Kim van Oorsouw

Acute tryptophan depletion induced by a gelatin-based mixture impairs object memory but not affective behavior and spatial learning in the rat.

One manner to study the role of serotonin (5-HT) in behavioral functions is through nutritional manipulation of its precursor tryptophan (TRP). By means of the method of acute TRP depletion, plasma TRP levels can be reduced in a reversible way in both humans and rats. In the present study a TRP-free protein-carbohydrate mixture was used to investigate the behavioral effects of lowering TRP and 5-HT concentrations in adult male rats. These animals were tested in models of anxiety (open field, home cage emergence test), depression (forced swimming test) and cognition (object recognition test and Morris water escape test). The TRP-free protein-carbohydrate mixture substantially reduced the ratio TRP/SigmaLNAA within 2 and 4 h by 75 and 60%, respectively. It was found that 4 h after administration, the treatment did not affect anxiety-related behavior nor did it cause depressive-like behavior. Also, no treatment effect was found on spatial learning performance in a Morris water escape test. On the other hand, performance in an object recognition test was clearly impaired after TRP depletion. Taken together, these data suggest that acute lowered central 5-HT levels are not associated with changes in affective behavior (i.e. anxiety and depression), but do impair object memory in adult rats.

Skin conductance and memory fragmentation after exposure to an emotional film clip in depersonalization disorder

It is often assumed that when confronted with an emotional event, patients with DPD inhibit information processing. It is also thought that this fosters memory fragmentation. This hypothesis has not been tested in chronic depersonalization. The aim of this study was to investigate the temporal pattern of autonomic responding to emotional material in depersonalization disorder, along with concomitant deficits in subjective and objective memory formation (i.e., difficulties to form a coherent narrative consisting of an ordered sequence of events). Participants with depersonalization disorder (n=14) and healthy control participants (n=14) viewed an emotional video clip while their skin conductance (SC) levels were measured. Peritraumatic dissociation was measured before and after the clip, and memory performance was measured 35 min after viewing. Compared to controls, depersonalized participants exhibited a distinctly different temporal pattern of autonomic responding, characterized by an earlier peak and subsequent flattening of SCLs. Maximum SCLs did not differ between the two groups. Moreover, unlike the control group, depersonalized participants showed no SC recovery after clip offset. In terms of memory performance, patients exhibited objective memory fragmentation, which they also reported subjectively. However, they did not differ from controls in free recall performance. Apparently, emotional responding in DPD is characterized by a shortened latency to peak with subsequent flattening and is accompanied by memory fragmentation in the light of otherwise unremarkable memory functioning.

Detecting malingered memory problems in the civil and criminal arena

Feigning a psychiatric or neurological disorder may be an attractive strategy to obtain all sorts of privileges or disability benefits. In the criminal arena, feigning memory loss for a crime (crime-related amnesia) may be a way for defendants to gain sympathy or to promote a diminished capacity defence. Although crime-related amnesia may, under some circumstances, be genuine, in many cases it is more likely to be malingered. Malingered memory problems are a subtle form of deception and what is true for deceptive behaviour in general is also true for malingering memory loss: on the basis of clinical intuition alone, it is difficult to detect. Fortunately, there are methods and tools to evaluate the authenticity of memory problems. It is important that forensic and clinical psychologists familiarize themselves with these techniques.

The origin of children's implanted false memories: memory traces or compliance?

A longstanding question in false memory research is whether childrens implanted false memories represent actual memory traces or merely result from compliance. The current study examined this question using a response latency based deception task. Forty-five 8-year-old children received narratives about a true (first day at school) and false event (hot air balloon ride). Across two interviews, 58/32% of the participants developed a partial/full false memory. Interestingly, these children also showed higher false recall on an unrelated DRM paradigm compared to children without a false memory. The crucial finding, however, was that the results of the deception task revealed that children with partial and full false memories were faster to confirm than to deny statements relating to the false event. This indicates that childrens implanted false memories reflect actual memory traces, and are unlikely to be explained by mere compliance.

Adversity does not always lead to psychopathology: cognitive reactivity is related to longitudinal changes in resilience

SamenvattingA substantial majority of individuals who are exposed to a traumatic event do not develop any persistent trauma-related psychological symptoms, a phenomenon referred to as resilience. Relying on a sample of undergraduate students (n = 79), the present study investigated whether positive and negative affect and cognitive reactivity to emotional challenges serve as predictors of longitudinal changes in resilience as measured by the Connor-Davidson Resilience Scale. While at initial testing both positive affect and cognitive reactivity were related to resilience, only higher levels of cognitive reactivity predicted a reduction in resilience four months later. These results highlight the relevance of cognitive reactivity for the study of resilience. (Netherlands Journal of Psychology, 65, 62-68.)

Simulating amnesia and memories of a mock crime

Abstract Defendants often feign (i.e. simulate) dissociative amnesia for their crimes. The Symptom Validity Test (SVT) may be used to detect such feigning. Some studies have shown that feigning amnesia for a mock crime has memory-undermining effects. In this study, we wanted to replicate the memory-undermining effects of simulated amnesia. We also examined whether such effects would occur when participants’ memories were evaluated with a SVT. Thirty participants committed a mock crime and then simulated amnesia for it. During a follow-up test, participants were instructed to perform as well as they could on a free recall test and a SVT. Their memory performance was compared with that of a control group (n=30). Although only a minority of simulating participants (7%) was detected by our SVT, the memory-undermining effect of simulating amnesia appeared to be a robust phenomenon. That is, ex-simulators displayed poorer free recall, more commission errors, and lower SVT scores relative to memory performance of honestly responding controls. However, at follow-up testing the poor memory of ex-simulators did not take the form of a real amnesia (i.e. random performance on SVT).

