Ingrid Candel

True or false? Memory is differentially affected by stress-induced cortisol elevations and sympathetic activity at consolidation and retrieval

Adrenal stress hormones released in response to acute stress may yield memory-enhancing effects when released post-learning and impairing effects at memory retrieval, especially for emotional memory material. However, so far these differential effects of stress hormones on the various memory phases for neutral and emotional memory material have not been demonstrated within one experiment. This study investigated whether, in line with their effects on true memory, stress and stress-induced adrenal stress hormones affect the encoding, consolidation, and retrieval of emotional and neutral false memories. Participants (N=90) were exposed to a stressor before encoding, during consolidation, before retrieval, or were not stressed and then were subjected to neutral and emotional versions of the Deese-Roediger-McDermott word list learning paradigm. Twenty-four hours later, recall of presented words (true recall) and non-presented critical lure words (false recall) was assessed. Results show that stress exposure resulted in superior true memory performance in the consolidation stress group and reduced true memory performance in the retrieval stress group compared to the other groups, predominantly for emotional words. These memory-enhancing and memory-impairing effects were strongly related to stress-induced cortisol and sympathetic activity measured via salivary alpha-amylase levels. Neutral and emotional false recall, on the other hand, was neither affected by stress exposure, nor related to cortisol and sympathetic activity following stress. These results demonstrate the importance of stress-induced hormone-related activity in enhancing memory consolidation and in impairing memory retrieval, in particular for emotional memory material.

Valence and the development of immediate and long-term false memory illusions

Across five experiments we examined the role of valence in childrens and adults’ true and false memories. Using the Deese/Roediger-McDermott paradigm and either neutral or negative-emotional lists, both adults’ (Experiment 1) and childrens (Experiment 2) true recall and recognition was better for neutral than negative items, and although false recall was also higher for neutral items, false recognition was higher for negative items. The last three experiments examined adults’ (Experiment 3) and childrens (Experiments 4 and 5) 1-week long-term recognition of neutral and negative-emotional information. The results replicated the immediate recall and recognition findings from the first two experiments. More important, these experiments showed that although true recognition decreased over the 1-week interval, false recognition of neutral items remained unchanged whereas false recognition of negative-emotional items increased. These findings are discussed in terms of theories of emotion and memory as well as their forensic implications.

Disgust and psychopathological symptoms in a nonclinical sample

There is little doubt that disgust sensitivity plays a role in the development of small animal phobias. However, it has been suggested that the basic emotion of disgust is implied in a broad range of psychopathological conditions. The present study examined the relationship between disgust sensitivity and symptoms of phobias (other than animal phobias), obsessive-compulsive disorder, depression, and eating disorder in a nonclinical sample. Undergraduate psychology students were asked to complete the Disgust Sensitivity Questionnaire, as well as measures of phobic (Fear Questionnaire), obsessive-compulsive (Maudsley Obsessive-Compulsive Inventory), depressive (Beck Depression Inventory), and eating disorder (Restraint Scale) symptomatology. Results showed that disgust sensitivity was only related to symptoms of agoraphobia and obsessive-compulsive disorder. The present findings cast doubts on the idea that disgust sensitivity is a central factor underlying a broad range of psychopathological conditions.

Traumatic memories of war veterans : Not so special after all

Several authors have argued that traumatic experiences are processed and remembered in a qualitatively different way from neutral events. To investigate this issue, we interviewed 121 Croatian war veterans diagnosed with posttraumatic stress disorder (PTSD) about amnesia, intrusions (i.e., flashbacks and nightmares), and the sensory qualities of their most horrific war memories. Additionally, they completed a self-report scale measuring dissociative experiences. In contrast to what one would expect on the basis of theories emphasizing the special status of traumatic memories, amnesia, and high frequency intrusions were not particularly typical for our sample of traumatized individuals. Moreover, traumatic memories were not qualitatively different from neutral memories with respect to their stability and sensory qualities. The severity of PTSD symptoms was not significantly correlated with dissociative experiences. Our findings do not support the existence of special memory mechanisms that are unique to experiencing traumatic events.

Script knowledge enhances the development of children’s false memories

We examined whether script knowledge contributes to the development of childrens false memories. Sixty 7-year-old and 60 11-year-old children listened to false narratives describing either a high-knowledge event (i.e., fingers being caught in a mousetrap) or a low-knowledge event (i.e., receiving a rectal enema) that were similar in terms of plausibility and pleasantness. Moreover, half of the children in each condition received additional suggestive details about the false events. Across two interviews, children had to report everything they remembered about the events. Script knowledge affected childrens false memories in that both younger and older children developed more false memories for the high-knowledge event than for the low-knowledge event. Moreover, at the first interview, additional suggestive details inhibited the development of childrens images into false memories.

