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Biomedical subjects

Harald Merckelbach

Publications and source records attributed to Harald Merckelbach.

At least 37 records · Page 2Linked to original sources
PubMed2004

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.

Adult↗
PubMed2004

Traumatic stress, brain changes, and memory deficits: a critical note.

Memory deficits are frequently observed in posttraumatic stress disorder. According to some authors, these memory impairments are a result of hippocampal damage caused by traumatic stress. This article contains a critical review of studies on changes in hippocampal volume and memory performance in posttraumatic stress disorder. We conclude that most studies in this area suffer from methodological weaknesses and therefore do no allow for firm conclusions about the causal linkage among traumatic stress, hippocampal functioning, and memory. Suggestions for future research, circumventing methodological flaws, are given.

Adolescent↗
PubMed2004

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.

Adolescent↗
PubMed2004

Correlates of the Gudjonsson Suggestibility Scale in delinquent adolescents.

Correlations between scores on the Gudjonsson Suggestibility Scale and a number of relevant personality characteristics, i.e., intelligence, memory, social inadequacy, social desirability, and fantasy proneness, were examined in a sample of 71 delinquent boys. Analysis showed that intelligence and memory were negatively related to suggestibility scores. That is, lower memory and intelligence were associated with higher suggestibility. No significant correlations were found between suggestibility and other personality characteristics.

Adolescent↗
PubMed2004

How children remember neutral and emotional pictures: boundary extension in children's scene memories.

Boundary extension is the tendency to remember more of a scene than was actually shown. The dominant interpretation of this memory illusion is that it originates from schemata that people construct when viewing a scene. Evidence of boundary extension has been obtained primarily with adult participants who remember neutral pictures. The current study addressed the developmental stability of this phenomenon. Therefore, we investigated whether children aged 10-12 years display boundary extension for neutral pictures. Moreover, we examined emotional scene memory. Eighty-seven children drew pictures from memory after they had seen either neutral or emotional pictures. Both their neutral and emotional drawings revealed boundary extension. Apparently, the schema construction that underlies boundary extension is a robust and ubiquitous process.

Affect↗
PubMed2004

Accuracy, completeness, and consistency of emotional memories.

Judges and lawyers often consider inconsistent testimonies to be inaccurate. We addressed this assumption by asking undergraduate students on 2 occasions to write detailed accounts of violent movie fragments they had seen. These accounts were evaluated in terms of accuracy, completeness, and consistency. Experiment 1 showed that accounts tended to be accurate. Moreover, first accounts were marginally more complete than second accounts. The number of inconsistencies between the 2 accounts was not significantly related to their accuracy. Experiment 2 sought to replicate these findings using a more emotionally upsetting movie fragment. Results were highly similar to those of Experiment 1 in that accounts tended to be accurate but incomplete. Inconsistencies were not significantly related to the accuracy of participants' accounts. In line with previous research, we found that accounts of emotional events can be highly accurate but tend to be incomplete. More importantly, inconsistencies cannot be seen as valid predictors of testimonial inaccuracy.

Adolescent↗
PubMed2004

Alcoholic blackout for criminally relevant behavior.

Some criminal suspects claim to have had an alcohol-induced blackout during crimes they have committed. Are alcoholic blackouts a frequently occurring phenomenon, or are they merely used as an excuse to minimize responsibility? Frequency and type of blackout were surveyed retrospectively in two healthy samples (n = 256 and n = 100). Also, a comparison of blood alcohol concentrations was made between people who did and those who did not claim a blackout when stopped in a traffic-control study (n = 100). In the two survey studies, blackouts were reported frequently by the person himself (or herself) and others (67% and 76%, respectively) in contrast to the traffic-control study (14%), in which blackouts were reported only when persons were involved in an accident. These results indicate that although blackouts during serious misbehavior are reported outside the court, both the denial and the claim of alcoholic blackout may serve a strategic function.

Adolescent↗
PubMed2003

Fear of the beast: a prospective study on the effects of negative information on childhood fear.

The current study examined the effects of negative information on the enhancement of childhood fear. A large group of normal primary school children aged between 4 and 12 years (N=285) received either negative or positive information about an unknown, doglike animal, called 'the beast'. Children's fears were assessed at three points in time: before, directly after, and one week after the information about the beast was provided (i.e., pre-, post- and follow-up assessment). Results showed that type of information changed children's fear of the beast in the predicted direction with negative information increasing fear levels and positive information decreasing fear levels. This was not only the case directly after the experimental manipulation but also at one week follow-up. Furthermore, fear of the beast appeared to generalize, that is, children who became more fearful of the beast after receiving negative information, also became more apprehensive of other dogs and predators.

