Elke Geraerts

A detailed analysis of rats' spatial memory in a probe trial of a Morris task

In the present study, we evaluated the search behavior of rats during a probe trial of a Morris water escape task. More specifically, the spatial memory during different stages of a 2 min probe trial in different zones was examined. After rats were trained for 4 days with four trials per day, their spatial memory was tested in a first probe trial. The rats showed a preference for the target quadrant during each of four 30-s intervals. The time in the annulus decreased across the four 30-s intervals. The preference for the previous target quadrant was also observed in a second probe trial, when the rats had received additional training for 4 days with four trials per day. However, the time spent in the annulus was highest during the first 30-s of the probe trial, and was lower and similar during the next three 30-s intervals. Therefore, probe trials of 60s seem to underestimate the spatial ability of rats. It appears that using a quadrant for assessing the performance may overestimate the spatial ability of a rat. Our findings suggest that the evaluation of the spatial memory of rats in a probe trial in the Morris water escape task requires a more detailed analysis.

ACUTE STRESS ENHANCES MEMORY FOR EMOTIONAL WORDS, BUT IMPAIRS MEMORY FOR NEUTRAL WORDS

This article examined effects of acute stress on memory for neutral and emotional words. Participants (n = 40) were exposed to either a psychosocial stressor or a control task, followed by a memory test. The stress hormone cortisol was measured in saliva before and after stress induction and after the memory test. Acute stress had a differential effect on memory such that recall of neutral words was impaired, whereas that of emotional words was enhanced. These effects on memory performance were not mediated by cortisol. The authors conclude that it makes little sense to speculate about memory effects and elevated levels of cortisol because such effects might depend on the valence of the material that is learned.

Fantasy proneness, but not self-reported trauma is related to DRM performance of women reporting recovered memories of childhood sexual abuse

Extending a strategy previously used by , we administered a neutral and a trauma-related version of the Deese-Roediger-McDermott paradigm to a sample of women reporting recovered (n=23) or repressed memories (n=16) of childhood sexual abuse (CSA), women reporting having always remembered their abuse (n=55), and women reporting no history of abuse (n=20). We found that individuals reporting recovered memories of CSA are more prone than other participants to falsely recalling and recognizing neutral words that were never presented. Moreover, our study is the first to show that this finding even held when trauma-related material was involved. Correlational analyses revealed that fantasy proneness, but not self-reported traumatic experiences and dissociative symptoms were related to false recall and false recognition.

Lasting False Beliefs and Their Behavioral Consequences

False beliefs and memories can affect peoples attitudes, at least in the short term. But can they produce real changes in behavior? This study explored whether falsely suggesting to subjects that they had experienced a food-related event in their childhood would lead to a change in their behavior shortly after the suggestion and up to 4 months later. We falsely suggested to 180 subjects that, as children, they had gotten ill after eating egg salad. Results showed that, after this manipulation, a significant minority of subjects came to believe they had experienced this childhood event even though they had initially denied having experienced it. This newfound autobiographical belief was accompanied by the intent to avoid egg salad, and also by significantly reduced consumption of egg-salad sandwiches, both immediately and 4 months after the false suggestion. The false suggestion of a childhood event can lead to persistent false beliefs that have lasting behavioral consequences.

Cognitive Mechanisms Underlying Recovered-Memory Experiences of Childhood Sexual Abuse

People sometimes report recovering long-forgotten memories of childhood sexual abuse. The memory mechanisms that lead to such reports are not well understood, and the authenticity of recovered memories has often been challenged. We identified two subgroups of people reporting recovered memories of childhood sexual abuse. These subgroups differed dramatically in their cognitive profiles: People who recovered memories of abuse through suggestive therapy exhibited a heightened susceptibility to the construction of false memories, but showed no tendency to underestimate their prior remembering. Conversely, people who recovered memories of abuse spontaneously showed a heightened proneness to forget prior incidences of remembering, but exhibited no increased susceptibility to false memories. This double dissociation points to mechanisms that underlie recovered-memory experiences and indicates that recovered memories may at times be fictitious and may at other times be authentic.

