstraction is of little use; and (4) instruction must be done in complex, social environments. In each case, we cite empirical literature to show that the claims are overstated and that some of the educational implications that have been taken from these claims are misguided.

Kamas, E., Reder, L.M., & Ayers, M. (1996). Partial matching in the Moses illusion: Response bias not sensitivity. Memory and Cognition, 24, 687-699. [lead article]
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    • Previous research has demonstrated that people have enormous difficulty in detecting distortions in such questions as, "How many animals of each kind did Moses take on the Ark?" Reder and Kusbit (1991) argued that the locus of the effect must be the existence of a partial-match process. Other research has suggested that this partial-match process operates at the word level and that, with adequate focus on the relevant word, the Moses Illusion is greatly diminished. The present experimental results argue that those conclusions were based in a shift in response criterion with no concomitant change in ability to detect distortions. Furthermore, the data suggest that the matching process operates below the word level, at the level of distinctive features.

Reder, L.M. (1996). Different research programs on metacognition: Are the boundaries imaginary? Commentary for special issue of Learning and Individual Differences., 8(4), 383-390.
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    • This commentary asks whether the term "metacognition" means different things to researchers working in different subareas of cognitive and developmental psychology or whether they are just studying different aspects of the same underlying construct. The four articles in this special issue seem to be addressing phenomena that frequently share little except a label. Some of the phenomena that are called metacognitive necessarily involve conscious processing; however, other phenomena addressed in this issue, such as self-regulating behaviors, are typically executed without conscious awareness.

Reder, L.M. (Ed.) (1996). Implicit Memory and Metacognition. Mahwah, N.J.: L. Erlbaum.
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Reder, L.M. & Schunn, C.D. (1996). Metacognition does not imply awareness: Strategy choice is governed by implicit learning and memory. In Reder, L.M., (Ed.) Implicit Memory and Metacognition. Mahwah, N.J.: L. Erlbaum, 45-77.

Schooler, J.S., Ryan, R., & Reder, L.M. (1996). The costs and benefits of verbally rehearsing memory for faces. In D.J. Herrmann, M.K. Johnson, C. Hertzog, C. McEvoy & P. Hertel (Eds.) Basic and Applied Memory Research, Vol. II. Hillsdale, N.J.: L. Erlbaum, 51-65.

Schunn, C.D. & Reder, L.M. (1996). Modeling changes in strategy selections over time. Proceedings of the AAAI-96 Workshop on Computational Cognitive Modeling. Portland, Oregon, August 1996.
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    • In this paper we present a method for fitting strategy choice data at the individual subject/individual trial level, and demonstrate, using the SAC model, that good fits to data can be obtained at this level. We conclude by discussing the sources of power in using this method.

Kamas, E. & Reder, L.M. (1994).The role of familiarity in cognitive processing. In: E. O'Brien, and R. Lorch (Eds.), Sources of coherence in reading: A festschrift in honor of Jerome L. Myers. New Jersey: L. Erlbaum, 177-202

Lebiere, C., Anderson, J.R., & Reder, L.M. (1994). Error modeling in the ACT-R production system. Proceedings of the Cognitive Science Society, Atlanta, Georgia.
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    • We describe how to extend the ACT-R production system to model human errors in the performance of a high-level cognitive task: to solve simple linear algebra problems while memorizing a digit span. Errors of omission are produced by introducing a cutoff on the latency of memory retrievals. If a memory chunk cannot gather enough activation to be retrieved before the threshold is reached, retrieval fails. Adding Gaussian noise to chunk activation produces a pattern quantitatively similar to subject errors. Errors of commission are introduced by allowing imperfect matching in the condition side of productions. The wrong memory chunk can be retrieved if its activation is large enough to allow it to overcome the mismatch penalty. This mechanism provides a qualitative and quantitative fit to subject errors. In conclusion, this paper demonstrates that human-like errors, sometimes thought of as the exclusive domain of connectionist models, can be successfully duplicated in production system models.