In Vino Veritas? Alcohol, Response Inhibition and Lying

AIMS Despite the widespread belief that alcohol makes the truth come out more easily, we know very little on how alcohol impacts deception. Given that alcohol impairs response inhibition, and that response inhibition may be critically involved in deception, we expected that alcohol intake would hamper lying. METHODS In total, 104 volunteers were tested at a science festival, where they had the opportunity to drink alcohol. Stop-Signal Reaction Times (SSRTs) served as operationalization of response inhibition. Differences in error rates and reaction times (RTs) between lying and truth telling served as indicators of the cognitive cost of lying. RESULTS Higher blood alcohol concentration was related to longer SSRTs, but unrelated to the cognitive costs of lying. CONCLUSION This study validates previous laboratory research on alcohol and response inhibition in a realistic drinking environment, yet failed to find an effect of alcohol on lying. Implications of these findings and for the role of response inhibition in lying are discussed.

Placebo’s, verwachtingen en daderamnesie: twee gevalsstudies

SamenvattingHet komt geregeld voor dat daders zeggen geen enkele herinnering te hebben aan het door hen gepleegde misdrijf. Zo’n vorm van amnesie kan gesimuleerd zijn, maar dat hoeft niet. In het laatste geval spelen negatieve verwachtingen over het eigen geheugen mogelijk een sleutelrol. Bij twee daders die werden behandeld in een forensische kliniek, gingen we op exploratieve wijze na of het beweerde geheugenverlies kon worden verminderd door hun verwachtingen te beïnvloeden. De deelnemers kregen een placebo met de mededeling dat herinneringen aan het delict hierdoor zouden kunnen terugkeren. De placebo leek te werken bij een deelnemer die negatieve verwachtingen had over zijn geheugen voor het delict. Het placebo-effect bleef uit bij een deelnemer, die zijn geheugenbeperking hoogstwaarschijnlijk veinsde. Wellicht kunnen placebo’s vruchtbaar worden ingezet bij de behandeling van daders die zeggen geheugenverlies te hebben. Succes is echter afhankelijk van het type geheugenverlies. Het gebruik van goede diagnostische instrumenten, om bijvoorbeeld het simuleren van geheugenverlies op te sporen, is daarbij belangrijk.AbstractDefendants often claim to have no memory of the crime they committed. Such claims of amnesia can be simulated, but may also have a bona fide background. That is, claims of amnesia may be based on negative expectations about the quality of ones own memory. Manipulating these expectancies using memory-enhancing placebos may, perhaps, counteract expectancy-based claims of amnesia. In the current case-study, two forensic patients claiming amnesia were given memory-enhancing placebos with the instruction that they might restore crime-related memories. The placebo appeared to be partially successful in one participant, who had strong beliefs about the reality of crime-related amnesia. No placebo-effect occurred in a participant, who most likely feigned his amnesia. Memory-enhancing placebos may be successful when forensic patients claim amnesia, but their success depends on the type of memory loss (e.g., simulated or bona fide). Additional instruments measuring the tendency to simulate psychiatric symptoms are informative in this type of patient-directed research

Can implicit measures detect source information in crime-related amnesia?

ABSTRACT Participants who are asked to simulate amnesia for a mock crime have a weaker memory for this event when they have to give up their role as a feigner, than those who are not asked to feign memory loss. According to the source monitoring framework (SMF), this memory-undermining effect of simulating amnesia for a crime would be due to misattribution of the right source of information. However, we know that the content of self-generated information (e.g., feigned version of the crime) might be preserved and recognised over time as a result of elaborative cognitive processing. In the present study, we aimed to contrast these two explanations. We showed participants a mock crime video and we instructed them to either feign amnesia (simulators) or confess the mock crime (confessors). Next, a free recall memory test was administered. After one week, participants were asked to perform a personalised source monitoring task using the autobiographical Implicit Association Test (aIAT). As predicted, we found that simulators were able to discriminate the content of their self-generated feigned story of the crime from the original version. Moreover, simulators were quicker than confessors at the aIAT task. Practical and theoretical implications of our results are discussed.

Feigning Amnesia Moderately Impairs Memory for a Mock Crime Video

Previous studies showed that feigning amnesia for a crime impairs actual memory for the target event. Lack of rehearsal has been proposed as an explanation for this memory-undermining effect of feigning. The aim of the present study was to replicate and extend previous research adopting a mock crime video instead of a narrative story. We showed participants a video of a violent crime. Next, they were requested to imagine that they had committed this offense and to either feign amnesia or confess the crime. A third condition was included: Participants in the delayed test-only control condition did not receive any instruction. On subsequent recall tests, participants in all three conditions were instructed to report as much information as possible about the offense. On the free recall test, feigning amnesia impaired memory for the video clip, but participants who were asked to feign crime-related amnesia outperformed controls. However, no differences between simulators and confessors were found on both correct cued recollection or on distortion and commission rates. We also explored whether inner speech might modulate memory for the crime. Inner speech traits were not found to be related to the simulating amnesia effect. Theoretical and practical implications of our results are discussed.