Dissociation in undergraduate students: disruptions in executive functioning

Heterogeneity of associations between dissociation and attention deficit symptoms

Childhood trauma and dissociative experiences are suggested to be predisposing transdiagnostic factors for attention deficit /hyperactivity disorder (ADHD) as well as many psychiatric disorders. Trauma-related symptoms such as motor restlessness, emotional instability, and concentration problems can mimic, trigger, or exacerbate ADHD symptoms. Moreover, given the relationship between ADHD and trauma-induced distress, it has been suggested that dissociative experiences and attention problems may reveal overlapping characteristics. The aim of this study was to investigate the associations between dissociative experiences and attention deficits by carrying out mixture analysis. A thousand and thirty-seven participants volunteered to the online investigation. Participants completed a test battery that included a sociodemographic form as well as the Adult ADHD Severity Rating Scale (ASRS), Wender Utah Rating Scale (WURS), Childhood Trauma Questionnaire (CTQ), Dissociative Experiences Scale (DES), and Somatoform Dissociation Questionnaire (SDQ). Item responses on the DES and attention deficit symptoms as indexed by the ASRS were subjected to latent class analysis. The three-latent-class model outperformed alternative mixture models. Mixture analysis classified the sample into three homogenous subgroups as follows: (1) No/low dissociation or attention problems; (2) Moderate dissociation with attention problems; and (3) High dissociation with attention problems. High dissociators with attention problems were characterized by heightened scores on somatoform dissociation and emotional neglect. No/low dissociation or attention problems latent class reported significantly lower scores on hyperactivity/impulsivity, depression, attention deficit in childhood, and sexual abuse than both moderate and high dissociation latent classes. High dissociators and moderate dissociators significantly differed on conduct problems and physical abuse. We concluded that impulsive hyperactivity, depression, and childhood sexual abuse were common features in heightened dissociation latent classes, as well as attention deficit.

Dissociation and emotion regulation strategies: A meta-analytic review

OBJECTIVE

Clinical and neurobiological models posited that dissociative mechanisms might affect processes involved in emotional generation and regulation. However, there is a lack of a comprehensive theoretical framework that systematically includes dissociation within emotional functioning.

METHODS

The current study aims at conducting a meta-analytic review on the relationship between dissociation and emotion regulation in order to empirically estimate to what extent dissociation is related to emotion regulation processes. The meta-analysis was based on r coefficient as effect size measure, using a random-effect approach.

RESULTS

The meta-analysis included 57 independent studies for a total of 11596 individuals. Findings showed an overall moderate relationship between dissociation and emotion regulation (r_w = .32; p < .05). The association between dissociation and emotion regulation was the same among clinical samples than non-clinical ones. Furthermore, dissociation showed moderate to large relationships with maladaptive domains of emotion regulation, namely disengagement (r_w = 0.34; p < .01) (i.e., behavioral avoidance, experiential avoidance, thought and emotional suppression) and aversive cognitive perseveration (r_w = 0.38; p < .001) (i.e., rumination, worry and nonacceptance). The analysis did not find significant relationship between dissociation and adaptive domain of emotional regulation (i.e., problem solving, mindfulness).

CONCLUSION

Dissociation in the context of emotion regulation might be viewed as a basic neuro-mental mechanism that automatically contribute to the over-modulation of emotional states through avoidance reactions from internal and external reality. Future longitudinal studies are needed to clarify the causal relationships between dissociation and emotion regulation.

