Immediate memory for faces: Long- or short-term memory?

Immediate recognition memory span and short-term forgetting for non-verbal stimuli (“unfamiliar faces”) were investigated in normal subjects and amnesic patients. Surnames were used as a verbal control. It was found that normal subjects had a reliable immediate recognition span of one for faces and that there was no decrement in performance in the retention of three faces over a 30-s interval. Amnesic subjects were impaired on both the immediate memory span task and on the short-term forgetting task. This pattern of results contrasts with those obtained using surnames on which the results were comparable to other verbal S.T.M. tasks. It is suggested that performance on these tasks of recognition memory for faces is determined by L.T.M. processes. The implications for the interpretation of S.T.M. are discussed.     

Semantic memory: Complexity or connectivity?

The complexity hypothesis predicts that concept-feature verification times should be directly related to the number of features associated with a concept (the fan effect). Conversely, the connectivity hypothesis predicts that for interconnected semantic relationships, this verification time should be inversely related to the number of closely associated features (the reversed fan effect). In the present experiments, although the time required for episodic recognition memory decisions tended to be directly related to the number of features associated with a concept, semantic verification times were inversely related to the complexity of the concept. In addition, the concept's complexity was at least as good a predictor of performance in semantic tasks as was the strength of association between the concept and feature. Both of these results are interpreted in terms of the connectivity hypothesis.     

The co-witness misinformation effect: memory blends or memory compliance?

For 30 years hundreds of researchers have shown participants videos and slide-sequences of events, presented the participants with misleading information, and found that this misinformation distorted their memories. The purpose of this study was to establish whether those misled participants are reporting a memory blend of the two sources of information or whether they are simply complying with the post-event information. A total of 92 participants were shown one of two versions of six different videos, which included some subtle differences. After having watched each video individually, participants were paired with someone who had seen the other version and they discussed the clips together. They then individually answered questions about the videos, and their responses showed that some of the distorted memories were blends of the original information and the post-event information. The implications of these findings are discussed.     

Time window from visual images to visual short-term memory: consolidation or integration?

When two dot arrays are briefly presented, separated by a short interval of time, visual short-term memory of the first array is disrupted if the interval between arrays is shorter than 1300-1500 ms (Brockmole, Wang, & Irwin, 2002). Here we investigated whether such a time window was triggered by the necessity to integrate arrays. Using a probe task we removed the need for integration but retained the requirement to represent the images. We found that a long time window was needed for performance to reach asymptote even when integration across images was not required. Furthermore, such window was lengthened if subjects had to remember the locations of the second array, but not if they only conducted a visual search among it. We suggest that a temporal window is required for consolidation of the first array, which is vulnerable to disruption by subsequent images that also need to be memorized.     

Switching between memory and perception: Moving attention or memory retrieval?

Weber, Burt, and Noll (1986) estimated that the time needed to switch attention between memory and perception was around 300 msec. The first two experiments in the present paper estimated switching time using a variation of their task. Subjects reported aloud lists of six items. The items were read off a computer screen (perception), recited from memory, or reported alternately from the two sources. The data show that the switching-time estimate is influenced by input/output compatibility, response-initiation times, and memory load. When these factors were controlled, estimated switching time dropped to around 100-150 msec. The data suggest, however, that the switch from perception to memory might be slower than the switch from memory to perception, which would invalidate the formula used to compute switching time. Experiment 3 tested the time for a single switch from perception to memory and a single switch from memory to perception by restricting report to one pair of items in the list. When the to-be-reported pair was precued, estimated switching time dropped to zero. When the pair was not precued, the memory-to-perception switching time remained at zero, but the perception-to-memory time was more than 400 msec. The pattern of results forced a reconceptualization of the task in terms of memory retrieval rather than attention switching. The attention-switching times appear to reflect processes required to select items from memory.     

The unattended speech effect: perception or memory?

Broadbent (1983) has suggested that the influence of unattended speech on immediate serial recall is a perceptual phenomenon rather than a memory phenomenon. In order to test this, subjects were required to classify visually presented pairs of consonants on the basis of either case or rhyme. They were tested both in silence and against a background of continuous spoken Arabic presented at 75 dB(A). No effect of unattended speech was observed on either the speed or accuracy of processing. A further study required subjects to decide whether visually presented nonwords were homophonous with real words. Again, performance was not impaired by unattended speech, although a clear effect was observed on an immediate serial memory task. Our results give no support to the perceptual interpretation of the unattended speech effect.     