Dissociation in undergraduate students: disruptions in executive functioning

The concept of dissociation refers to disruptions in attentional control. Attentional control is an executive function. Few studies have addressed the link between dissociation and executive functioning. Our study investigated this relationship in a sample of undergraduate students (N = 185) who completed the Dissociative Experiences Scale and the Random Number Generation Task. We found that minor disruptions in executive functioning were related to a subclass of dissociative experiences, notably dissociative amnesia and the Dissociative Experiences Scale Taxon. However, the two other subscales of the Dissociative Experiences Scale, measuring depersonalization and absorption, were unrelated to executive functioning. Our findings suggest that a failure to inhibit previous responses might contribute to the pathological memory manifestations of dissociation.

A New Solution to the Recovered Memory Debate

The controversy regarding recovered memories of childhood sexual abuse (CSA) has been characterized by two perspectives. According to one perspective, some people repress their memories of abuse because these experiences have been so emotionally traumatic, and they become capable of recalling the CSA only when it is psychologically safe to do so many years later. According to the other perspective, many reports of recovered memories of sexual abuse are false memories, often inadvertently fostered by therapists. In this article, we provide evidence for a third interpretation that applies to a subset of people reporting recollections of CSA; it does not require the concepts of repression, trauma, or false memory. These people did not experience their CSA as traumatic; they either failed to think about their abuse for years or forgot their previous recollections, and they recalled their CSA spontaneously after encountering reminders outside of psychotherapy. Their recovered memories are corroborated at the same rate as those of people who never forgot their abuse. Hence, recalling CSA after many years is not the same thing as having recalled a previously repressed memory of trauma.

The Reality of Recovered Memories: Corroborating Continuous and Discontinuous Memories of Childhood Sexual Abuse

Although controversy surrounds the relative authenticity of discontinuous versus continuous memories of childhood sexual abuse (CSA), little is known about whether such memories differ in their likelihood of corroborative evidence. Individuals reporting CSA memories were interviewed, and two independent raters attempted to find corroborative information for the allegations. Continuous CSA memories and discontinuous memories that were unexpectedly recalled outside therapy were more likely to be corroborated than anticipated discontinuous memories recovered in therapy. Evidence that suggestion during therapy possibly mediates these differences comes from the additional finding that individuals who recalled the memories outside therapy were markedly more surprised at the existence of their memories than were individuals who initially recalled the memories in therapy. These results indicate that discontinuous CSA memories spontaneously retrieved outside of therapy may be accurate, while implicating expectations arising from suggestions during therapy in producing false CSA memories.

Forgetting of Prior Remembering in Persons Reporting Recovered Memories of Childhood Sexual Abuse

Case studies of individuals reporting recovered memories of childhood sexual abuse suggest that some overestimate their prior forgetting of the abuse. People reporting recovered or continuous memories of childhood sexual abuse and control subjects reporting no history of abuse participated in two experiments examining this “forgot it all along” phenomenon. Participants in Experiment 1 were more likely to forget that they had previously recalled a studied item if they were cued to think of it differently on two recall tests than if they were cued to think of it in the same way on the two tests. This effect was stronger for recovered-memory participants than for continuous-memory and control participants. In Experiment 2, participants recalled autobiographical events three times over a period of 4 months. Much as in Experiment 1, they underestimated prior remembering when the events had been recalled in a different emotional frame (positive vs. negative) on the previous occasion. This underestimation was more pronounced for recovered-memory participants than for continuous-memory and control participants.

Autobiographical memory specificity after manipulating retrieval cues in adults reporting childhood sexual abuse

Traumatized samples have relative difficulty in generating specific autobiographical memories on a cue word task, compared to nonexposed controls. Simultaneously, trauma is associated with highly specific intrusive trauma memories in day-to-day life. Possibly, day-to-day intrusions and memories generated to cue words rely on different retrieval processes, with the former dependent on close associations between retrieval cues and specific memory representations (direct retrieval), and the latter on iterative retrieval cycles through a hierarchical memory system (generative retrieval). This study investigated this distinction using two versions of the cue word task, designed to promote generative and direct retrieval, respectively, in participants with or without a history of child sexual abuse (CSA). The data demonstrated that CSA participants were less specific than nonabused controls to generative retrieval cues, but this difference disappeared with direct retrieval cues. This interaction was stronger in CSA participants with relatively greater posttraumatic stress and remained significant when participants with past or current major depressive disorder were excluded and also when only those participants with corroborated CSA were included.