The prevalence of Dissociative Disorders and dissociative experiences in college populations: a meta-analysis of 98 studies

This meta-analysis of 31,905 college students includes 12 studies diagnosing Dissociative Disorders (DD) and 92 studies measuring dissociation with the Dissociative Experiences Scale (DES). Prevalence rates were used to separately test the plausibility of the Trauma Model (TM) and the Fantasy Model (FM) of dissociation. Results show 11.4% of students sampled meet criteria for DD, which is consistent with the prevalence of experiencing multiple (types of) trauma during childhood (12%), but is not consistent with the very low prevalence expected from the role of fantasy-proneness proposed in the FM. DES scores varied significantly across the 16 countries and were not higher in North America, but in countries that were comparatively unsafe. The least well-known DD was the most common, which is inconsistent with the FM which holds that the diagnosed person is enacting a familiar social role. There was no evidence that DES scores had decreased over recent decades, which does not support FM assertions that DD were a fad of the 1990s. Three of the five hypotheses tested provided clear support for the TM and a fourth hypothesis provided partial support for the TM. None of the five hypotheses tested supported the FM. The finding that DD were slightly more common in college populations than the general population did not support predictions of either model. The theoretical perspective of the authors moderated DES scores, although this is unlikely due to experimenter bias as studies led by FM theorists had significantly higher DES scores than those led by TM theorists.

Who wrote that? Automaticity and reduced sense of agency in individuals prone to dissociative absorption

Dissociative absorption (DA) is a tendency to become completely immersed in a stimulus while neglecting to attend to one's surroundings. Theoretically, DA implies automatic functioning in areas that are outside the focus of attention. This study examined whether high absorbers indeed act more automatically, i.e., with decreased meta-consciousness for, and therefore poor memory of, their own actions, along with reduced sense of agency (SoA). High and low absorbers (N = 63) performed three DA-promoting tasks: choice-reaction time (CRT), Tetris, and free writing. Participants were tested on memory of task details and self-reported their state SoA. As hypothesized, trait DA was correlated with impaired autobiographical memory for self-generated writing. However, DA was not related to episodic memory disruptions in externally-generated content tasks (Tetris, CRT). In most tasks, DA was associated with decreased SoA. Absorbers' specific difficulty in identifying self-generated content suggests that their memory failures stem from reduced accessibility to self-actions and intentions.

Psychometric Properties of the Dissociative Subtype of PTSD Scale: Replication and Extension in a Clinical Sample of Trauma-Exposed Veterans

The addition of the dissociative subtype of posttraumatic stress disorder (PTSD) to the DSM-5 has spurred investigation of its genetic, neurobiological, and treatment response correlates. In order to reliably assess the subtype, we developed the Dissociative Subtype of PTSD Scale (DSPS; Wolf et al., 2017), a 15-item index of dissociative features. Our initial investigation of the dichotomous DSPS lifetime items in a veteran epidemiological sample demonstrated its ability to identify the subtype, supported a three-factor measurement structure, distinguished the three subscales from the normal-range trait of absorption, and demonstrated the greater contribution of derealization and depersonalization symptoms relative to other dissociative symptomatology. In this study, we replicated and extended these findings by administering self-report and interview versions of the DSPS, and assessing personality and PTSD in a sample of 209 trauma-exposed veterans (83.73% male, 57.9% with probable current PTSD). Results replicated the three-factor structure using confirmatory factor analysis of current symptom severity interview items, and the identification of the dissociative subtype (via latent profile analysis). Associations with personality supported the discriminant validity of the DSPS and suggested the subtype was marked by tendencies towards odd and unusual cognitive experiences and low positive affect. Receiver operating characteristic curves identified diagnostic cut-points on the DSPS to inform subtype classification, which differed across the interview and self-report versions. Overall, the DSPS performed well in psychometric analyses, and results support the utility of the measure in identifying this important component of posttraumatic psychopathology.

Exploring evidence of a dissociative subtype in PTSD: Baseline symptom structure, etiology, and treatment efficacy for those who dissociate

OBJECTIVE

With the inclusion of a dissociative subtype, recent changes to the DSM-5 diagnosis of posttraumatic stress disorder (PTSD) have emphasized the role of dissociation in the experience and treatment of the disorder. However, there is a lack of research exploring the clinical impact for highly dissociative groups receiving treatment for PTSD. The current study examined the presence and clinical impact of a dissociative subtype in a sample of individuals receiving treatment for chronic PTSD.

