Individual differences in Sternberg’s memory scanning task

This study provides a new perspective on both the cognitive processes actually implemented and the effect of a simple experimental control - the recall constraint - in Sternberg’s memory scanning task. These findings were highlighted by adopting a new approach based on the comparison of qualitative and quantitative results.The analysis of individual processing, on 72 adults, each participating in one of two experimental conditions (with or without sequence recall), highlighted a large variability in quantitative results as well as qualitative procedures. Based on the participants’ retrospective verbalisations, two categories of strategies were identified: (1) the procedures used to memorize the sequence of digits, and (2) the procedures used to compare this sequence with the test digit, which includes strategies for coding the items and processes for searching them in memory. The analysis of the strategies shows that their frequencies of use depend not only on the experimental condition, but also on the participants, the level of task difficulty and the interaction between participants and level of difficulty. This variability questions the accuracy of Sternberg’s mean model. Furthermore, this approach suggests some answers to the old debate concerning the exhaustive search pattern for the yes response. Indeed, our results show three types of strategies that can be identified according to the different models of search suggested in the literature. The “exhaustive” search, that would only be involved in the recall condition and only for some of the participants, the “self-terminating” search and the “immediate” strategy, which can be identified with a model of parallel search with limited resources. Thus our study suggests that the different search models are appropriate but depend on both the specific experimental conditions and participant’s strategy. Our results should help to improve the interpretation of data collected with this paradigm in cognitive and neuroscientific studies of memory.     

Three-year-olds Remember a Novel Event from 20 Months: Evidence for Long-term Memory in Children?

Abstract

Thirty-seven 3-year-old children, who had learned a 9-action event sequence (“making Play-Doh spaghetti”) when they were 20 months old, returned to the lab to determine whether they would be able to verbally and/or behaviourally recall the event after a 12- to 22-month delay. Children originally participated in the event either one or three times and experienced different parts of the event either at three distinct locations (spatial condition) or at a single location (nonspatial condition). Results show very little evidence of long-term memory for the event after one to two years. Returning children did not verbally recall the event, and they did not perform more actions or sequence the event more accurately than controls, with the exception of the older experimental children who had a tendency to sequence the event more accurately than same-aged controls. Although the results indicate that young children's memory for novel events is not very enduring, there were individual differences in children's ability to remember the event. These differences are discussed in terms of potential differences in cognitive abilities and changing knowledge about retrieval strategies or memory.     

The organisation of musical semantic memory: Evidence from false memories for familiar songs

By adapting a well-known paradigm for studying memory for words—the Deese-Roediger-McDermott or DRM paradigm (Deese, 1959, Roediger & McDermott, 1995)—the two experiments reported here explore memory for song titles and song clips. Participants were presented with five song titles (Experiment 1a) or five 30-second song clips (Experiment 1b) for each of nine popular artists (e.g., Robbie Williams). The most popular song identified for each artist in a pilot task was omitted from the sets of titles/clips. Following a distractor task, participants were asked to write down as many of the songs as they could recall. They were also asked to return a week later and complete a second recall task. Participants falsely recalled a significant number of the related but non-presented songs in both experiments and this increased a week later, while correct recall for presented items decreased. The results are discussed in terms of theory for musical memory as well as in the context of providing a novel method for exploring the organisation of musical memory.     

The effect of divided attention on false memory depends on how memory is tested

In three experiments, we investigated the effects of divided attention on false memory, using the Deese/Roediger-McDermott (DRM) paradigm. In Experiments 1 and 2, participants studied six DRM lists with full attention and six in one of two divided-attention conditions (random number generation or digit monitoring). Both divided-attention conditions increased false recall of related words (Experiment 1) but reduced false recognition (Experiment 2). These results were confirmed in Experiment 3, in which the type of secondary task was manipulated within groups. We argue that the increase in false recall with divided attention reflects a change in participants' response criterion, whereas the decrease in false recognition occurs because the secondary tasks prevent participants from generating associates of the words presented at study.     