Age Factors↗
PubMed2003

Amnesia, flashbacks, nightmares, and dissociation in aging concentration camp survivors.

The current study examined to what extent war memories of Dutch survivors of Japanese/Indonesian concentration camps display characteristics that are often believed to be typical for traumatic memories. Twenty-nine survivors were interviewed about amnesia, flashbacks, nightmares and the sensory quality of their most upsetting war memories. In addition, they completed self-report scales measuring post-traumatic stress symptoms and dissociation. In contrast to prevailing notions, amnesia, flashbacks and nightmares were not typical for this sample. Neither were traumatic memories characterized by a particularly strong sensory loading. Post-traumatic stress symptoms were not related to dissociative experiences. At least for this group of aging survivors, it appears that the pathogenic potential of traumatic memories has more to do with their extremely aversive content than with a qualitatively different type of organization of these memories.

Aged↗
PubMed2003

The links between the Adolescent Dissociative Experiences Scale (A-DES), fantasy proneness, and anxiety symptoms.

The purpose of this study was to further examine the psychometric properties of the Adolescent Dissociative Experiences Scale (A-DES). A sample of normal adolescents (N = 331) aged 12 to 18 years completed the A-DES and questionnaires measuring posttraumatic stress disorder (PTSD) symptoms, other anxiety disorder symptoms, and fantasy proneness. Factor analysis indicated that the A-DES, at least in nonreferred youths, is assessing a single dimension of dissociation. Furthermore, A-DES scores are not only significantly related to PTSD symptoms but also to other anxiety disorder symptoms (i.e., generalized anxiety disorder, obsessive-compulsive disorder, and panic disorder) and fantasy proneness. Theoretical and practical implications of these findings are briefly discussed.

Adolescent↗
PubMed2003

Anxiety, threat perception abnormalities, and emotional reasoning in nonclinical Dutch children.

Examined the relation between childhood anxiety and threat-perception abnormalities using vignettes in which external (i.e., exposure to potential threat cues) and internal (i.e., experience of anxiety responses) information were systematically varied. Nonclinical children (N = 156) aged 8 to 13 years completed anxiety questionnaires and were then exposed to 3 types of stories: ambiguous stories, ambiguous + anxiety-response stories, and nonthreatening stories. From children's responses to these stories, a number of threat-perception indexes were derived. Results showed that both external and internal information inflated children's perception of threat. Further, high levels of anxiety were accompanied by enhanced threat perception in response to external threat cues. Finally, little evidence was found that high levels of anxiety, and in particular of anxiety sensitivity, were associated with a greater tendency to use internal information (i.e., emotional reasoning). Potential avenues for future studies on anxiety-related threat-perception distortions are briefly discussed.

Adolescent↗
PubMed2003

Thought-action fusion and schizotypy in undergraduate students.

OBJECTIVE: To examine the relationship between thought-action fusion (TAF) and schizotypy. METHOD: In two separate samples of undergraduate students (Ns = 77 and 64), correlations were computed between a measure of TAF and indices of schizotypy and fantasy proneness. RESULTS: Positive correlations were found between TAF and various aspects of schizotypy (i.e. perceptual aberration, magical ideation, schizotypal personality characteristics, disposition to hallucinate). However, correlations between TAF and schizotypy no longer attained significance when controlling for fantasy proneness. CONCLUSION: At least in the non-clinical population, the connection between TAF and schizotypy seems to be a by-product of fantasy-prone individuals' tendency to report unusual experiences.

Adolescent↗
PubMed2003

The Guilty Knowledge Test and the modified Stroop task in detection of deception: an exploratory study.

The current study tested whether a simple Stroop paradigm can be used to detect deceptive behavior. 40 university students (34 women), half of whom committed a mock crime, were administered a Guilty Knowledge Test and modified Stroop task to detect guilt or innocence. The Guilty Knowledge Test is a well-known psychophysiological detection method, which consists of multiple-choice questions about details of the crime while skin conductance is recorded. Subjects possessing guilty knowledge are expected to show enhanced differential responses to the relevant stimuli. The modified Stroop task required color-naming of colored words related to the mock crime or an irrelevant crime. Each version of the Stroop task was presented in story form. Subjects possessing guilty knowledge were expected to produce larger reaction times to the relevant version relative to the irrelevant version. The test correctly identified 100% of innocent participants and 78% of guilty participants. In contrast, Stroop interference. i.e., reaction times for irrelevant crime details subtracted from those for mock crime details, did not differentiate between the two groups, suggesting that the story form of the Stroop paradigm is not suitable for lie detection.