METHOD

This study used latent transition analyses (LTA), an expanded form of latent profile analyses (LPA), to examine latent profiles of PTSD and dissociation symptoms before and after treatment for individuals (N = 200) receiving prolonged exposure (PE) or sertraline treatment for chronic PTSD.

RESULTS

The best fitting LTA model was one with a 4-class solution at both pretreatment and posttreatment. There was a latent class at pretreatment with higher levels of dissociative symptoms. However, this class was also marked by higher reexperiencing symptoms, and membership was not predicted by chronic child abuse. Further, although those in the class were less likely to transition to the responder class overall, this was not the case for exposure-based treatment specifically.

CONCLUSION

These findings are not in line with the dissociative-subtype theoretical literature that proposes those who dissociate represent a clinically distinct group that may respond worse to exposure-based treatments for PTSD. (PsycINFO Database Record

Perspectives on the conceptualization of the dissociative subtype of PTSD and implications for treatment

A dissociative subtype of PTSD was added to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to denote a distinct presentation of PTSD marked by symptoms of derealization and depersonalization. The subtype has brought renewed interest in the conceptualization of dissociation in PTSD, and raised questions about its treatment. We review the evidence for two models of PTSD-related dissociative symptoms and the treatment approaches that align with each. We find support for the contributions of biologically-based trait-level factors to dissociation, and suggest that empirically supported treatments for PTSD demonstrate efficacy for patients with the subtype.

Relationship of cognitive function and adjustment difficulties among children and adolescents with dissociative disorder

Background and Aims:

Although it has been suggested that children and adolescents with dissociative disorder have some cognitive deficits, the association of these cognitive impairments with adjustment difficulties has not been evaluated. The present study aimed to assess the relationship between cognitive functioning and adjustment difficulties in children and adolescents with dissociative disorder.

Methods:

This cross-sectional, descriptive assessment was carried out in the outpatient setting of child and adolescent psychiatric service in a tertiary care hospital. Fifty newly diagnosed children and adolescents with dissociative disorder were included. The cognitive functions were assessed by varied neuropsychological tests, and Bell's adjustment inventory was used for assessing various domains of adjustment.

Results:

The mean age of the sample which comprised 40% males was 13.0 (±2.4) years. The mean intelligence quotient (IQ) of the sample was 90.6. Impairment in cognitive test was maximum for verbal working memory followed by sustained attention, visual learning and memory, and verbal retention and recall. Adjustment difficulties were greatest in the domains of self, followed by domains of health, school, and family. Significant association was found between the IQ and adjustment in school; visual learning and memory and adjustments in school and overall adjustment; and sustained attention and adjustment of health.

Conclusions:

Dissociative children have poor cognitive ability which may be related to poor adjustment scores.

An analysis of inhibitory functioning in individuals with chronic posttraumatic stress disorder

Cognitive abnormalities in posttraumatic stress disorder (PTSD) may be a function of underlying inhibitory deficits. Prepulse inhibition (PPI) and attentional blink (AB) are paradigms thought to assess inhibition. Using a sample of 28 individuals with PTSD compared to 20 trauma-exposed and 19 healthy individuals, PPI was examined using white noise that was preceded by a tone, and AB was examined using a presentation of letters in a stream of numbers. Relative to the control group, the PTSD and trauma-exposed groups did not follow the u-shaped pattern in AB, suggesting trauma-exposure and subsequent PTSD are associated with similar impairment in attention. Individuals with PTSD showed reduced PPI compared to trauma-exposed and healthy individuals, suggesting individuals with PTSD exhibit faulty automatic processing. For individuals with PTSD, PTSD severity was associated with a decline in PPI. These findings suggest a general faulty inhibitory mechanism associated with trauma exposure and PTSD.

