Memory for traumatic events

This research compares memory for traumatic events with memory for non-traumatic versions of the same event. In Experiment 1, subjects watched an event depicted in slides while focusing and rehearsing the central detail of each slide. They were tested after a short or a longer retention interval (20 min or 2 weeks). Subjects who watched the traumatic version were better able to recall the central details that they had rehearsed, but were less well able to recognize the specific slides that they saw. Better recall for the traumatic group did not occur because the words used to describe the recalled details were inherently more memorable, as shown in Experiment 2. In Experiment 3, subjects watched either a traumatic or non-traumatic version of a filmed event and about 6 months later they were asked to remember the essence of the film. Subjects who saw the traumatic version were better able to recall the essence of the film. A similar finding was obtained with a group of subjects from Experiment 1 who were also contacted about 6 months after their initial participation. These results suggest that some information (the essence, the theme) of a traumatic event might be relatively well retained in memory, while memory is impaired for many of the specific, and especially peripheral, details.     

Remembering computer command names: Effects of subject generation versus experimenter imposition

Two experiments analyzed the effectiveness of goal statements in aiding recall of self-generated as opposed to experimenter-imposed command names. Subjects were presented with a series of before-after pairs representing the computer states before and after a command was executed. In Experiment 1, during study, one group of subjects generated a command name in response to each pair; a second group generated a goal statement describing the goal to be accomplished in addition to generating a command name. During recall, half of each group was required to recall the name, whereas the other half was required to describe the goal before attempting to recall the name. In Experiment 2, during study, command names (and goals for those subjects in the goal condition) were imposed by the experimenter rather than generated by the subject. Subjects who generated goals and names recalled more command names than did those who generated only names or who received imposed goals and/or names. Generation of an appropriate goal at study improved encoding by helping subjects to select more appropriate command names; generation of an appropriate goal at test improved retrieval for appropriate names only, presumably by activating a relevant subset of names. Even in the relatively simple task of naming and remembering command names, having an appropriate model of the domain through the use of specific goal statements substantially improved performance.     

Hypnosis and pseudomemories: the effects of prehypnotic expectancies

Contrary to predictions, the pseudomemory rate of subjects who received prehypnotic information that hypnosis increased recall was indistinguishable from the pseudomemory rates of subjects who received information that hypnosis did not increase recall and of subjects who received no specific prehypnotic information. Indeed, by the last recall trial, none of the 47 subjects exhibited pseudomemory. Subjects exhibited faulty memory of events that actually occurred (i.e., pencils spilling), and were as uncertain of events that actually occurred, as they were of suggested events that did not occur during the session (telephone ringing). Subjects were generally consistent in their certainty, or lack of it, across events. Finally, subjects led to believe that hypnosis is an altered state of consciousness were less aware of external events, and had the lowest rate of recall of target suggestions compared with subjects in the comparison groups.     

Metamemory for narrative text

In this experiment, we investigated metamemory for narrative text passages. Subjects read two stories and made memory predictions for the idea units in one and rated the importance of ideas in the other. Half of the subjects were asked to recall the story immediately after reading the passages and half were asked to recall 1 week later; half received passages with single inconsistent idea units and half received passages with corresponding consistent idea units. All subjects made confidence judgments about the accuracy of their recall. Subjects’ prediction ratings were related to recall, as shown by significant prediction accuracy quotients. Importance ratings were related to recall on the delayed test but not on the immediate test. Memory prediction ratings predicted recall better than did importance ratings. The absolute level of memory predictions did not differ with delay, but subjects did give higher confidence judgments on an immediate than on a delayed test. Subjects recalled the inconsistent idea better than the consistent idea for one story but not for the other. For both stories, subjects predicted that they would remember the inconsistent ideas better, suggesting that they have avon Restorff-type view, rather than a schema view, of memory. We conclude that subjects can predict their memory for the idea units in narrative text.     

Utilization of base-rate information during feeling-of-knowing judgments.