Attention, rehearsal, and memory for serial order

In three experiments, subjects attended to one of two simultaneous nine-digit sequences, presented binaurally in different voices (one male, one female). Substantial repetition effects (defined as gains in immediate memory performance for previously presented sequences relative to novel ones) were found for two exposure conditions: (a) one that required reproduction of the full sequence on each exposure (Experiment 1), and (b) one that required recall of a different two-digit subsequence on each exposure (Experiment 2). In Experiment 3, the following conditions produced no repetition effects, even though tests had substantial power to detect small effects: 10 consecutive presentations in the unattended voice; 4 prior presentations in a task that required attention to each digit as it was presented (but not to digit order); and 4 prior presentations in a task that required attention to digit order during their presentations. These results, together with those of previous studies, support the conclusion that repetition effects on immediate memory occur only with procedures that encourage covert rehearsal of full-sequence order on each exposure. These findings also limit the generality of others' conclusions that event order is automatically encoded for attended events, and extend previous findings showing unattended exposures to be without effect on recall measures.     

Maintenance rehearsal: the key to the role attention plays in storage and forgetting

Research with the maintenance-rehearsal paradigm, in which word pairs are rehearsed as distractor material during a series of digit recall trials, has previously indicated that low frequency and new word pairs capture attention to a greater degree than high frequency and old word pairs. This impacts delayed recognition of the pairs and interferes with immediate digit recall. The effect on immediate digit recall may provide the missing converging evidence for the role of attention in memory. In the current study, 3 experiments were conducted to further investigate the role of attention capture and novelty in storage and forgetting. In addition to the previously established effects, the novelty of switching rehearsal between 2 pairs was found to impair both digit recall and memory for the first pair. The attentional effects we obtained were dependent upon participant expectation, and forgetting appears to be due to interference with consolidation rather than decay or traditional associative interference. Finally, the attentional effects we observed in associative recognition were primarily reflected in a lowering of the false alarm rate with increases in the strength of the parent pairs. Although dual-process models can accommodate this finding on the assumption that recollection is invoked at test alongside familiarity, we showed that the level of recall in this paradigm is so small that recollection can be ruled out. Accordingly, our results are challenging for the existing models of associative recognition to accommodate.     

Mechanisms underlying corruption of working memory in Parkinson's disease

Working memory (WM) impairments are reported to occur in patients with Parkinson's disease (PD). However, the mechanisms are unclear. Here, we investigate several putative factors that might drive poor performance, by examining the precision of recall, the order in which items are recalled and whether memories are corrupted by random guessing (attentional lapses). We used two separate tasks that examined the quality of WM recall under different loads and retention periods, as well as a traditional digit span test. Firstly, on a simple measure of WM recall, where patients were asked to reproduce the orientation of a centrally presented arrow, overall recall was not significantly impaired. However, there was some evidence for increased guessing (attentional lapses). On a new analogue version of the Corsi-span task, where participants had to reproduce on a touchscreen the exact spatial pattern of presented stimuli in the order and locations in which they appeared, there was a reduction in the precision of spatial WM at higher loads. This deficit was due to misremembering item order. At the highest load, there was reduced recall precision, whereas increased guessing was only observed at intermediate set sizes. Finally, PD patients had impaired backward, but not forward, digit spans. Overall, these results reveal the task- and load-dependent nature of WM deficits in PD. On simple low-load tasks, attentional lapses predominate, whereas at higher loads, in the spatial domain, the corruption of mnemonic information—both order item and precision—emerge as the main driver of impairment.     

The relationship between recognition and cued recall in memory of enacted and nonenacted information

Summary An experiment was conducted to determine whether the processes underlying memory for enacted and nonenacted events are the same or different. The experimental paradigm used was that of recognition failure of recallable information. At study subjects were given verbal commands (e.g., break the match, roll the ball), that they were to remember or enact and remember. At test subjects were first asked to recognize the noun in each command in the absence of the verb and then to recall the noun with the verb present as cue. Half the subjects were given the two tests in the reverse order. The results demonstrate that enactment and nonenactment differ with respect to the degree of dependence/independence between recognition and recall. In the enactment condition recognition and cued recall are completely independent and in the nonenactment condition they are almost completely dependent.     

Effects of repetition on age differences in associative recognition

The study reported here examined the effect of repetition on age differences in associative recognition using a paradigm designed to encourage recollection at test. Young and older adults studied lists of unrelated word pairs presented one, two, four, or eight times. Test lists contained old (intact) pairs, pairs consisting of old words that had been studied with other partners (rearranged lures), and pairs consisting of two unstudied words (new lures). Participants gave old/new responses and then indicated whether their responses were based on details that they could recollect or on familiarity. Older adults exhibited an ironic effect of repetition—an increase in false alarms on rearranged lures with more study opportunities—whereas young adults did not. Older adults also claimed to recall details of the study episode for rearranged lures whose constituent words were presented more frequently, but this was not true for young adults. Although both young and older adults said that they based correct rejections of rearranged lures on memory for details of the study episode, this effect was stronger for young adults. The observed age differences are consistent with older adults having reduced use of recollection in associative recognition tasks.     