Relationships between posttraumatic stress disorder (PTSD), dissociation, quality of life, hopelessness, and suicidal ideation among earthquake survivors

Researches have demonstrated that Posttraumatic stress disorder (PTSD) is one of the most common stress reactions in the face of disasters and significantly associated with a broad range of trauma-induced sequelaes including anxiety, depression, suicidality as well as functional impairments. To date, though many aspects of risk factors with respect to the development and maintenance of PTSD have been addressed, mediating role of dissociation has received relatively less attention. In the present study, we examined relations of PTSD with quality of life, hopelessness, suicidal ideation, and mediational effect of pathological dissociation in these connections. 583 subjects most of whom experienced a severe earthquake participated in the study after two years of the disaster. We found that being female, being single, earthquake exposure, and having greater suicidal ideation were significant predictors of PTSD symptom severity. Role-Physical, Bodily-Pain, General Health and Role-Emotional subscales of the SF-36 were inversely associated with PTSD symptom severity. Pathological dissociation significantly mediated the substantial associations between predictors and PTSD symptom clusters. Chronic dissociation appears to put trauma exposed individuals in jeopardy of prolonged posttraumatic reactions by mediating the negative influences of risk factors in the face of experienced earthquake.

Relations between Post-traumatic Stress Disorder, Dissociation and Attention-Deficit/Hyperactivity Disorder among Earthquake Survivors

INTRODUCTION

There is a burgeoning interest in relations between post-traumatic stress disorder (PTSD) and attention-deficit/hyperactivity disorder (ADHD). Although few studies were conducted, weak evidence was found supporting the hypothesis that ADHD may be a risk factor for the development of PTSD. In addition, there is a paucity of research addressing the relations between dissociation and ADHD. In this study, our aim was to examine the relations between PTSD and ADHD combined with the mediating effect of dissociative psychopathology.

METHODS

The participants were 317 undergraduate students, a greater proportion of whom experienced the 2011 Van earthquake (66%). The participants were administered the Posttraumatic Diagnostic Scale, Dissociative Experiences Scale, Adult ADHD Self-Report Scale, Beck Depression Inventory and Beck Anxiety Inventory.

RESULTS

We found that ADHD symptoms and dissociation were significantly associated with PTSD. Considering the multivariate relations between ADHD, PTSD and dissociation, significant associations between PTSD and ADHD resulted from symptom overlaps. However, pathological dissociation mediated the relations between PTSD and ADHD.

CONCLUSION

We concluded that ADHD comorbidity was not a predominant vulnerability factor for the development of post-traumatic stress response but may be an exacerbating factor after the development of PTSD.

Sleep loss increases dissociation and affects memory for emotional stimuli

BACKGROUND AND OBJECTIVES

Because of their dreamlike character, authors have speculated about the role that the sleep-wake cycle plays in dissociative symptoms. We investigated whether sleep loss fuels dissociative symptoms and undermines cognitive efficiency, particularly memory functioning.

METHODS

Fifty-six healthy undergraduate students were randomly assigned to an experimental group (n = 28) and a control group (n = 28). The experimental group was deprived of sleep for 36 h in a sleep laboratory; the control group had a regular night of sleep. Sleepiness, mood, and dissociative symptoms were assessed 6 times in the experimental group (control group: 4 times). Several cognitive tasks were administered.

RESULTS

Sleep deprivation led to an increase in dissociative symptoms, which was mediated by levels of general distress. Feelings of sleepiness preceded an increase of dissociative symptoms and deterioration of mood. Finally, sleep loss also undermined memory of emotional material, especially in highly dissociative individuals.

LIMITATIONS

Limitations included moderate reliability of the mood scale, limited generalizability due to student sample, and a relatively short period of intensive sleep deprivation rather than lengthy but intermittent sleep loss, representative of a clinical population.

CONCLUSIONS

We found that sleep deprivation had significant effects on dissociation, sleepiness, and mood. Specifically, sleepiness and dissociation increased during the night, while mood deteriorated. Our findings stress the importance of sleep deficiencies in the development of dissociative symptoms. They support the view that sleep disruptions fuel distress, but also degrade memory and attentional control. It is against this background that dissociative symptoms may arise.