We examined whether subjects use base-rate information about item difficulty when making feeling-of-knowing judgments for items they failed to recall. First, the subjects attempted to recall the answers to general-information questions. Then, for those items they recalled incorrectly, half of the subjects received information about the normative probability of recall of each item while judging their feeling of knowing. The other subjects made their feeling-of-knowing judgments without receiving any base-rate information. Finally, all subjects had a forced-choice recognition test on those items to validate the accuracy of their feeling-of-knowing judgments. Relative to the no-base-rate information group, the base-rate group had lower feelings of knowing for normatively difficult items and higher feelings of knowing for normatively easier items. Subjects who had received base-rate information during the judgment state had greater feeling-of-knowing accuracy than subjects who did not receive base-rate information. However, even the predictions from subjects who received base-rate information were not significantly more accurate for predicting subsequent recognition than were the predictions derived from normative information alone.     

Relationships between metamemory, memory predictions, and memory task performance in adults

A cross-sectional sample of adults recalled categorized word lists and narrative texts. Subjects gave performance predictions before each of 3 recall trials for each task. Older subjects had poorer memory performance and also predicted lower performance levels than did younger subjects. The LISREL models suggested (a) direct effects of memory self-efficacy (MSE) on initial predictions; (b) upgrading of prediction-performance correlations across trials, determined by direct effects of performance on subsequent predictions; (c) significant effects of a higher order verbal memory factor on MSE; and (d) an independent relationship of text recall ability to initial text recall performance predictions. These results lend support to the theoretical treatment of predictions as task-specific MSE judgments.     

When are social judgments made? Evidence for the spontaneousness of trait inferences

Do people make trait inferences, even without intentions or instructions, at the encoding stage of processing behavioral information? Tulving's encoding specificity paradigm (Tulving & Thomson, 1973) was adapted for two recall experiments. Under memory instructions only, subjects read sentences describing people performing actions that implied traits. Later, subjects recalled each sentence under one of three cuing conditions: (a) a dispositional cue (e.g., generous), (b) a strong, nondispositional semantic associate to an important sentence word; or (c) no cue. Recall was best when cued by the disposition words. Subjects were unaware of having made trait inferences. Interpreted in terms of encoding specificity, these results indicate that subjects unintentionally made trait inferences at encoding. This suggests that attributions may be made spontaneously, as part of the routine comprehension of social events.     

The Relative Importance of Anticipated Test Format and Anticipated Test Difficulty on Performance

In this investigation, the relative importance of the effects of anticipated test format and anticipated test difficulty on performance was examined by simultaneously manipulating both. Experiments 1 and 2 showed that test performance was affected more by anticipated test format than by anticipated test difficulty. This suggests that the superior performance of subjects who had anticipated a recall test versus those who had anticipated a recognition test, reported here and in previous studies, is more likely to be due to anticipating a recall format than to anticipating a more difficult test. Experiment 2 showed that subjects who had anticipated a recall test studied longer than subjects who had anticipated a recognition test, even when recall tests were less difficult than recognition tests. One explanation for this finding is that subjects inaccurately monitor the relative difficulty of tests across test formats. Subjects rated recall items as more difficult than recognition items, even when recall items are actually less difficult (Experiment 3). These findings suggest that a priori metacognitive knowledge may reduce the accuracy of on-line metacognitive monitoring.     

Improving retrieval

The present research investigated whether ability for retrieval might be improved by practice at retrieval. Retrieval practice trials, each of 10 min duration, required subjects to attempt to recall as many examples as possible of a designated category. Two kinds of practice were investigated. Subjects given general practice attempted to recall a different category on each successive practice trial. Subjects given specific practice attempted to recall the same category on each successive practice trial. General practice had a negligible effect on recall, even when subjects practised daily for over a month. In contrast, specific practice substantially improved recall, facilitating retrieval of 50 to 100 per cent of all the example subjects known for a category.     

Test anxiety and breadth of encoding experiences in free recall

Subjects made three ratings for each of 30 words, then had an unannounced immediate free recall test and a second test after 1 week. There was no evidence to indicate significantly better retention on either test when the dimensions rated were unrelated as opposed to related. Subjects low on test anxiety performed better overall than subjects who scored high on either the emotionality or worry components of test anxiety. On the delayed test, the test anxiety effect was apparent only when study ratings involved unrelated dimensions (i.e., broad encoding). This interaction is consistent with two conclusions. First, rating related dimensions led to narrow encodings, thus hindering low-anxiety subjects who normally encode broadly. Second, even explicit ratings of unrelated dimensions did not induce high-anxiety subjects to encode more broadly. That the high-anxiety deficit was not overcome even with explicit orienting tasks may indicate inflexibility in deploying memory strategies.     