A partial matching theory of the mirror effect in immediate probed recognition

A set of experiments on immediate probed recognition of digit triples is reported in which the variables were list length (five, six, seven, or eight triples), the probability that a probe was old (.33, .5, or .67), and whether the digit triples were presented with an auditory component or articulatory suppression. Previous work had suggested that the false alarm (FA) rate in this paradigm was lower when auditory information was available than when it was not; this observation had led to the development of thepartial matching theory of immediate probed recognition, according to which FAs could arise not only as a result of unlucky guesses but also when new probes shared a first digit in common with a partially retained target triple. It was argued that partial memory representations were less likely following auditory presentation than following articulatory suppression. Partial matching theory is contrasted with therational response theory, according to which all FAs are unlucky guesses; partial matching theory gave a better account of the present experimental data than did rational response theory. However, a logical relationship between the two theories was suggested, a consequence of which was that rational response theory could be modified to include partial matching in such a way as to account for mirror effects, not only in unusually difficult immediate probed recognition tasks, but also in the more commonly studied mixed test list paradigm involving words of high or low frequency.     

Poor working memory predicts false memories

Two studies investigated whether individual differences in simple span verbal working memory and complex working memory capacity are related to memory accuracy and susceptibility to false memory development. In Study 1, undergraduate students (N=60) were given two simple span working memory tests: forward and backward digit span. They also underwent a memory task that is known to elicit false memories of nonpresented words, the Deese/Roediger-McDermott (DRM) paradigm. Poor simple span working memory (as reflected by suboptimal backward digit span scores) was related to elevated levels of false recognition. Study 2 (N=65) replicated this finding, in that suboptimal backward digit span performance was found to be predictive of false recognition. However, complex working memory capacity (operation span) was not related to false recognition. This pattern suggests that even in a homogenous sample of undergraduates, poor working memory is associated with the susceptibility to recollect words never presented.     

Prime time news: The influence of primed positive and negative emotion on susceptibility to false memories

We examined the relation between emotion and susceptibility to misinformation using a novel paradigm, the ambiguous stimuli affective priming (ASAP) paradigm. Participants (N = 88) viewed ambiguous neutral images primed either at encoding or retrieval to be interpreted as either highly positive or negative (or neutral/not primed). After viewing the images, they either were asked misleading or non-leading questions. Following a delay, memory accuracy for the original images was assessed. Results indicated that any emotional priming at encoding led to a higher susceptibility to misinformation relative to priming at recall. In particular, inducing a negative interpretation of the image at encoding led to an increased susceptibility of false memories for major misinformation (an entire object not actually present in the scene). In contrast, this pattern was reversed when priming was used at recall; a negative reinterpretation of the image decreased memory distortion relative to unprimed images. These findings suggest that, with precise experimental control, the experience of emotion at event encoding, in particular, is implicated in false memory susceptibility.     

Skilled memory in expert figure skaters

The present studies extend skilled-memory theory to a domain involving the performance of motor sequences. Skilled figure skaters were better able than their less skilled counterparts to perform short skating sequences that were choreographed, rather than randomly constructed. Expert skaters encoded sequences for performance very differently from the way in which they encoded sequences that were verbally presented for verbal recall. Tasks interpolated between sequence and recall showed no significant influence on recall accuracy, implicating long-term memory in skating memory. There was little evidence for the use of retrieval structures when skaters learned the brief sequences used throughout these studies. Finally, expert skaters were able to judge the similarity of two skating elements faster than less skilled skaters, indicating a faster access to semantic memory for experts. The data indicate that skaters show many of the same skilled-memory characteristics as have been described in other skill domains involving memorization, such as digit span and memory for dinner orders.     

