Dissociation and memory fragmentation: experimental effects on meta-memory but not on actual memory performance

The role of dissociation-related beliefs about memory in trauma-focused treatment

OBJECTIVE

Dysfunctional cognitions play a central role in the development of post-traumatic stress disorder (PTSD). However the role of specific dissociation-related beliefs about memory has not been previously investigated. This study aimed to investigate the role of dissociation-related beliefs about memory in trauma-focused treatment. It was hypothesized that patients with the dissociative subtype of PTSD would show higher levels of dissociation-related beliefs, dissociation-related beliefs about memory would decrease after trauma-focused treatment, and higher pre-treatment dissociation-related beliefs would be associated with fewer changes in PTSD symptoms.

METHOD

Post-traumatic symptoms, dissociative symptoms, and dissociation-related beliefs about memory were assessed in a sample of patients diagnosed with PTSD (n = 111) or the dissociative subtype of PTSD (n = 61). They underwent intensive trauma-focused treatment consisting of four or eight consecutive treatment days. On each treatment day, patients received 90 min of individual prolonged exposure (PE) in the morning and 90 min of individual eye movement desensitization and reprocessing (EMDR) therapy in the afternoon. The relationship between dissociation-related beliefs about memory and the effects of trauma-focused treatment was investigated.

RESULTS

Dissociation-related beliefs about memory were significantly associated with PTSD and its dissociative symptoms. In addition, consistent with our hypothesis, patients with the dissociative subtype of PTSD scored significantly higher on dissociation-related beliefs about memory pre-treatment than those without the dissociative subtype. Additionally, the severity of these beliefs decreased significantly after trauma-related treatment. Contrary to our hypothesis, elevated dissociation-related beliefs did not negatively influence treatment outcome.

CONCLUSION

The results of the current study suggest that dissociation-related beliefs do not influence the outcome of trauma-focused treatment, and that trauma-focused treatment does not need to be altered specifically for patients experiencing more dissociation-related beliefs about memory because these beliefs decrease in association with treatment.

Challenging memories reduces intrusive memories and the memory amplification effect

This study scrutinizes the influence of attenuating beliefs about the veracity of traumatic experiences on the manifestation of intrusive recollections and the memory amplification effect. Participants were exposed to distress-inducing visual stimuli, subsequently rating their emotional status pre and post exposure. They engaged in a recognition task, identifying scenarios within the stimuli. Participants' recall was contested, casting doubt about the occurrence of certain scenes. Subsequently, they maintained a daily log of intrusive memories over a week. A second session reiterated the same process. This method effectively diminished the certainty in the participants' traumatic memories. Scenes whose occurrence was contested demonstrated a significant decline in both intrusive memories and memory amplification when juxtaposed with uncontested ones. Interestingly, no significant correlation emerged between the diminished belief in traumatic incidents and reductions in intrusive memory or memory amplification. Thus, this study advocates that interrogating the veracity of traumatic recollections can mitigate the prevalence of intrusive memories and the memory amplification effect, suggesting a novel potential therapeutic approach for trauma-related disorders.

Association between negatively perceived parenting attitudes and dissociation: a cross-sectional study on the general population in Japan

Objectives

Many studies have reported that early traumatic experiences, mainly abuse, are associated with forming dangerous attachments and a contributing factor to dissociation. On the other hand, other studies have investigated the association of non-abusive nurturing and attachment styles with dissociation. The aim of this study is to determine the frequency of dissociative experiences in the general Japanese population and investigate the effects of "overprotection" and "lack of care" as nurturing styles and "abandonment anxiety" and "avoidance of intimacy" as attachment styles on dissociation.

Methods

A total of 1,042 residents aged 18 to 69 years were administered with the Dissociative Experiences Scale (DES), the Japanese version of the WHO-5 Well-Being Index (WHO-5-J), the Parental Bonding Instrument (PBI), and the Experiences in Close Relationships Inventory-the-generalized-other-version (ECR-GO). Hierarchical multiple regression analyses on the effects of "overprotection" and "care" as nurturing attitudes "abandonment anxiety" and "avoidance of intimacy" as attachment styles on dissociation (DES-NDI and DES-T) were conducted.

Results

Based on the findings of this study, "care" and "overprotection" as nurturing attitudes were shown to be a contributing factor to dissociation (DES-NDI and DES-T). "Avoidance of intimacy" as an attachment style was shown to contribute to pathological dissociation. On the other hand, the influence of attachment style on the relationship between nurturing style and dissociation was not determined.

Discussion

This study provided essential data on the distribution of dissociative experiences in the general Japanese population. It was indicated that nurturing style, particularly overprotection, may be linked to nonfunctional stress coping and interpersonal anxiety and could be a contributing factor to mental disorders, including dissociation. Furthermore, considering that the effect of nurturing styles on dissociation does not vary with attachment styles, the effect of nurturing styles on dissociation may be more profound.