Miner, A. & Reder, L.M. (1994). A new look at feeling of knowing: Its metacognitive role in regulating question answering. In: Metcalfe, J. and Shimamura, A. (Eds). Metacognition: Knowing about knowing. Cambridge, Mass: MIT Press.
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    • This book has approached metacognition, control strategies and knowledge about the process of knowing, from various perspectives ranging from neurological to developmental. This chapter is going to focus on one particular metacognitive process in adults, the "feeling of knowing" process. The discussion of feeling of knowing will begin by examining the phenomenon itself, beginning with early explorations leading to present research, then will explore underlying mechanisms, and, finally, will consider the functional utility of this process. Our argument will be that feeling of knowing shoudl be reconceptualized as a rapid, pervasive process beginning prior to actual memory retrieval. Such a reconceptualization should clarify the metacognitive role of feeling of knowing and emphasize its importance as a central rather than an incidental process in cognition.

Reder, L.M. & Klatzky, R. (1994). Transfer: Training for performance. In Druckman, D. & Bjork, R.A. (Eds.) Learning, Remembering, Believing: Enhancing team and individual performance. Washington, D.C.: National Academy Press.

Reder, L.M. & Ritter, F. (1992). What determines initial feeling of knowing? Familiarity with question terms, not with the answer. Journal of Experimental Psychology: Learning, Memory, and Cognition, 18, 435-451. [lead article]
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    • How do people know whether they have an answer to a question before they actually find it in their memory? We conducted 2 experiments exploring this question, in which Ss were trained on relatively novel 2-digit x 2-digit arithmetic problems (e.g. 23 x 27). Before answering each problem, Ss made a quick feeling of knowing judgment as to whether they could directly retrieve their answer from memory or had to compute it. Knowing the answer initially appeared to be linearly related to having a feeling of knowing the answer; however, when the frequency of exposure to complete problems and the frequency of exposure to parts of the problems were separately varied, feeling of knowing was better predicted by the frequency of the presentation of the problem parts, not by knowledge of the answer. This suggests that the process involved in knowing the answer are different from those involved in having a feeling of knowing. Specifically, an early feeling of knowing is not just based on an early read of the answer.

Charney, D.H., Reder, L.M., & Kusbit, G.W. (1991). Improving documentation with hands-on problem solving. Proceedings of "Documentation: The First Conference on Quality" sponsored by the Centre for Professional Writing, University of Waterloo, Canada.

Reder, L.M. & Kusbit, G.W. (1991). Locus of the Moses illusion: Imperfect encoding, retrieval or match? Journal of Memory and Language, 30, 385-406. [lead article]
  • Show abstract
    • Five experiments are described that attempt to isolate the mechanism that produces the failure to notice discrepancies in questions or assertions, called the Moses Illusion (T. A. Erickson & M. E. Mattson, 1981. Learning and Verbal Behavior, 20, 540-552). Experiments 1 through 5 involved asking subjects to either (1) discriminate between distorted questions such as "How many animals of each kind did Moses take on the ark?" or (2) ignore the distortions and answer the question as if it were perfectly formed. Experiments 2, 3, and 5 also varied the familiarity of the assertions that were queried. Experiments 4 and 5 recorded the reading times of the words in the question as well. Four alternative explantions for the Moses Illusion are considered: (1) the so-called illusion is just a cooperative response adopted by the listener/reader; (2) the retrieved memory structures are impoverished or incomplete and thus the discrepancies cannot be detected; (3) the question is not carefully encoded and therefore the distorted word may not be fully processed during encoding; and (4) people often do incomplete matches between a complete representation of the question and a complete representation of the stored proposition that contains the answer. The evidence from these experiments does not support the first three alternatives, but is consistent with the partial-match hypothesis.

Reder, L.M., & Cleeremans, A. (1990). The role of partial matches in comprehension: The Moses illusion revisited. In A. Graesser & G. Bower, (Eds.), The Psychology of Learning and Motivation, Vol. 25, New York: Academic Press, 233-258.

