Does jury deliberation really improve jurors' memories?

The courts assume that jury deliberation corrects errors in jurors' memories, so that the verdict is based on accurate memory for the trial. We evaluated the validity of this assumption by examining jurors' memories and verdicts both before and after deliberation. Unlike previous studies, we tracked how event memories changed as a function of how they were discussed in deliberation. Overall, deliberation resulted in only a slight memory improvement. Deliberation corrected errors and did not introduce distortions. Reasons for such slight memory improvement are that jurors did not think they had memory gaps and thus did not use the deliberation process to improve their memory, and jurors who controlled deliberation were not always the most accurate in their memories. Finally, those most likely to change their verdict as a result of deliberation were not those who had the least accurate memories, but rather those who had the least confidence in their memories. Copyright © 2002 John Wiley & Sons, Ltd.     

The time course of spatial memory distortions

Four experiments investigated the memory distortions for the location of a dot in relation to two horizontally aligned landmarks. In Experiment 1, participants reproduced from memory a dot location with respect to the two landmarks. Their performance showed a systematic pattern of distortion that was consistent across individual participants. The three subsequent experiments investigated the time course of spatial memory distortions. Using a visual discrimination task, we were able to map the emergence of spatial distortions within the first 800 msec of the retention interval. After retention intervals as brief as 50 msec, a distortion was already present. In all but one experiment, the distortion increased with longer retention intervals. This early onset of spatial memory distortions might reflect the almost immediate decay of detailed spatial information and the early influence of an enduring spatial memory representation, which encodes spatial information in terms of the perceived structure of space.     

Why misinformation is more likely to be recognised over time: A source monitoring account

Although memory for actual events tends to be forgotten over time, memory for misinformation tends to be retrieved at a stable rate over long delays or at a rate greater than that found immediately after encoding. To examine whether source monitoring errors contribute to this phenomenon, two experiments investigated subjects' memory for the source of misinformation at different retention intervals. Subjects viewed a slide presentation, read a narrative containing misinformation, and, either 10 minutes or 1 week later, completed a recognition test about details seen in the slides and about the source of these details. After the longer retention interval in both experiments, participants were more likely to agree that they had seen misleading information and were also more likely to incorrectly associate the misinformation with the slide event. Theoretical implications of these findings are considered.     

Remembering past emotions: The role of current appraisals

This research assessed the stability of memory for emotions over time, and the relationship between current appraisals and memory for emotions. A week after the televised announcement of the verdict in the criminal trial of Mr Orenthal James (O.J.) Simpson, participants were asked to describe their emotional reactions and their appraisals when they first learned of the verdict. After a delay of two months, and again after more than a year, participants recalled their initial emotional reactions and described their current appraisals of the verdict. After two months, the more participants' appraisals of Mr Simpson's innocence or guilt had changed, the less stable were their memories for the intensities of happiness and anger. After two months, and after more than a year, systematic changes in memory for happiness, anger, and surprise were found in directions consistent with current appraisals. These findings replicate and extend the findings of Levine (1997), and suggest that memories for emotional responses are partially reconstructed based on current appraisals of events.     

Fifty years of memory of college grades: accuracy and distortions

One to 54 years after graduating, 276 alumni correctly recalled 3,025 of 3,967 college grades. Omission errors increased with the retention interval, and better students made fewer errors. Accuracy of recall increased with confidence in recall. Eighty-one percent of commission errors inflated the actual grade. Distortions occur soon after graduation, remain constant during the retention interval, and are greater for better students and for courses students enjoyed most. Confidence in recall is unrelated to distortion. Courses that were not freely recalled, but had to be cued, were recalled less accurately and with less distortion. The data support a supplementary theory of memory distortion. The theory assumes that forgetting and distorting memory content are relatively independent processes, that relevant generic memories are used to fill in gaps after episodic memory fails, that systematic distortions affect autobiographical content that is emotionally and motivationally valenced, and that most individuals supplement with content that is emotionally more gratifying than the veridical content. The data conflict with dynamic displacement theories according to which screen memories actively block access to unpleasant veridical content.     

Long-term memory of color stimuli in the jungle crow (Corvus macrorhynchos)

Wild-caught jungle crows (n = 20) were trained to discriminate between color stimuli in a two-alternative discrimination task. Next, crows were tested for long-term memory after 1-, 2-, 3-, 6-, and 10-month retention intervals. This preliminary study showed that jungle crows learn the task and reach a discrimination criterion (80% or more correct choices in two consecutive sessions of ten trials) in a few trials, and some even in a single session. Most, if not all, crows successfully remembered the constantly reinforced visual stimulus during training after all retention intervals. These results suggest that jungle crows have a high retention capacity for learned information, at least after a 10-month retention interval and make no or very few errors. This study is the first to show long-term memory capacity of color stimuli in corvids following a brief training that memory rather than rehearsal was apparent. Memory of visual color information is vital for exploitation of biological resources in crows. We suspect that jungle crows could remember the learned color discrimination task even after a much longer retention interval.     