Peritraumatic dissociation revisited: associations with autonomic activation, facial movements, staring, and intrusion formation

BACKGROUND

Peritraumatic dissociation is purported to emerge together with attenuated autonomic arousal, immobility, and staring. However, empirical evidence is scarce and heterogeneous. Moreover, it is still a matter of debate whether these responses predict intrusion formation.

OBJECTIVE

The present trauma-analogue study examined associations between peritraumatic dissociation, autonomic activation, facial movements, staring, and intrusion formation.

METHOD

Seventy-one healthy women watched a highly aversive film, while autonomic activation (heart rate, respiratory sinus arrhythmia, skin conductance level), facial movements (temporal variations in corrugator electromyography), and staring (fixation duration, tracklength) were assessed. Afterwards, participants rated the intensity of dissociation during film viewing and reported intrusions and associated distress in a smartphone application for 24 hours.

RESULTS

Peritraumatic dissociation was linked to higher autonomic arousal (higher heart rate and, on a trend-level, lower respiratory sinus arrhythmia), increased facial movements, and staring (lower tracklength). Peritraumatic dissociation, higher autonomic arousal (higher heart rate and lower respiratory sinus arrhythmia), staring (higher fixation duration), and, on a trend-level, more facial movements were linked to higher intrusion load (number x distress of intrusions) and together explained 59% of variance. Skin conductance level was neither linked to peritraumatic dissociation nor intrusion load.

CONCLUSIONS

Our results suggest that, at low-dissociation-levels observed in trauma-analogue studies, peritraumatic dissociation may occur together with heightened autonomic arousal and facial movements, indexing increased negative affect. Staring might, irrespectively of dissociation-levels, serve as objective marker for dissociation. Together, peritraumatic dissociation and its psychophysiological correlates might set the stage for later intrusion formation.

Differential Effects of Poor Recall and Memory Disjointedness on Trauma Symptoms

Clinical theories of posttraumatic stress disorder (PTSD) suggest that trauma memories are disorganized. In the present study, we examined how trauma-film exposure affects two aspects of memory disorganization, poor memory recall and memory disjointedness, and their relationship to PTSD-like symptoms. In Session 1, 90 healthy participants were exposed to a trauma (n = 60) or a neutral film (n = 30). Cognitive processing styles, memory characteristics, and intrusive memories of the film were assessed. The trauma-film group reported greater memory disjointedness of the worst moments of the film but better memory recall of the film than the neutral-film group. In the trauma-film group, cognitive processing and memory disjointedness were related to intrusive memories and PTSD-like symptoms in the week after film exposure. Memory disjointedness but not poor memory recall mediated the relationship between cognitive processing and intrusions. The findings suggest that different aspects of memory disorganization need to be distinguished to explain PTSD symptoms.

The effects of state anxiety on analogue peritraumatic encoding and event memory: introducing the stressful event segmentation paradigm

Cognitive theories of PTSD argue that poor recall of trauma memories results from a stress-induced shift toward perceptual processing during encoding. The present study assessed the extent to which self-reported state anxiety affects event segmentation and its subsequent impact on memory performance (recall and recognition). Event segmentation is the cognitive process of condensing continuous streams of spatiotemporal information into discrete elements. In this study, undergraduates without PTSD used a computer programme to segment a stressful film and a non-stressful film and then they completed memory tasks for each film. For the stressful film, low memory performance was associated with high segmentation performance. A meditational analysis revealed high segmentation performance mediated a negative relationship between state anxiety and memory performance. Additionally, ad-hoc analyses suggest perceptual processing primarily drives segmentation of the stressful film and conceptual processing primarily drives segmentation of the non-stressful film.

Neurological soft signs, dissociation and alexithymia in patients with obsessive-compulsive disorder (OCD) and healthy subjects

A body of evidence has supported that patients with obsessive-compulsive disorder (OCD) have increased rates of various neurological soft signs (NSS) compared to controls. Various lines of research has documented robust relationships between OCD and dissociative symptomatology. The study aimed to examine the associations between obsessive-compulsive symptoms, dissociative experiences alexithymia, and NSS. The study included thirty OCD patients and thirty healthy controls, matched for age, marital status, education, and income. The Neurological Evaluation Scale (NES), Padua Inventory-Revised (PI-R), Dissociative Experiences Scale (DES) and Toronto Alexithymia Scale (TAS-20) were administered. In comparison to healthy controls, patients with OCD had difficulty sequencing for complex motor acts and greater absorption/ imaginative involvement. Using latent class analysis, the study sample was classified into two homogenous subsets as mild NSS (n = 45) and severe NSS (n = 15). Majority of the participants who were grouped into severe NSS latent class were OCD patient (n = 14, 93.3%). Furthermore, those with severe NSS reported greater levels of alexithymia and more severe obsessive-compulsive symptoms, particularly precision. We concluded that relationships between OCD severity and NSS appear to be of crucial importance. Our data along with accumulated evidence suggest that OCD associated with pronounced NSS may represent a specific subtype of the disorder.