Eliciting and comparing false and recovered memories: an experimental approach

We describe an experimental paradigm designed to elicit both recovered and false memories in the laboratory. All participants saw, on a video screen, three critical categorized lists of words mixed in randomly with eighteen filler categorized lists. Those in the blocking condition then had several paper‐and‐pencil tasks that involved only the 18 non‐critical filler lists. An uncued recall test was then given, asking participants to recall all the lists they originally saw on the video screen. Finally, there was a cued recall test that provided category cues for the three critical lists. Substantial memory blocking of critical lists on the uncued test and recovery on the cued recall test was observed in all three experiments. In Experiments 2 and 3, many false and recovered memories were elicited on the cued recall test by including cues for the three critical (forgotten) lists, plus cues for three lists that had never been presented. False memories were distinguishable from truly recovered memories in cued recall by ‘know’ versus ‘remember’ judgements, and by confidence ratings; accurately recovered memories were associated with higher confidence. False and recovered memories could not be discriminated based on recall latency. The results repeatedly show powerful effects of memory blocking and recovery. We also show that recovered and false memories can be elicited within a single experimental procedure, and there may be unique characteristics of each. Although we urge caution in generalizing to false and recovered memories of trauma, we suggest that variations of our comparative memory paradigm may be useful for learning about such phenomena. Copyright © 2003 John Wiley & Sons, Ltd.     

Midazolam amnesia and short-term/working memory processes

We examined whether midazolam impairs short-term/working memory processes. We hypothesize that prior dissociations in midazolam's effects on short-term/working memory tasks and episodic memory tasks arise because midazolam has a larger effect on episodic memory processes than on short-term/working memory processes. To examine these issues, .03 mg/kg of participant's bodyweight of midazolam was administered in a double-blind placebo-controlled within-participant design. Performance on the digit span and category generation/recall tasks was examined. The results of Experiment 1 demonstrated that: (1) midazolam impaired performance on the digit span task; (2) midazolam did not impair performance on the category generation task; (3) midazolam impaired performance on the category recall task; and (4) midazolam's effect on category recall was four times as large as its effect on digit span. The results of Experiment 2 demonstrated that midazolam did not impair digit span performance when the digit span task was administered at a later time. These results suggest that midazolam can impair short-term/working memory processes, but these effects are substantially smaller than midazolam's effect on episodic memory processes. Moreover, they demonstrate that conscious awareness of materials during study is not sufficient to produce episodic memory.     

Monitoring the future: object and source memory for real and imagined events

In these experiments a memory‐monitoring decision is made, whereby subjects must decide not only whether or not to‐be‐learned stimuli will be remembered—the focus of all of the past research into the Judgement of Learning (JOL)—but also whether they will be able to assess the source of those stimuli, as assessed by a new measure, Judgement of Source (JOS). In Experiment 1 subjects had to judge whether they would remember the occurrence and the source of items that were either seen or imagined. Although seen items were better remembered and sourced than imagined, subjects were unable to predict this outcome: they underestimated their ability to recall seen items and overestimated their ability to recall imagined items. In Experiment 2 subjects had to discriminate between self‐performed or other‐performed enacted or imagined events. We expected that the motor cues associated with overt performance should provide more sensory information than had the visual input in Experiment 1, and this should help subjects to discriminate between real and imagined items. As predicted, JOL magnitude showed that subjects were now able to predict accurately that they would recall more enacted events than imagined events. JOS magnitude showed that subjects incorrectly predicted that self‐enactment would assist source memory compared to imagination. However, it was the source of other‐focused events which was more accurately remembered. The results are discussed in terms of Koriat's (1997) view about cue utility in making JOLs. Copyright © 1999 John Wiley & Sons, Ltd.     

The influences of partner accuracy and partner memory ability on social false memories

In this study, we examined whether increasing the proportion of false information suggested by a confederate would influence the magnitude of socially introduced false memories in the social contagion paradigm Roediger, Meade, & Bergman (Psychonomic Bulletin & Review 8:365–371, 2001). One participant and one confederate collaboratively recalled items from previously studied household scenes. During collaboration, the confederate interjected 0 %, 33 %, 66 %, or 100 % false items. On subsequent individual-recall tests across three experiments, participants were just as likely to incorporate misleading suggestions from a partner who was mostly accurate (33 % incorrect) as they were from a partner who was not at all accurate (100 % incorrect). Even when participants witnessed firsthand that their partner had a very poor memory on a related memory task, they were still as likely to incorporate the confederate’s entirely misleading suggestions on subsequent recall and recognition tests (Exp. 2). Only when participants witnessed firsthand that their partner had a very poor memory on a practice test of the experimental task itself were they able to reduce false memory, and this reduction occurred selectively on a subsequent individual recognition test (Exp. 3). These data demonstrate that participants do not always consider their partners’ memory ability when working on collaborative memory tasks.     

Item strength affects working memory capacity

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 3 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 also on their strength or familiarity.