Topographically distinct cortical activation in episodic long-term memory: The retrieval of spatial versus verbal information

Two experiments are reported to study slow potentials in the EEG during reactivation of spatial and verbal information. Subjects had to learn associations between drawings and one, two, or three mediators (locations in Experiment 1, nouns in Experiment 2). During recall, subjects had to decide whether or not two drawings were linked to each other by a common mediator. EEG was recorded during learning and recall. Both experiments were completely equivalent. Irrespective of the quality of the mediators, response time proved to be a linear function of the numbers of mediators to be recalled. Negative slow potentials that accompanied the reactivation of information during anticipation learning and cued recall had a material-specific topography: The maximum was found over the parietal cortex for spatial information and over the left frontal cortex for verbal information. Moreover, the amplitude at these scalp locations varied with the amount of the to-be-retrieved information. The results support the claim of topographically distinct cell assemblies specialized for storage and retrieval of distinct kinds of information.     

Understanding text after severe closed-head injury: assessing inferences and memory operations with a think-aloud procedure

A think-aloud method was used to examine the content of information available to working memory during narrative comprehension in a CHI population. Twenty severe CHI participants (>1 year post-injury) and 20 controls talked aloud after they read each sentence of story narratives. Trabasso and Magliano's (1996a) verbal protocol analysis was then used to code for the production of inferential and non-inferential clauses and the memory operations that supported inferential clause production. We found that CHI and control groups produced a comparable number of clauses, that inferences dominated narrative comprehension, and that both groups produced more explanatory inferences than predictive or associative inferences. Despite these qualitative similarities, the CHI group demonstrated poorer comprehension, generated proportionately fewer inferences, relied less on retrieval as a memory source for explanatory inferences, and produced more non-inferential clauses and associative inferences.     

Very Long-term Recall in Infants: Infantile Amnesia Reconsidered

Abstract

Subjects who had participated in a study on non-verbal recall before their first birthday returned to the laboratory one year later and were tested for recall of their previous visit. During their previous visit they had shown recall of both familiar and novel actions on a set of novel objects. However, after a year's delay, evidence for recall was found for the familiar actions only. One action in particular was responsible for this finding: feeding a teddy bear with a schematic bottle. The majority of the returning subjects who had been shown this action repeated it after a year, whereas none of the other returning subjects and few of the subjects in the control groups performed this action. The results indicate that young infants have the ability to recall an event both at 11 months of age and after a delay as long as one year. The finding that infants can recall during a period that later becomes inaccessible to memory is important to our understanding of infantile amnesia.     

The accuracy of beliefs about retrieval cues

We investigated the accuracy of predictions about semantic, environmental, and phonological cues for remembering. Subjects rated the pleasantness of 10 words in each of four rooms, predicted the number of words that they would recall with and without one of the three types of cues, and then were tested for free or cued recall. Consistent with their predictions, subjects who received semantic cues recalled more words than did subjects in the free-recall group. The subjects in the other cuing conditions did not benefit from the cues; furthermore, they overestimated the value of phonological cues, and they believed that environmental cues were ineffective. Finally, confidence ratings for cued-recall predictions did not reflect the pattern of cued-recall performance. Subjects were least confident about their predictions for semantic cuing and most confident about their predictions for recall to be cued phonologically.     

Lateralized impairment of the emotional enhancement of verbal memory in patients with amygdala-hippocampus lesion