Charney, D.H., Reder, L.M., Kusbit, G.W. (1990). Goal setting and procedure selection in acquiring computer skills: A Comparison of tutorials, problem-solving, and learner exploration. Cognition and Instruction, 7(4), 323-342.
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    • This study investigated the relative benefits for acquiring computer skills of: (1) learner-initiated versus experimenter-supplied goals and (2) active practice at selecting and applying procedures versus directed execution of procedures. Subjects with varied computer experience but no knowledge of electronic spreadsheets were randomly assigned to an interactive instruction or exploratory learning condition. Both groups read identical descriptions of 12 spreadhseet commands. The exploration learning group experimented with commands at will, setting goals, and selecting and applying procedures. The interactive instruction group did not select their own goals, but instead worked three training problems per command. The training problems for six commands were presented without solutions; subjects solved them by actively selecting and applying procedures, and afterwards received feedback. For the remaining six commands, the training problems were tutorials with explicit solutions that subjects typed in verbatim. Two days after training, all subjects solved 12 test problems. Learning commands by solving problems without explicit solutions led to longer training times, but also significantly faster and more performance at test than either tutorial training or exploration learning. Exploration learning did not differ significantly from tutorials in training time or performance at test. Regression analyses indicated that the advantage of problem solving was not simply due to longer training times.


Charney, D.H., Reder, L.M., & Wells, G.W. (1988). Studies of elaboration in instructional texts. In S. Doheny-Farina (Ed.), Effective documentation: What we have learned from research, Cambridge, Mass: MIT Press, 47-72. 
Note: Above paper was the winner of the 1989 NCTE Award for Excellence in Technical and Scientific Writing: Best Article Reporting Formal Research in Technical or Scientific Communication. 
  • Show abstract
    • Technical writers who must produce a manual or some other instructional text are often caught between conflicting goals. On one hand, as advocates of the readers who must understand and use the text, writers worry about leaving out any bit of information that might be important or useful. On the other hand, as employees who are accountable for producing a text at the least possible cost, they must use text sparingly: The longer the text, the higher the cost. In short, writers must constantly judge whether the importance of an explanation or some other piece of information is worth the cost of printing it. In some sense, all writers face the same fundamental question: what information should a text contain and to what extent should that information be elaborated?
      In this chapter, we review several years of experimental research on this question of content and elaboration. Obviously, there can be no absolute answers to such questions. The answers must depend on factors such as the writer's purpose, the readers' intentions and abilities (i.e., their reasons for reading and their prior familiarity with the subject matter), and general human capacities for acquiring information or skills, in addition to conventional constraints on the form of the text. To narrow down the question to manageable proportions, we have focused our research primarily on individuals reading in order to learn a skill. Specifically, we focus on people who are learning to use a computer by reading a user manual.
      The general strategy for our research has been to produce several versions of a computer manual that differ in systematic ways. We asked participants (generally college students) to work through the manuals. In some studies, we simply had participants read the manual; in others, participants also learned by working interactively with the computer. After removing the manuals, we asked the participants to demonstrate what they had learned by performing a set of tasks on the computer. We observed how many tasks the participants completed successfully and how long it took them to do so. By comparing the performance of participants who read the different versions of the manual, we can draw inferences about the characteristics of manuals that lead to better performance. We also employed a variety of readers in our studies: experienced computer users as well as computer novices, readers who opened a manual with a particular task in mind as well as readers who had no particular agenda. By comparing the performance of these groups of readers, we can draw inferences about the different needs of different readers.

Reder, L.M. (1988). Strategic control of retrieval strategies. In G. Bower (Ed.), The Psychology of Learning and Motivation, Vol. 22, New York: Academic Press, 227-259.