Adolescent↗
PubMed2003

Boundary distortions for neutral and emotional pictures.

In two experiments, we examined Safer, Christianson, Autry, and Osterlund's (1998) claim that when emotional material is remembered, tunnel memory (i.e., the tendency to remember less of a scene than was actually shown) occurs. In Experiment 1, 81 undergraduate students drew photographs from memory after having briefly seen either four neutral or four emotional photographs. Both neutral and emotional drawings revealed boundary extension (i.e., the tendency to remember more of a scene than was actually shown). Experiment 2 relied on the camera distance paradigm (Intraub, Bender, & Mangels, 1992). In a recognition test, 60 undergraduate students judged the camera distance of previously seen neutral or emotional photographs. The majority of them demonstrated accurate judgments and neither extended nor restricted picture boundaries. Those participants who made an error more often displayed a boundary extension than a tunnel memory error. Taken together, our results suggest that boundary extension for neutral and emotional photographs is a more robust phenomenon than its counterpart, tunnel memory.

Adolescent↗
PubMed2003

Diagnostic accuracy of the Structured Inventory of Malingered Symptomatology (SIMS) in detecting instructed malingering.

This article addresses the psychometric properties of the Dutch translation of the Structured Inventory of Malingered Symptomatology (SIMS) when administered to undergraduate psychology students as well as psychiatric inpatients. Findings show that this SIMS version possesses good test-retest reliability and internal consistency. Also, simulation findings indicate that undergraduate students instructed to simulate pathology display higher SIMS scores than either normal controls or psychiatric inpatients. Data pooled over several samples (n=298) yielded sensitivity, specificity, and positive predictive power (PPP) rates that were all relatively high (>/=0.90). All in all, our findings provide a basis for cautious optimism regarding the usefulness of the SIMS as a screening tool for malingering.

Adult↗
PubMed2002

The connection between cognitive development and specific fears and worries in normal children and children with below-average intellectual abilities: a preliminary study.

The present study explored the relationship between cognitive development and anxiety phenomena in 4-12-year-old children. Fears and worries of normal children (n=176) were compared to those of children with below-average intellectual abilities (children with BAIA; n=105). We evaluated to what extent level of cognitive development as indexed by a Piagetian conservation task was associated with the presence of fears and worries. While normal children and children with BAIA did not differ with regard to the content of their fears and worries, normal children more frequently reported such anxiety phenomena during the semi-structured Anxiety Interview than did children with BAIA. Furthermore, in normal children, evidence was found to suggest that level of cognitive development contributes to the experience of fears and worries. That is, anxiety phenomena were more prevalent among those children who passed a Piagetian conservation task. However, when anxiety phenomena were assessed by means of the Koala Fear Questionnaire (KFQ), a different picture emerged. KFQ data suggested that fears were less frequent in normal children and those children with BAIA who had a higher level of cognitive functioning. Apparently, the Anxiety Interview and the KFQ tap quite different aspects of anxiety. The KFQ seems to measure primitive fears that are likely to be prevalent among children with limited cognitive capacity, whereas the Anxiety Interview assesses more sophisticated anxiety phenomena that probably depend on high levels of cognitive functioning.

Adaptation, Psychological↗
PubMed2002

The etiology of specific fears and phobias in children: a critique of the non-associative account.

The non-associative account of phobic etiology assumes that a number of specific fears (e.g., fear of heights, water, spiders, strangers, and separation) have an evolutionary background and may occur in the absence of learning experiences (e.g., conditioning). By this view, these specific fears pertain to stimuli that once posed a challenge to the survival of our prehistoric ancestors. Accordingly, they would emerge spontaneously during the course of normal development and only in a minority of individuals, these specific fears would persist into adulthood. While the non-associative approach has generated interesting findings, several critical points can be raised. First, it capitalizes on negative findings, i.e., the failure to document learning experiences (e.g., conditioning, modeling) in the history of phobic children. Second, it largely ignores factors that have been found to be crucial for the acquisition of early childhood fears (e.g., the developmental level of the child, stimulus characteristics such as novelty, aversiveness, and unpredictability, and early experience with uncontrollable events). As an alternative to the non-associative account, we briefly describe a multifactorial model of childhood fears and phobias.

Child↗