The Relationships Between Dissociation, Attention, and Memory Dysfunction

INTRODUCTION

Dissociation is a disruption in the integrated functions of consciousness, memory, identity, and perception. Dissociative symptoms include derealization/depersonalization, absorption, and amnesia. These experiences can cause a loss of control over mental processes, including memory and attention. In literature, there is a paucity of research concerning the relationships between dissociation and memory performance. In this study, our aim was to investigate the relationships between dissociative experiences, attention, and memory performance in a non-clinical community sample.

METHODS

In this study, we examined the relationship between dissociation and cognitive dysfunction among 60 healthy volunteers. We administered the Wechsler Memory Scale-Revised, Auditory Verbal Learning Test, Stroop Color Word Interference Test, and Dissociative Experience Scale. Here we examined the relationships between the subtypes of dissociation and memory performance as assessed by neuropsychological tests.

RESULTS

We found that verbal memory was negatively associated with dissociative experiences. Pathological dissociation, particularly amnesia and depersonalization/derealization, was reversely linked to general memory performance and long-term memory. Moreover, low dissociators reported higher scores on verbal memory, general memory performance, and long-term memory but lower scores on recognition than high dissociators.

CONCLUSION

The results of our study suggested that there are significant linkages between dissociative experiences and memory performance.

Investigating the role of executive attentional control to self-harm in a non-clinical cohort with borderline personality features

Self-injurious behavior (or self-harm) is a frequently reported maladaptive behavior in the general population and a key feature of borderline personality disorder (BPD). Poor affect regulation is strongly linked to a propensity to self-harm, is a core component of BPD, and is linked with reduced attentional control abilities. The idea that attentional control difficulties may provide a link between BPD, negative affect and self-harm has yet to be established, however. The present study explored the putative relationship between levels of BPD features, three aspects of attentional/executive control, affect, and self-harm history in a sample of 340 non-clinical participants recruited online from self-harm forums and social networking sites. Analyses showed that self-reported levels of BPD features and attentional focusing predicted self-harm incidence, and high attentional focusing increased the likelihood of a prior self-harm history in those with high BPD features. Ability to shift attention was associated with a reduced likelihood of self-harm, suggesting that good attentional switching ability may provide a protective buffer against self-harm behavior for some individuals. These attentional control differences mediated the association between negative affect and self-harm, but the relationship between BPD and self-harm appears independent.

Night-time experiences and daytime dissociation: a path analysis modeling study

Dissociative symptoms may be the by-products of a labile sleep-wake cycle (Koffel and Watson, 2009a). This may help to explain why dissociation overlaps with fantasy proneness and cognitive failures. Using path analysis, we tested to what extent data gathered in a nonclinical, predominantly female sample (N=139) supported two conceptual models. The first model assumes that unusual sleep experiences increase fantasy proneness and cognitive failures, which in turn encourage trait dissociation and reports of trauma. The second model assumes that trauma leads to dissociative experiences both directly and through its influence on sleep. In this cross-sectional design, the data were reasonably well described by both models. Importantly, in both models, unusual sleep experiences serve as antecedents of trait dissociation. Our analysis underlines the importance of unusual sleep experiences and may inspire treatment intervention focusing on sleep normalization.

Is the dissociative adult suggestible? A test of the trauma and fantasy models of dissociation

Psychologists have long assumed a connection between traumatic experience and psychological dissociation. This hypothesis is referred to as the trauma model of dissociation. In the past decade, a series of papers have been published that question this traditional causal link, proposing an alternative fantasy model of dissociation. In the present research, the relationship among dissociation, suggestibility, and fantasy proneness was examined. Suggestibility was measured through the Gudjonsson Scale of Interrogative Suggestibility (GSS) as well as an autobiographically based version of this measure based on the events of September 11, 2001. Consistent with prior research and with the trauma model, dissociation correlated positively with trauma severity (r = .32, p < .01) and fantasy proneness (r = .60, p < .01). Inconsistent with the fantasy model, dissociation did not correlate with the neutral form of the GSS and correlated negatively (r = -.24, p < .05) with the trauma-focused form of this suggestibility measure. Although some participants did become quite emotional during the procedure, the risk/benefit ratio was perceived by almost all participants to be positive, with more reactive individuals evaluating the procedure more positively. The results consistently support the trauma model of dissociation and fail to support the fantasy model of dissociation.