Measuring interrogative suggestibility in children: Reliability and validity of the bonn test of statement suggestibility

Abstract The Bonn Test of Statement Suggestibility (BTSS) has been proposed as a tool for measuring individual differences in interrogative suggestibility in 4 to 10 year old children. The current study sought to evaluate the psychometric properties of a Dutch version of the BTSS (BTSSNL) in a sample of 48 primary school children. Test-retest stability and internal consistency of the two subscales of the BTSS-NL (i.e., the Yield and Shift scale) proved to be sufficient. Indirect support for the validity of the BTSS-NL was found in that younger children had higher BTSS-NL scores than older children. Also, children who were judged by their teacher as highly suggestible displayed higher scores on the Yield scale of the BTSS-NL than children who were not particularly suggestible according to their teacher. While these results indicate that the BTSS-NL is a valuable research instrument for measuring individual differences in childrens suggestibility, more large scale studies are needed to determine whether the BTSS-NL can be used as a forensic tool.

Children's false memories: different false memory paradigms reveal different results

The aim of the present study was to examine whether two different false memory paradigms (DRM vs suggestion) produce similar results. In Experiment 1, 100 children from four age groups (5/6-year-olds, 7/8-year-olds, 9/10-year-olds, and 11/12-year-olds) were instructed to remember lists of semantically related words (DRM paradigm) and to complete a childrens suggestibility measure (i.e. BTSS-NL). Results showed that childrens false memories for non-presented words increased with age while accepting suggestive information decreased with age. Moreover, no significant relation was found between childrens susceptibility to the DRM illusion and concurring to suggestive information. In Experiment 2, DRM false recall and recognition was compared between children with (n=20) and without (n=20) false memories for entire events. Children with implanted false memories did not falsely recall and recognize more critical lures than children without implanted false memories. This study shows that childrens DRM intrusions are not related to their acceptance of suggestive information.

Detection of feigned cognitive dysfunction using special malinger tests: a simulation study in naïve and coached malingerers

The aim of the present study was to compare the accuracy of the Amsterdam Short Term Memory (ASTM) test with that of the Structured Inventory of the Malingered Symptomatology (SIMS) in detecting feigning of cognitive dysfunction in naïve and coached participants. Ninety undergraduate students were administered the ASTM and the SIMS and asked to respond honestly (controls; n = 30), or instructed to malinger cognitive dysfunction due to head injury. Before the both instruments were administered, naïve malingerers received no further information (n = 30), whereas coached malingerers were given some information about brain injury and a warning not to exaggerate symptoms (n = 30). Both tests correctly classified 90% of the naïve malingerers. The ASTM detected 70% of the coached malingerers, whereas the SIMS continued to detect 90% of them. The findings suggest that coaching undermines the diagnostic accuracy of the ASTM, but does not seem to influence the accuracy of the SIMS.

'You didn't take Lucy's skirt off': The effect of misleading information on omissions and commissions in children's memory reports

Purpose. The current study explored how misleading information affects childrens omissions and commissions over time. Method. Fifty-nine younger (Mage = 4.16) and fifty-nine older (Mage = 9.44) children were instructed to remove three pieces of clothing from a puppet. Half of them were provided with false evidence that they had removed only two items, while the other half were provided with false evidence that they had removed a fourth piece of clothing. In three neutral interviews separated by 1-week intervals, children had to report which pieces of clothing they had removed. Results. Overall, omission and commission errors significantly decreased over time, although this pattern was more pronounced for omission errors. Younger and older children were equally likely to make omission errors, whereas commission errors were more typical for younger than for older children. Also, we found that commission errors more readily occur than omission errors. Conclusion. Even when childrens memory reports pertain to an event in which they actively participated, misleading information may elicit omission and commission errors, with especially the latter category being very persistent over time.

Detecting deception of war-related posttraumatic stress disorder

There is considerable concern about the ease with which posttraumatic stress disorder (PTSD) symptoms can be simulated, especially when compensation-seeking is a factor. The current study investigated whether the Morel Emotional Numbing Test (MENT) could discriminate between compensation-seeking and non-compensation-seeking war veterans: 49 compensation-seeking veterans and 70 veterans seeking treatment completed the MENT, an instrument aimed to detect overreporting of PTSD symptoms. Results showed that compensation-seeking war veterans scored significantly higher on the MENT than non-compensation-seeking war veterans. Also, the MENTs accuracy rates were very promising. This study shows that the MENT is an adequate tool for evaluating PTSD claims. We recommend using the MENT as a screening tool, whereby respondents above a certain cutoff should be evaluated more carefully to assess the degree to which their posttraumatic symptoms are genuine.