Anderson, J.R., & Reder, L.M. (1987). Effects of number of facts studied on recognition versus sensibility judgments. Journal of Experimental Psychology: Learning, Memory, and Cognition, 13(3), 355-367. [lead article]
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    • The effect of memory representation on the ease of cognitive judgments can vary depending on the nature of the judgment required. In three experiments, subjects studied sets of sentences and in later phases made recognition judgments or sensibility judgments on those sentences and others constructed from the words in the sentences they had studied. In Experiments 1 and 2, the studied sentences were sensible, whereas in Experiment 3 the studied sentences were nonsensical. Judgment times varied with the fan of the concepts in the sentence (i.e., the number of facts known about each concept). Subjects were slowed by fan in retrieving a specific fact but speeded by fan in making a sensibility judgment. In all experiments, subjects were faster at making a judgment in conditions where judgments could be made either by a memory retrieval process or a semantic sensibility process. This implies that subjects can sometimes recognize that they have studied a sentence before they can judge its sensibility. This result calls into question the view that language processing is a faculty that occupies a place separate from memory.

Charney, D.H. & Reder, L.M. (1987). Initial skill learning: An analysis of how elaborations facilitate the three components. In P.E. Morris (Ed.), Modeling Cognition, London: Wiley Publishers, 135-165.

Reder, L.M. (1987). Beyond associations: Strategic components in memory retrieval. In D. Gorfein & R. Hoffman (Eds.), Memory and Learning: The Ebbinghaus Centennial Conference, Hillsdale, NJ: Lawrence Erlbaum Associates, 203-220.

Reder, L.M., (1987). Strategy selection in question answering. Cognitive Psychology, 19(1), 90-138.
Note: Above paper was reprinted in T.O. Nelson, (1992) Metacognition: Core Readings, Allyn & Bacon Publishers.
  • Show abstract
    • There are multiple strategies for answering questions. For example, a statement is sometimes verified using a plausibility process and sometimes using a direct retrieval process. It is claimed that there is a distinct strategy selection phase and a framework is proposed to account for strategy selection. Six experiments support the assumptions of the proposed framework: The first three experiments show that strategy selection is under the strategic control of the subjects. These experiments also indicate what contextual variables affect this selection. Experiments 4 and 5 suggest that strategy selection also involves evaluating the question itself, while experiment 6 suggests variables that influence the evaluation of the question. This model is shown to be consistent with processing strategies in domains other than question answering, viz., dual-task monitoring in divided attention situations.

Charney, D.H., & Reder, L.M. (1986). Designing tutorials for computer users: Effects of the form and spacing of practice on skill learning. Human Computer Interaction, 2, 297-317.
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    • The aim of this article is to find the optimal combination of written instruction and on-line practice for learning a new computer application. Subjects in the experiment learned commands for an electronic spreadsheet by reading brief user-manual descriptions and working training problems on-line. The form of the training problems was varied in a within-subjects design to control how much independent problem solving subjects engaged in while learning any given command. There were three forms of practice: (a) pure guided practice, in which subjects were told exactly what keystrokes to type to solve the problems; (b) pure problem-solving practice, in which subjects solved problems without guidance; and (c) mixed practice, in which the first problem for a command was presented in guided practice form and two others in problem-solving form. The spacing of the training problems was also manipulated; the problems pertaining to a given command were either massed (i.e., presented consecutively) or distributed (i.e., separated by other instructional material). After a 2-day delay, subjects now solved new problems on the computer without referring to the instructional materials. The results indicate that problem-solving was a more difficult form of training than guided practice, but it produced the best performance at test. Distributing the spacing of training problems during training also improved performance at test. The results have clear pragmatic implications for the design of interactive tutorial manuals as well as implications for cognitive models of skill acquisition.

Reder, L.M., Charney, D.H., & Morgan, K.I. (1986). The role of elaborations in learning a skill from an instructional text. Memory and Cognition, 14(1), 64-78.
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    • In these studies, we examined the role of elaborations for subjects learning a procedural skill (viz., using a personal computer) from an instructional text. In Experiment 1, we compared two sources of elaborations: those provided by the author and those generated by learners while reading. In the latter condition, subjects were given advance information about the tasks they were to perform so that they would generate more specific task-related elaborations while reading. Each source of elaborations facilitated skill performance. This result constrasts with results of the past experiments testing declarative knowledge in which author-provided elaborations were found to hurt performance. In Experiment 2, the author-provided elaborations were classified into those illustrating the syntax of the operating system commands and those explaining basic concepts and their applicability. Syntax elaborations produced significant facilitation for experienced and novice computer users. Concept elaborations produced no reliable improvement.