Post-traumatic stress disorder, dissociation, and neuropsychological performance in Latina victims of childhood sexual abuse

This study compared the memory, attention/concentration, and executive functioning of 12 women with histories of child sexual abuse with a control group of 12 women without childhood abuse. Participants completed a neuropsychological test battery and various instruments assessing post-traumatic stress disorder and dissociation. The child sexual abuse group had lower performance than the control group on long- and short-term visual and verbal memory and presented more limited performance on executive functioning tasks. Functioning in these areas showed a negative correlation with post-traumatic stress disorder and dissociative symptoms. These findings suggest that child sexual abuse is associated with memory and executive functioning deficits and supports the idea that people with trauma histories and increased post-traumatic stress disorder and dissociation symptoms may have alterations in neuropsychological functioning.

Fragmented Sleep, Fragmented Mind

In psychopathology, dissociation typically refers to a disturbance in the normal integration of thoughts, feelings, and experiences into consciousness and memory. In this article, we review the literature on how sleep disturbances relate to dissociative symptoms and memory failure. We contend that this body of research offers a fresh perspective on dissociation. Specifically, we argue that dissociative symptoms are associated with a labile sleep–wake cycle, in which dreamlike mentation invades the waking state, produces memory failures, and fuels dissociative experiences. The research domain of sleep and dissociation can accommodate the dominant idea in the clinical literature that trauma is the distal cause of dissociation, and it holds substantial promise to inspire new treatments for dissociative symptoms (e.g., interventions that focus on normalization of the sleep-wake cycle). We conclude with worthwhile paths for further investigations and suggest that the sleep–dissociation approach may help reconcile competing interpretations of dissociative symptoms.

Unintentional memory inhibition is weakened in non-clinical dissociators

Although participants with dissociation proneness showed inefficient cognitive inhibition, whether and under what stimulus-task contexts dissociators show inefficient memory inhibition remains inconclusive. This study investigated the relationship between trait dissociation and basic operation of memory control using a non-clinical sample. To reduce the involvement of strategic control and the influence of emotionality, the retrieval-practice paradigm was adopted to examine unintentional memory inhibition of neutral materials. Both the low- and middle-dissociation groups showed the forgetting effect, resulting from suppressing competing memories while retrieving a target. In contrast, the high-dissociation group did not show the forgetting effect although their performance in the baseline condition and in recalling practiced items was comparable to the other two groups. High dissociation proneness is linked with weakened memory inhibition that may cause diverse memory problems in clinical patients.

Alexithymia, absorption, and cognitive failures in depersonalization disorder: a comparison to posttraumatic stress disorder and healthy volunteers

Alexithymia, absorption, and cognitive failures are traits that have been implicated in dissociative psychopathology. Forty-six participants with depersonalization disorder (DPD), 21 with posttraumatic stress disorder, and 35 healthy controls completed measures of dissociation, alexithymia, absorption, cognitive failures, and childhood trauma. The DPD and posttraumatic stress disorder groups had significantly and comparably elevated absorption and cognitive failures scores. Only the DPD group had significantly elevated alexithymia scores, specifically in "difficulty identifying feelings." Regression analyses revealed that "alexithymia-difficulty identifying feelings" was predictive of both DPD diagnosis and depersonalization scores. In contrast, amnesia scores were predicted by childhood trauma and absorption. In conclusion, the link between depersonalization and alexithymia appeared to be specific rather than broadly related to early trauma or to trauma-spectrum psychopathology.