Episodic memory reconsolidation: Updating or source confusion?

Reactivation of apparently stable, long-term memory can render it fragile, and dependent on a re-stabilisation process referred to as “reconsolidation”. Recently we provided the first demonstration of reconsolidation effects in human episodic memory (Hupbach, Gomez, Hardt, & Nadel, 2007 Hupbach, A., Gomez, R., Hardt, O. and Nadel, L. 2007. Reconsolidation of episodic memories: A subtle reminder triggers integration of new information. Learning & Memory, 14: 47–53. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hupbach, Hardt, Gomez, & Nadel, 2008 Hupbach, A., Hardt, O., Gomez, R. and Nadel, L. 2008. The dynamics of memory context-dependent updating. Learning & Memory, 15: 574–579.  [Google Scholar]). Memory for a set of objects was modified by the presentation of a new set, if and only if participants were reminded of the first learning episode before learning the new set. The present study asks whether this effect can be interpreted as a source discrimination problem; i.e., participants have difficulties remembering which objects were presented during which session, and do not actually incorporate new objects into the reactivated memory. The present study used a recognition test and asked participants directly about the source of their memories. Participants in the no-reminder group showed very few source errors. Participants in the reminder group misattributed the source of objects from the second set as being from the first set but not vice versa, thus demonstrating updating of the original memory. This finding is informative with respect to the misinformation paradigm, and reconsolidation is discussed as a possible mechanism underlying our results and the misinformation effect.     

Underestimating the duration of future events: memory incorrectly used or memory bias?

People frequently underestimate how long it will take them to complete a task. The prevailing view is that during the prediction process, people incorrectly use their memories of how long similar tasks have taken in the past because they take an overly optimistic outlook. A variety of evidence is reviewed in this article that points to a different, although not mutually exclusive, explanation: People base predictions of future duration on their memories of how long past events have taken, but these memories are systematic underestimates of past duration. People appear to underestimate future event duration because they underestimate past event duration.     

Who benefits from memory training?

Cognitive training programs can have significant benefits. However, their efficacy is often reduced for individuals of advanced age or lower cognitive ability. Using older adult subjects, we examined the role of self-initiation of cognitive control in a training program that targets recollection memory. Relative time spent on an open-ended, intentional encoding task that requires the self-initiation of cognitive control was highly predictive of improvement in the training task, and fully accounted for individual differences related to age and crystallized intelligence. Analyzing training programs from the perspective of cognitive theory may help clarify how these programs have their effects and suggest ways to optimize such programs for the individuals who need them most.     

Short-term memory capacity: magic number or magic spell?

Previous experiments have found that memory span is greater for items that can be pronounced more quickly. For a variety of materials the span equals the number of items that can be pronounced in about 1.5 s, presumably the duration of the verbal trace. This suggests a model for immediate recall: The probability of correctly recalling a list equals the probability that the time to recite the list is less than the variable duration of the trace. Recall probability for lists of various lengths was determined for six materials. Later, subjects read the lists aloud. The standard normal deviates corresponding to probability of correct recall were linear in pronunciation time. Evidently, over subjects, a normal distribution is a reasonable approximation of the distribution of the trace duration. The mean and variance of the trace duration were estimated. The mean (1.88 s) agrees well with previous estimates, and the model accounts for 95% of the variance in immediate recall.     

Behavioral contrast in short term memory: Serial binary memory models or parallel continuous memory models?

This paper develops a model wherein STM primacy as well as recency effects can occur. The STM primacy effects can be used to generate correct immediate recall of short lists that have not been coded in LTM. The properties of the model are interpreted in terms of explicit neural mechanisms. The STM primacy effect is a behavioral contrast effect that is analogous to the behavioral contrast that can occur during discrimination learning. The adaptational mechanism that accounts for these effects is also implicated in data on reaction time, retinal adaptation, ratio scales in choice behavior, and von Restorff-type effects. Its ubiquitous appearance is due to the fact that it solves a universal problem concerning the parallel processing of patterned data by noisy cells with finitely many excitable sites. It is argued that the STM primacy effect is not measured in interference experiments because it is masked by competitive STM interactions. These competitive interactions do not prevent the LTM primacy effect from influencing performance. The paper criticizes recent models of STM that use computer analogies to justify binary codes, serial STM buffers, and serial scanning procedures. Several deficiencies of serial models in dealing with psychological and neural processing are overcome by a model in which continuous STM activities and parallel real-time operations play an important role.     