Reder, L.M., Wible, C., & Martin, J. (1986). Differential memory changes with age: Exact retrieval versus plausible inference. Journal of Experimental Psychology: Learning, Memory, and Cognition, 12(1), 72-81.
Note: Above paper was reprinted in L. Komatsu (1994), Experimenting with the mind: Readings in cognitive psychology, Brooks/Cole.
  • Show abstract
    • Elderly and college-age subjects were compared in two experiments, one involving episodic memory and one involving semantic memory. Responses were generally slower for older subjects; however, in some conditions, older subjects were as good as or better than younger subjects, even in terms of response time. The results suggest that older subjects have no difficulty with memory tasks that do not require exact memory-matches or careful inspection of retrieved propositions. It is argued that careful inspection is a much more costly process for older adults than it is for young adults, but that plausibility judgments and feature overlap processes are equally easy for both age groups. The suggestion is made that older subjects also tend to modify their performance in ways that would minimize the detrimental effects of forgetting specific facts.

Reder, L.M. (1985). Techniques available to author, teacher and reader to improve retention of main ideas of a chapter. In S. Chipman, J. Segal, & R. Glazer (Eds.), Thinking and learning skills: Current research and open questions, Vol. 2. Hillsdale, NJ: Lawrence Erlbaum Associates, 37-64.
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    • This chapter is concerned with possible devices to improve the communication of ideas of the author to the prospective reader. Most of the proposed ideas are intended for the author to incorporate into plans for writing a chapter; however, some points suggest techniques the reader could employ when reading a text, and there are also suggestions that a teacher could use to improve a student's learning from the available material.
      A brief review is given of some of the past work on how to improve retention of the important ideas from a text. This research is largely concerned with the effects of advance organizers as well as questions posed before and after reading. Two theoretical explanations are offered for the effectiveness of the various manipulations-the Focus Hypothesis and the Elaboration Hypothesis. Arguments along with empirical data are offered to bolster each position.
      A series of experiments is described that indicates that people learn the central ideas of a chapter more effectively when they read a summary version than when they read the original, embellished text. These data argue for the focus interpretation. Other data suggest that elaborations aid retention. An attempt is made to reconcile these somewhat contradictory findings.
      It is suggested that the elaborations provided by the reader are often more effective than those provided by the author. This is due to the inherent value of integrative processing (i.e. being forced to generate one's own embellishments) and due to the poor quality of many author-provided elaborations. An implication of this notion is that authors should provide better embellishments of the central ideas or skip writing embellishments at all. It is also suggested that authors present their ideas in a top-down fashion, repeating more than once, each time giving more detail. The ideas in this chapter are presented several times, each time with more detail.

Reder, L.M., & Wible, C. (1984). Strategy use in question-answering: Memory strength and task constraints on fan effects. Memory and Cognition, 12, 411-419.
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    • The time taken to recognize a studied fact increases as a function of the number of other previously studied facts sharing concepts with the test fact. The phenomenon, known as the "fan effect," has been shown to disappear and sometimes even reverse itself when the set of facts are thematically related. The shift from interference to facilitation occurs only when subjects can use a plausibility-like strategy. In this experiment, subjects learned variously sized sets of related facts about fictitious people. Subjects were asked to make either recognition judgments ("Did you study this fact?") or consistency judgments ("Is this fact consistent with what you studied?"). Subjects made these judgments both the day the material was acquired and 2 days later. The research reported here supports the hypothesis that, with delay, there is a shift in tendency toward mroe use of the plausibility strategy, away from the careful strategy of searching for an exact match that produces the fan effect. The plausibility strategy produced either a speedup with greater fan or an increase in error rates when the strategy was inappropriate. Plausibility effects were larger at a delay, in both reaction time and error patterns, regardless of whether subjects were asked to make consistency judgments or recognition judgments. Also as predicted, response times became faster as the tendency to adopt the plausibility strategy without first trying direct retrieval increased.