Pathological dissociation and neuropsychological functioning in borderline personality disorder

OBJECTIVE

Transient, stress-related severe dissociative symptoms or paranoid ideation is one of the criteria defining the borderline personality disorder (BPD). Examinations of the neuropsychological correlates of BPD reveal various findings. The purpose of this study was to investigate the association between dissociation and neuropsychological functioning in patients with BPD.

METHOD

The performance on an extensive neuropsychological battery of patients with BPD with (n=10) and without (n=20) pathological dissociation was compared with that of healthy controls (n=30).

RESULTS

Patients with pathological dissociation were found to have reduced functioning on every neuropsychological domain when compared with healthy controls. Patients without pathological dissociation were found to have reduced executive functioning, but no other differences were found.

CONCLUSION

Pathological dissociation is a clinical variable that differentiates patients with BPD with regard to cognitive functioning.

Neuropsychological characteristics of highly dissociative healthy individuals

OBJECTIVE

Dissociative disorders are characterized by disturbances in several neuropsychological domains, especially attention, memory, and consciousness. As a tendency to dissociate can also be observed in healthy individuals, and may be a risk factor for the development of dissociative disorders and posttraumatic stress disorder (PTSD), we were interested in the neuropsychological characteristics of these participants.

METHOD

We examined attention, memory, and executive control functions in 17 high and 17 low dissociators without any psychiatric or neurological disorder and without prior experiences of trauma.

RESULTS

High dissociators showed relative performance deficiencies in tasks of memory for associative, context-dependent verbal material, visuospatial working memory, and executive control functions in terms of a heightened perseveration tendency and false positive errors.

CONCLUSION

These cognitive deficits are consistent with models of dissociative disorders and dissociation in PTSD assuming a hippocampal and prefrontal dysfunction as a core factor. Mild cognitive impairments in otherwise healthy high dissociators may constitute a risk factor for the development of later PTSD or dissociative disorders.

Cognitive functioning in depersonalization disorder

Depersonalization disorder (DPD) is a dissociative disorder characterized by a subjective sense of unreality and detachment, and has been associated with deficits in perception and short-term memory. In this study, 21 DPD and 17 healthy comparison participants free of psychiatric disorders were administered a comprehensive neuropsychologic battery. The groups did not differ in full-scale, verbal, and performance IQ (Wechsler Adult Intelligence Scale), in working memory (Paced Auditory Serial Addition Test), or in selective attention (Digit Span with Distracters). The DPD group performed significantly worse on immediate visual and verbal recall (Wechsler Memory Scale, Revised), but not on delayed recall. Dissociation severity was significantly correlated with processing slowness and distractibility. We conclude that DPD is associated with cognitive disruptions in early perceptual and attentional processes.

The relationship between executive functioning and dissociation

Although dissociation by definition affects cognition, few studies have used neuropsychological measures to examine dissociative phenomena. This study compared 33 high and 32 low dissociators based on the Dissociative Experiences Scale, on self-report and neuropsychological measures of executive function, including the Dysexecutive Questionnaire, Iowa Gambling Task, Operation Span task, and Wisconsin Card Sorting Test-64. High dissociators endorsed significantly more executive difficulties than did low dissociators, but these difficulties were not related to their performance on neuropsychological measures. Results suggest that dissociative individuals' perceptions of executive impairments may be divorced from objective deficits, revealing an important process underlying the clinical manifestations of dissociation.

Why dissociation and schizotypy overlap: the joint influence of fantasy proneness, cognitive failures, and childhood trauma

A number of studies have noted that dissociative symptoms (e.g., feelings of derealization, depersonalization, memory complaints, absorption) overlap with the tendency to report psychotic-like experiences (i.e., schizotypy). The question arises as to what may account for the shared variance between dissociation and schizotypy. The present study investigated whether fantasy proneness, cognitive failures, and childhood trauma may jointly explain the dissociation-schizotypy link. To this end, we administered the Dissociative Experiences Scale, the Schizotypal Personality Scale, the Creative Experiences Questionnaire, the Cognitive Failures Questionnaire, and the Childhood Trauma Questionnaire to a sample of undergraduates (N = 185). Fantasy proneness, cognitive failures, and childhood trauma together explained substantial part (58%) of the dissociation-schizotypy link. The present study succeeded in explaining a considerate part of the shared variance between dissociation and schizotypy.