Implicit long-term memory for duration in young children

The aim of the present study was to investigate young children's ability to maintain in long-term memory a duration of an action they have previously experienced (i.e., implicit long-term memory for duration). Children aged 3 and 5 years were trained to produce an action for 5 s by simultaneous imitation of the experimenter's action. Then, they were tested after a retention interval lasting for 1, 24, or 48 hours (Experiment 1), or 6 days, 6 weeks, or 6 months (Experiment 2). The results showed that the young children remembered the learned duration after 48 hours and 6 months at the age of 3 and 5 years, respectively, although the temporal performance decreased at the 1 hour and the 6 weeks retention intervals for the first and the second age group. These findings are discussed in the framework of a discrepancy in the memory retention of duration as a function of the nature of the memory system, i.e., implicit or explicit.     

Short-term memory in the pigeon: delayed-pair-comparison procedures and some results.

A discrete-trials, delayed-pair-comparison procedure was developed to study visual short-term memory for tilted lines. In four experiments, pigeons' responses on left or right keys were reinforced with food depending on whether a comparison stimulus was or was not the same as a standard stimulus presented earlier in the same trial. In Experimental I, recall was an increasing function of the exposure time of the to-be-remembered stimulus and was a decreasing function of the retention interval. In Experiment II, retroactive interference was investigated: recall was poorer after a retention interval during which was presented either a tilted line or contextual stimuli in the form of the illuminated experimental chamber. In Experiment III, a subject was required to engage, throughout the retention interval, in one or the other of two different behaviors, depending on which of two stimuli a subject was to remember. This mnemonic strategy vastly improved recall after 15- and 20-second retention intervals. In Experiment IV, the opposite end of the performance continuum was studied: by combining the effects of a larger stimulus set and the effects of what presumably was an increased memory load, performance was reduced to approximately chance levels after retention intervals shorter than 1 second.     

Adult age differences in short-term memory and subsequent long-term memory for actions.

Short-term memory for actions was investigated for young adult and elderly adult subjects with the Brown-Peterson procedure at retention intervals of 0 and 15 s. The short-term memory trials were followed by the long-term recall of the prior to-be-remembered actions. The 15-s retention interval was filled either with no activity or with 1 of 3 different interfering activities. Verbal interference had little effect on short-term memory at either age level. Actions performed in the interval either by the subjects or by the experimenter produced significantly lower recall scores at each age level, with the decrement being more pronounced for the elderly than for the young subjects. The long-term memory results indicated that successful short-term recall enhanced later long-term recall, regardless of age level.     

Where did I park? A naturalistic study of spatial memory

A naturalistic study of spatial memory having temporary utility was conducted using 32 faculty and staff of a university, who park in non-reserved parking spaces, as subjects. The subjects, who were unaware of the study until interviewed, were asked to indicate on a map the exact location where they had parked their car on that day and on each of the three preceding days. Whereas retention accuracy decreased significantly across days, the recency effect was weak and overall retention proved to be very accurate. Of the subjects who varied their parking location, 88 per cent were able to indicate within three spaces where they parked on the day of the interview, and 58 per cent on the most remote day. Younger females made significantly larger retention errors across the four days than older females and younger and older males. Subjects' overall retention accuracy correlated with their overall confidence in their recollections (γ = .72). Daily ratings of ‘how busy on the job’, reported times left campus each day, parking location variability, particular parking lot used, and number of parking spaces in the distinct locations used were not significantly correlated with retention errors. In follow-up interviews, subjects reported preferring a behavioural, ‘park in a favourite spot’ strategy, with several types of imagery-based cognitive strategies being cited less frequently, and verbal encoding being the least often cited strategy.     

After the storm: enduring differences in mother-child recollections of traumatic and nontraumatic events

Despite a growing literature on the collaborative reminiscing of mothers and children, little is known about the kinds of things mothers and children discuss as they recollect shared traumatic experiences. Do mother-child recollections of a traumatic event differ from their recollections of more benign events? To address this question, mother-child dyads (N=29) discussed a traumatic event, namely a devastating tornado, and two nontraumatic events (one that preceded and one that followed the tornado). Each dyad discussed all three events 4-months post-tornado and again 6 months later. Whereas conversations about both event types (traumatic and nontraumatic) varied with children's age, dyads' recollections of the tornado were significantly longer, more narratively coherent, and more complete than their recollections of nontraumatic events. These differences largely endured over the 6-month retention interval.     

Continuity and discontinuity in memory for threat

Using a paradigm that allows a quasi-continuous tracking of memory performance over time, two experiments were designed to test the hypotheses that (a) persons with a cognitively avoidant style of coping with threat manifest a dissociation between (intact) short-term and (reduced) long-term retrieval of aversive information and (b) persons with a vigilant coping style recall aversive information particularly well after long retention intervals, provided they are free to think about aversive events. Study 1 (N?=?75) showed that avoiders manifest a poor memory for aversive pictures after long retention intervals only. Study 2 (N?=?95) replicated this finding. In addition, manipulation of the cognitive load during the retention interval influenced vigilants’ recall of aversive information in the predicted way. Results indicate that processes occurring during the retention interval are essential for individual difference in memory for aversive information and require similar attention as encoding, appraisal, and retrieval processes.     