Reder, L.M. (1983). What kind of pitcher can a catcher fill? Effects of priming in sentence comprehension. Journal of Verbal Learning and Verbal Behavior, 22, 189-202.
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    • Subjects read sentences that ended in an ambiguous noun that had been disambiguated by preceding selectinoal restrictions. Each sentence began with a subject noun and a relative clause that could either prime the selected meaning of the final word, the nonselected meaning, or neither. Three experiments used comprehension time and interpretation errors to determine how context integrates with selectional restrictions. There were effects of positive priming on comprehension time and effects of negative priming on interpretation errors. The effects of priming were additive. These results support a threshold model of concept activation.

Reder, L.M. & Ross, B.H. (1983). Integrated knowledge in different tasks: The role of retrieval strategy on fan effects. Journal of Experimental Psychology: Learning, Memory and Cognition, 9, 55-72.
  • Show abstract
    • Prior research has shown that the fan effect (slower response times [RTs] to verify facts when more are studied on a topic) is attenuated when thematically related facts are used. This alleviation of interference occurs only when subjects can use consistency judgments instead of direct retrieval to make recognition judgments. Exploring this issue further, we discovered that knowing additional facts relevant to the test fact can actually speed judgment times when subjects are asked whether the test fact is consistent with what is known rather than if it had been studied. The same subjects displayed three different RT functions for the same memory items when they performed in three different test blocks intended to invoke three different strategies. We also varied the number of topics studied about fictitious characters while holding constant the number of total facts. Unlike simple fan, we found that the greater the number of topics studied with a character, the longer subjects took to respond, regardless of the strategy used in that test block. We present a model that is in accord with this pattern of data.

Allwood, C.M., Wikstrom, T., & Reder, L.M. (1982). The effects of text structure on free recall: More support for summaries. Poetics, 11, 145-153.
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    • Prior research (Reder and Anderson 1980, 1982) has shown that acquisition of new information can be facilitated by a format that summarizes the important points as compared with a more traditional format, such as a textbook chapter. The previous results used recognition (true/false tests) and cued recall (who did what?) measures. The experiment reported here investigated whether the detrimental effects of details in texts are compensated by their facilitory effects in providing additional retrieval routes. This was tested by using a free recall paradigm. Once again, summaries resulted in superior memory for the main points. Possible explanations and pedagogical implications are discussed. The quality of elaborations in texts and the ease of generating well organized representations from different formats may both affect performance.

Reder, L.M. (1982). Elaborations: When do they help and when do they hurt? Text, 2, 211-224.
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    • Theories of memory and text processing have begun to emphasize the important role of elaborative processing. The support for this role is tenuous, most of it being correlational. Few studies have been concerned with whether or not memory is better when the author (or experimenter) provides the embellishment. Most have only looked at effects of elaboration when the reader generates embellishments, possible confounding degree of effort with degree of elaboration. Experiments are described here where the elaborations are given to the reader. The paper specifies those situations where memory is improved by elaborations, and those that hurt retention.

Reder, L.M. (1982). Plausibility judgments vs. fact retrieval: Alternative strategies for sentence verification. Psychological Review, 89, 250-280.
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    • This article contrasts two views about how people judge the truth of statements. The more common view maintains that people decide whether a statement is true by finding a close (propositional) match to the query in memory; only if that fact cannot be found do they try to infer whether the statement is true by judging whether it is plausible. The second view, developed and argued in this article, is that judging plausibility is a more efficient strategy than direct retrieval (finding a propositional match), except when verbatim memory is very good. A model is proposed that exemplifies the second view. It is assumed that a person can evaluate a statement either by plausibility judgment or by direct retrieval. Both strategies consist of two major stages: searching for needed information and evaluating the adequacy of the retrieved information. Only when verbatim traces are strong, at very short delays after acquisition, is direct retrieval faster than judging plausibility. Direct retrieval becomes a less efficient strategy than plausibility judgment over time because the search stage becomes very long. Regardless of the ostensive task asked of a person, whether recognition or plausibility judgment, people use both strategies to answer questions. A person's preference for a particular strategy depends in part on task demands and in part on delay. Data are described from several experiments that support these theoretical positions and the data are fit by a formal model.