Mood-congruent memory in depression: emotional priming or elaboration?

We investigated whether mood-congruent memory (MCM) bias in depression is a function of implicit or explicit memory. Implicit memory is taken as a measure of ease of activation, whereas explicit memory also taps elaboration. As expected, MCM bias was found in the explicit memory task but not in the implicit memory task. We believe this finding supports the involvement of elaborative mechanisms in MCM. In addition, memory bias was found with words related to depression but not with words denoting physical threat. Thus, the MCM bias in explicit memory was found to be specific to information that was congruent with depression rather than to all negative information.     

Protecting and respecting the vulnerable: existing regulations or further protections?

Scholars and policymakers continue to struggle over the meaning of the word “vulnerable” in the context of research ethics. One major reason for the stymied discussions regarding vulnerable populations is that there is no clear distinction between accounts of research vulnerabilities that exist for certain populations and discussions of research vulnerabilities that require special regulations in the context of research ethics policies. I suggest an analytic process by which to ascertain whether particular vulnerable populations should be contenders for additional regulatory protections. I apply this process to two vulnerable populations: the cognitively vulnerable and the economically vulnerable. I conclude that a subset of the cognitively vulnerable require extra protections while the economically vulnerable should be protected by implementing existing regulations more appropriately and rigorously. Unless or until the informed consent process is more adequately implemented and the distributive justice requirement of the Belmont Report is emphasized and operationalized, the economically disadvantaged will remain particularly vulnerable to the harm of exploitation in research.     

Positional information in short-term memory: Relative or absolute?

Evidence suggests that short-term memory for serial order includes information about the positions of items in a sequence. This information is necessary to explain why substitution errors between sequences tend to maintain their position within a sequence. Previous demonstrations of such errors, however, have always used sequences of equal length. With sequences of different length, both transpositions between groups (Experiment 1) and intrusions between trials (Experiment 2) are shown to respect position relative to the end as well as to the start of a sequence. These results support models in which position is coded by start and end markers, but not models in which position is coded in temporal or absolute terms. Possible interpretations of an end marker are discussed.     

Retrieval‐induced forgetting of autobiographical memory details

Several studies suggest that intrusive and overgeneral autobiographical memory are correlated. Thus, paradoxically, in some patients a hyperaccessibility of memory for one (series of) event(s) goes hand‐in‐hand with a scarcity of memories for other personal experiences. This clinical observation is reminiscent of the laboratory phenomenon of retrieval‐induced forgetting (RIF). This refers to the finding that repeatedly recalling some experimental stimuli impairs subsequent recall of related (i.e., tied to the same retrieval cue) stimuli. RIF of emotional autobiographical memories might provide an experimental model for the clinical memory phenomena in question. The present paper reports two experiments that explored the merits of applying the retrieval practice paradigm to relatively broad categories of autobiographical memories. Both studies found a significant RIF effect in that practised memories were recalled better than unrelated unpractised (baseline) memories. In addition, unpractised memories that were related to the practised memories were recalled more poorly than baseline memories. Implications of these findings for modelling the co‐occurrence of intrusive and overgeneral memories are discussed.     

Yours or mine? Ownership and memory

An important function of the self is to identify external objects that are potentially personally relevant. We suggest that such objects may be identified through mere ownership. Extant research suggests that encoding information in a self-relevant context enhances memory (the so-called 'self-reference effect'), thus an experiment was designed to test the impact of ownership on memory performance. Participants either moved or observed the movement of picture cards into two baskets; one of which belonged to self and one which belonged to another participant. A subsequent recognition test revealed that there was a significant memory advantage for objects that were owned by self. Acting on items (i.e., moving them) had no impact on memory. Results are discussed with reference to the importance of self-object associations in cognition.