The random number generation task: psychometric properties and normative data of an executive function task in a mixed sample

We investigated the psychometric properties of the random number generation (RNG) task in four studies using a mixed sample of young adults (n = 306), middle-aged adults (n = 40), and patients diagnosed with schizophrenia (n = 26). Data in study 1 were best accounted for by a three-factor solution representing inhibition of stereotypical schemas (seriation), output inhibition (repetition), and monitoring of previous output (cycling). Modest test-retest correlations were found, with the seriation factor showing acceptable stability across time (study 2). In study 3, RNG task performance was related to scores on concurrent neurocognitive tasks to establish construct validity. RNG scores correlated with healthy controls' performance on the Stroop color-word test and patients diagnosed with schizophrenia with executive dysfunctions. Patients diagnosed with schizophrenia performed poorer on the seriation factor of the RNG than healthy control participants (study 4). Our results indicate that the RNG task has modest to acceptable psychometric properties. It primarily taps executive subfunctions (i.e., inhibition, updating, and monitoring), which are affected by psychopathological or neurological deficits.

Dissociation, memory commission errors, and heightened autonomic reactivity

If dissociative symptoms are manifestations of a psychological defense mechanism, one would expect people who have such symptoms to react with lower levels of physiological arousal and with memory omissions to emotionally provocative material. The current study tested this assumption in a sample of undergraduates. Sixty-two undergraduate students viewed a highly emotional video fragment. Pearson's product-moment correlations were calculated between dissociation (as indexed by the Dissociative Experiences Scale, DES) and all dependent measures. High dissociators exhibited elevated skin conductance responses (SCRs) to the fragment. Memory for the video fragment was then tested. While omission errors were unrelated to dissociation, high dissociators exhibited a tendency to produce commission errors. This could not be explained by a reduced working memory capacity. However, fantasy proneness was found related to high dissociators' commission errors. Thus, it seems that a pattern of heightened emotional reactivity and commission errors is typical for people with elevated dissociation scores. This pattern is difficult to reconcile with the defensive function ascribed to dissociation.

Reality monitoring and motor memory in checking-prone individuals

Studies concerning reality monitoring and motor memory abilities in checkers have provided mixed results. The aim of this study was to re-examine this question by asking 75 undergraduate students to perform, watch the experimenter perform, imagine themselves performing, imagine the experimenter performing, or verbally repeat different daily actions. Two groups were created (checking-prone and nonchecking-prone subjects) based on participants' checking subscores on the revised version of the Obsessive-Compulsive Inventory. First, results suggested that checking-prone subjects have a poorer motor memory than nonchecking-prone participants. Second, our data indicated that checking-prone participants confused actions they had performed with actions the experimenter had performed more often than nonchecking-prone participants. In other words, checking-prone participants remembered events from an observer's viewpoint. Finally, our findings suggest that dissociation could be a mediating variable between some of the reality monitoring abilities and checking.

Dissociation, resting EEG, and subjective sleep experiences in undergraduates

In this study, we explored whether individual differences in dissociation are related to certain resting electroencephalographic (EEG) parameters. Baseline EEG with eyes open and closed was recorded in an undergraduate sample (N = 67). Cortical power in the alpha range was inversely related to dissociative symptoms as measured by the Dissociative Experiences Scale, while both delta and theta power where positively related to dissociation. However, sleep experiences, as indexed with the Iowa Sleep Experiences Survey, were unrelated to resting EEG characteristics. We propose that suppression in the alpha band and raised levels of theta activity, which are typical for high dissociators, might help to explain why dissociative symptoms are accompanied by attentional and memory deficits.