Reder, L.M. & Anderson, J.R. (1982). Effects of spacing and embellishments on memory for the main points of a text. Memory and Cognition, 10, 97-102. [lead article]
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    • An advantage has been found for acquiring textbook knowledge by studying textbook summaries rather than reading the original prose (Reder & Anderson, 1980). Three studies are presented that help to establish the cause of the summary advantage. One possible cause is that reading summaries allows the subject to reread the main points at spaced intervals, and spaced practice is superior to massed practice. A second possible cause is that the presence of details distracts the subject's attention away from the critical ideas that should be attended to. In Reder and Anderson (1980), these two factors were confounded, but they are unconfounded in the present studies. The results indicate that both possible causes, spaced practice and the absence of details, have significant, independent and positive effects on retention of the central ideas of a passage.

Reder, L.M. & Ross, B.H. (1981). The effects of integrated knowledge on fact retrieval and consistency judgments: When does it help, and when does it hurt. Proceedings of the Cognitive Science Society, Berkeley.
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Reder, L.M. (1980). The role of elaboration in the comprehension and retention of prose: A critical review. Review of Educational Research, 50, 5-53. [lead article]
  • Show abstract
    • A review is given of recent research done in the area of prose comprehension, broadly defined. Research in the areas of educational psychology, psychology, and artificial intelligence is represented, although no pretense is made that this review is complete. This review discusses work concerned with factors that affect amount of recall, with representations of text structures, and with use of world knowledge to aid comprehension. The need for more information processing models fo comprehension is stressed and an argument is made for the importance of elaboration to comprehension and retention.

Reder, L.M. & Anderson, J.R. (1980). A comparison of texts and their summaries: Memorial consequences. Journal of Verbal Learning and Verbal Behavior, 19, 121-134. [lead article]
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    • Chapters from college textbooks in diverse fields were compared with summaries constructed to convey the main points. A series of studies demonstrate consistent advantages for summaries. Summaries maintained their advantages at retention intervals of 20 minutes, 1 week, and 6 to 12 months. Summaries were superior both for questions directly taken from the text and for inference questions that required the subject to combine facts that had been studied. A transfer task looked at ability to learn new, related material as a function of how the previous material was learned. Summaries yielded better transfer. Reaction time differences showed the same pattern as percentage correct. Summaries maintained their superiority even when the main points in the text were underlined.

Reder, L.M. & Anderson, J.R. (1980). A partial resolution of the paradox of interference: The role of integrating knowledge. Cognitive Psychology, 12, 447-472. [lead article]
  • Show abstract
    • It has been noted that models of memory that posit retrieval interference imply that the more one knows about a topic, the harder it is to retrieve any one of these facts. Smith, Adams, and Schorr (Cognitive Psychology, 1978, 10, 438-464) regard this to be a paradox and postulate that people use world knowledge to integrate various facts about a concept and thereby avoid interference. Exploring this issue further in two experiments we discovered that integration of facts alleviates interference only when a person can perform his memory task by simply making a consistency judgment and can avoid the need to retrieve a specific fact. When foils force subjects to retrieve the specific assertion, the interference occurs among integrated facts as among unrelated facts. It appears that, when possible, subjects will judge whether they have seen a fact simply by judging if it is related to (consistent with) a theme they have studied. In other words, people judge themes rather than facts. Consistent with this interpretation, we found interference among themes; that is, the more themes were associated with a concept, the greater the interference.