This study investigated amygdala-hippocampus's functional asymmetry in the emotional modulation of memory for stories. Thirty-nine, right-handed, drug-resistant epilepsy patients who had been submitted to unilateral temporal lobectomy (19 left and 20 right) watched either an arousing or neutral version of a story presented audio-visually. The slide sequence was the same in the neutral and arousing version, the narratives were matched for structure and comprehensibility. The set and order of the 11 slide sequence were identical in both conditions. Free recall and recognition measures were taken 2h after story presentation. Subjects in the TLE group who watched the arousing version recalled more details than the subjects who watched the neutral version (t(37)=3.4,p<.001). The group who watched the arousing version recalled more details of the phase 2 of the story (t(37)=6.76,p<.001). Scores in both conditions did not differ between control subjects and temporal lobectomy patients. When the right and left lesioned groups' results were analyzed separately, it was observed that the two groups did not differ in their recall of the neutral version. The right lesioned group recalled more items of the arousal than the neutral version (Z=-3.55,p<.001). However the left lesioned group did not show the memory enhancement for the emotional version, in this group it was only found an enhanced recall of the more pictorial emotional segment of the narrative (Z=-3.11,p<.001). This illustrates that the right amygdala can influence retention of complex emotional stimuli with verbal and pictorial arousing properties. We concluded that an intact left amygdala-hippocampus is important for enhancement of memory related to emotionally arousing verbal material.     

Inadequacy of recall as a basis for frequency knowledge.

Subjects studied a word list comprising varying numbers of words from distinct semantic categories. The category names (trees, colors, etc.) were then re-presented, and for each name subjects either recalled as many exemplars as they could or estimated how many had been included in the list (Experiments 1 and 2). Recall was not sufficiently informative about actual category sizes to account for performance in the frequency estimation task. Moreover, it remained insufficiently informative when efforts were made to induce a recall-estimate strategy by requiring overt recall prior to estimation (Experiments 3-5), by using very small categories (Experiment 4), and by not showing the category name at study (Experiment 5), even though it did allow a partial account of estimation when the category exemplars were individually cued (Experiment 6). It is concluded that the role of recall in frequency estimation is much exaggerated.     

Developmental differences in schema dependency for temporally ordered story events

This research project was undertaken to investigate whether temporally ordered story events would be recalled in logical sequence as opposed to presentation order by various ages and under various task conditions. A 24-hour delayed condition was used as well as immediate recall. Six-year-olds, 8-year-olds, and adults were asked to recall four narratives. Instructions given were either vague or specifically required subjects to recall events exactly as they had been presented. Following the delayed recall, a picture-sequencing task was adminstered to assess whether picture cues would enable subjects to demonstrate awareness of input order even though they had reordered events in recall. All subjects reordered more during the delayed recall than during the immediate recall. Age differences (p<0003) occurred in the ability of subjects to demonstrate verbatim memory on the picture-sequencing task. Findings suggest that in contrast to adults, once children have reordered narrative events in memory, they no longer have an alternative verbatim version available. Results also suggest a greater schema dependency in children than in adults in recall tasks.     

Possible learned detection of exogenous brain frequency electromagnetic fields: a case study

Zener card representations were presented visually for 15 sec. every 30 sec. for a total of 40 trials per session over 17 sessions to a single subject who displayed temporal lobe lability. During the 15 sec. before the presentation of one of the symbols (target) either a specific 4-Hz magnetic field pattern or a 1-Hz or 7-Hz magnetic field was presented bilaterally at the level of the temporal lobes. Field strengths were in the order of milligauss (about 1000X background values). The subject was required to anticipate the next symbol for each trial. Only when the 4-Hz field preceded the target symbol did the subject's accuracy of guessing remain systematically above (50%) chance (20%) over the sessions. These results suggest that exogenous magnetic fields may become discriminative stimuli through temporal association. Evidence of habituation was also obtained.     

Schema anticipation in recall: memory process or report strategy?

Summary This article reports an experimental investigation testing the hypothesis that recall reports are systematically biased by the recaller's knowledge about who is to receive the recall report, while that bias is absent from a recognition test. Subjects listened to one of two versions of a story recounting John's visit to the doctor. After the story was read, subjects were asked to recall the story either with standard-recall instructions or with instructions to recall for peers, for Martians, or for a contest. In a fifth condition, subjects performed a filler activity, viz., the recall of a personal experience. After the recall test subjects were administered a recognition test. Between the groups no systematic differences in memory performance were observed in the recognition test. Recall for peers appeared to be poorer than recall in the other conditions. Subjects in the recall for a contest condition scored higher than the subjects in the other groups. Not only did groups differ with respect to bias, but there were also systematic differences in the memory or discrimination scores. The findings are discussed within the framework of schema theory.