GABA(A) receptors determine the temporal dynamics of memory retention

Four experiments studied the role of GABA(A) receptors in the temporal dynamics of memory retention. Memory for an active avoidance response was a nonmonotonic function of the retention interval. When rats were tested shortly (2 min) or some time (24 h) after training, retention was excellent, but when they were tested at intermediate intervals (1-4 h), retention was poor. Activity at GABA(A) receptors was critical for impairing memory retention at the intermediate intervals because injection of the GABA(A) receptor partial inverse agonist FG7142 prior to test significantly improved performance. These retention enhancing effects of FG7142 were dose-dependent and not due to any nonspecific effects of FG7142 on activity. Our results suggest that the temporal dynamics of memory retention may be caused by variations in neurotransmission through the GABA(A) receptor in the post-training period.     

Witnesses stumbling down memory lane: The effects of alcohol intoxication,retention interval,and repeated interviewing

Intoxicated eyewitnesses are often discredited by investigators and in court, but few studies have examined how alcohol affects witnesses’ memory. The primary aim of the present study was to examine how intoxication (alcohol vs. control), retention interval (immediate vs. one week delay), and number of interviews (one vs. two interviews) affect witnesses’ memory. The participants (N?=?99) were randomly assigned to consume either orange juice or alcohol mixed with orange juice, and they all witnessed a filmed mock crime afterwards. The recall took place either (a) immediately and after a one week delay or (b) after a one week delay only. No main effect of alcohol was found on the quantity or quality of the witnesses’ statements. Both intoxicated and sober witnesses recalled more details, and were more accurate, during immediate compared to delayed recall. For witnesses interviewed twice, an average of 30% new details were provided in the second compared to the first interview, and these were highly accurate. In sum, contrary to what one can expect, intoxicated witnesses with a low to moderate blood alcohol concentration (below 0.10%) were reliable witnesses.     

Are false memories more difficult to forget than accurate memories? The effect of retention interval on recall and recognition

What is the effect of retention interval on accurate and false recollection in the Deese, Roediger, and McDermott (DRM) procedure? Previous research has suggested that false recall is more persistent than accurate recall, but the recognition results have been inconsistent. In two parametric studies, we tested recall and recognition for the same DRM lists, over retention intervals that ranged from no delay to a 2-month delay. We found that accurate and false memory were diminished by increases in retention interval, false memory persistence was present for recall and recognition, greater persistence for false memory than for accurate memory was more readily observed for recall than recognition, and the highthreshold (Pr), signal detection (d’), and nonparametric (A’) recognition measures differed in their sensitivity for detecting change. The effect of retention interval on accurate and false memory is consistent with expectations from fuzzy trace theory. In the DRM procedure, truth is not more memorable than fiction.     

Memory representation of alphabetic position and interval information.

The authors conducted 3 sets of experiments. In the 1st set of experiments, participants made alphabetic position estimations. In the 2nd set, participants made interletter distance estimations. In the 3rd set, they made comparative judgments of the alphabetic order of a pair of letters. The results showed that participants had highly accurate ordinal level information about the alphabet in memory but that interval level information was systematically distorted. In addition, alphabetic serial information was found to be used in 2 distinct modes in memory, depending on whether the representation could be contained within the span of immediate memory.     

Recognition memory retention interval and information load

Two experiments were conducted to study the effect of retention interval and information load on short-term recognition memory in retarded subjects. The task consisted of an input trial of 1–15 pictures followed by a test trial of one picture, with the subject having to press different levers to indicate whether the probe picture had been present on the input trial. Retention intervals between input trial and test trial were manipulated over a range of 1–24 sec. Both accuracy and latency of response were measured. Results showed that latency increased and accuracy decreased as a function of both retention interval and number of stimuli. In addition, number of stimuli interacted with retention interval such that accuracy was not affected by retention interval when information input was small, but decreased quite dramatically at longer retention intervals when input was larger. The results were discussed in terms of current memory search models for both normal and retarded subjects.     

Very long-term retention of a novel

This study investigated the very long-term retention of a full-length novel originally studied as part of a university undergraduate course. One hundred and forty former students completed three tests designed to assess retention of Charles Dickens' Hard Times. Retention intervals ranged from 3 to 39 months. Subjects' responses when they were asked to report their most vivid and enduring memory of the novel were consistent with story grammar models which claim that components of a story which are higher in a hierarchy are remembered better than those lower in the hierarchy. A free recall test of the names and roles of the characters in the novel found that retention of both declined rapidly in the first few months following acquisition, that names were forgotten more quickly than roles, and that retention of both had stabilized above baseline before the longest retention interval. These data are interpreted in terms of a schema account of memory retention, in which retention of schematic knowledge (roles), but not non-schematic knowledge (names) can be mediated by abstract knowledge structures. The results of a fact verification test showed that memory for events of high importance in the novel was better than memory for events of low importance, consistent with models that suggest that texts and stories are represented hierarchically in memory. Confidence ratings also declined over time and showed that subjects generally assessed the accuracy of their responses correctly. The significant predictors of memory for the novel were retention interval and the mark obtained on a coursework essay on Hard Times.