Anderson, J.R. & Reder, L.M. (1979). An elaborative processing explanation of depth of processing. In L.S. Cermak & F.I.M. Craik (Eds.), Levels of processing in human memory. Hillsdale, NJ: Lawrence Erlbaum Associates, 385-403.
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    • The purpose of this paper is to discuss a theoretical view that we think accounts for the results that have been organized under the rubric of "depth of processing" (to be called DOP). We argue that the variation in memory with DOP is a result of the number of elaborations subjects produce while studying the material, that these elaborations establish mroe redundant encodings of the to-be-remembered information, and that elaboration is what is critical, especially for long-term retention. Because extent of elaboration is the critical variable, a better spatial metaphor for the DOP phenomena might be "breadth of processing." We argue that depth of processing is as important to prose material as it is to the verbal learning material with which DOP is most commonly studied. With prose, elaborations take on another dimension of importance: They prove to be critical to the comprehension of the material. We make these points about elaboration, DOP, and prose processing with linguistic examples and interpretations of empirical results.

Reder, L.M. (1979). The role of elaborations in memory for prose. Cognitive Psychology, 11, 221-234.
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    • In two experiments, subjects read stories and were asked to make plausibility judgments about statements with respect to the stories. The inherent plausibility of the queried statements, the amount of attention subjects focused on information necessary for making a judgment, and the interval between presentation of the relevant story information and the test probe were varied orthogonally. The pattern of latencies obtained to make these judgments cast strong doubt on the notion that question answering is typically accomplished by searching for a single fact in memory. Rather, people seem to retrieve any relevant, available information and then use this to compute whether a statement seems true. The independent variables in these experiments can be interpreted according to whether they affect the retrieval or the judgment phase.

Reder, L.M. & Anderson, J.R. (1979). Use of thematic information to speed search of semantic nets. Proceedings of the 6th International Joint Conference on Artificial Intelligence.
  • PDF not available.

Smith, E.E., Haviland, S.E., Reder, L.M., Brownell, H., & Adams, N. (1976). 
When preparation fails: Disruptive effects of prior information on perceptual recognition. Journal of Experimental Psychology: Human Perception and Performance, 2, 151-161. [lead article]
  • Show abstract
    • There is a conflict in the literature on selective attention. Suppose a subject is briefly presented an item followed by a multiple-alternative recognition test. If the items are pictures, the subject's performance is facilitated by presenting the alternatives beforehand (a before facilitation), but when the items are letters the subject's performance is disrupted by presentin the alternatives beforehand (a before disruption). Five experiments were conducted to resolve this conflict, and all involved a comparison of tachistoscopic recognition when alternatives were either presented beforehand or not. The first two studies showed that the before disruption with letters was not due to to certain task parameters. Experiments 3-5 demonstrated that this effect was due to masking conditions. Experiments 3 and 4 revealed that the disruption occurred only when a mask is used, while the last experiment indicated the disruption effect was sensitive to the type of mask employed. Presumably, the before disruption arises because a subject erroneously considers the features of a mask along with those of the test item in arriving at a perceptual decision.

Reder, L.M., Anderson, J.R., & Bjork, R.A. (1974). A semantic interpretation of encoding specificity. Journal of Experimental Psychology, 102(4), 648-656.
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    • Two experiments are presented to clarify possible interpretations of the Encoding Specificity Principle of Tulving and Thomson. This principle states that a cue must have been studied with a word in order for the cue to be effective at testing. In the experiments reported here, recall and recognition of words were impaired by a change in the accompanying cues only if the to-be-remembered (TBR) words were of high frequency; low-frequency words did not support the Encoding Specificity Principle. The data suggest that both recall and recognition of a TBR word depend on recognition of a specific interpretation of the word originally encoded, rather than its physical representation.

Anderson, J.R. & Reder, L.M. (1974). Negative judgments in and about semantic memory. Journal of Verbal Learning and Verbal Behavior, 13, 664-681.
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    • This research is concerned with determining how subjects falsify statements like A collie is a cat. A multiple regression analysis was performed which used 22 variables to try to predict the negative judgement times. The predictive variables are time to generate the superordinate of the instance (for example, dog), time to falsify that the superordinate is the predicate (for example, A dog is a cat), and time to encode the instance. This finding and others indicate that a prominent negation strategy is one in which the subject generates the superset of an instance and falsifies that the superset is the predicate. Auxillary regression analysis are also reported for other reaction time measures gathered in the experiments. It is argued that large-scale regression experiments are critical to the inferential logic of a semantic memory experiment.