Binding Temporal Context in Memory: Impact of Emotional Arousal as a Function of State Anxiety and State Dissociation

Encoding of stressful experiences plays an important role in the development of posttraumatic stress disorder. A crucial aspect of memory encoding is binding: the "gluing" of the temporal and spatial elements of an episode into a cohesive unit. This study investigated the effect of emotional arousal on temporal binding and examined whether temporal binding varied as a function of state anxiety and/or state dissociation. Participants saw picture sequences that varied in arousal and valence. After each sequence, participants were presented with all the pictures simultaneously and had to sort the pictures in the original order. Temporal context binding was indexed by sorting accuracy. Binding was generally lower for high than low arousing pictures. Reduced binding of arousing material was specifically pronounced in participants with high state anxiety, whereas it seemed independent of state dissociation. These findings point to the relevance of impaired temporal binding as a component of aberrant memory encoding in stressful situations.

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.

Expressive inhibition in response to stress: implications for emotional processing following trauma

Expressive inhibition--the willful restriction of expressed emotion--is documented in individuals reporting trauma-related distress, but its impact on global affective functioning remains unclear. Theoretical models propose that chronic activation of negative emotion and deliberate restriction of affect operate synergistically to produce trauma-related emotional deficits. The current project examined the impact of these factors on subjective experience and physiological activation following exposure to an analog trauma. University students (N=192; Mage=20, 57% female, 42% White/Non-Hispanic) viewed a graphic film depicting scenes of a televised suicide. Participants then viewed either a sadness- or humor-eliciting film under instructions to inhibit [nsadness=45, nhumor=52] or naturally express emotion [nsadness=48, nhumor=47]. Expressive inhibition was associated with restricted amusement specifically among participants viewing the humor film. Inhibition also produced attenuated sympathetic and parasympathetic recovery, irrespective of film assignment. Evidence of disruptions in emotional processing supports models identifying inhibition as a possible mechanism in post-trauma affect dysregulation.

Unconscious thought reduces intrusion development: a replication and extension

BACKGROUND AND OBJECTIVES

Intrusive images after a traumatic event, a hallmark feature of post-traumatic stress disorder, are suggested to develop because the trauma memory is disorganized and not integrated into autobiographical memory. Unconscious Thought Theory predicts that information can be conceptually organized after a period of unconscious thought (UT), more so than after conscious thought (CT). We aimed to test the hypothesis that UT decreases intrusions and increases conceptual organization in memory.

METHODS

Participants were shown a stressful film and were required to perform an UT task, a CT task, or a distraction task. Intrusions of the film, intrusion qualities, and sequence memory were measured afterwards.

RESULTS

We confirmed our hypothesis that UT (versus CT or mere distraction) leads to fewer intrusions, thereby replicating earlier research. Contrary to prediction, we found no difference between the conditions on sequence memory. In addition, conscious thought appeared to increase intrusion nowness and arousal.

LIMITATIONS

The analogue design and healthy participant sample prevent from generalizing results to other populations. Intrusion frequency and qualities were assessed immediately after the film thereby prohibiting us from drawing conclusions about any long-term effects.

CONCLUSIONS

Engaging in unconscious thought after a stressful film can reduce intrusion frequency. This has potential implications for clinical interventions to prevent initial stress symptoms. The underlying mechanism remains unclear for now and provides an avenue for future research.

Null's the word: a comparison of memory quality for intensely negative and positive events

Research comparing memories of traumatic and positive events has produced inconsistent results. Complicating the issue, researchers employ a variety of measures (e.g., narrative or questionnaire) that make comparison across studies difficult. Further, this research has been criticised for lacking adequate statistical controls (Sotgiu & Mormont, 2008). Our study employed both narrative and questionnaire methodologies and compared memories for highly negative and positive events while controlling for retention interval, intensity of the event, and word count in the narrative measures. A total of 108 racially diverse college undergraduates wrote narratives and completed the Memory Characteristics Questionnaire about the most negative and the most positive event they had experienced, and memories were assessed for narrative coherence, language indicative of cognition, insight and sensory experience, subjective ratings of clarity, sensory detail, contextual detail, temporal detail, and the inclusion of thoughts and feelings. Results indicate no differences between memories for highly negative and positive events when retention interval and emotional intensity are controlled.

False memories for missing aspects of traumatic events

Can people come to remember an event as being more traumatic than they initially experienced? Participants watched a highly structured and emotionally disturbing film depicting a car accident in which five people, including a baby, are killed. We broke the film down into a series of short clips; some of which we removed. Later, we tested participants' memory for what they had and had not seen. While participants were highly accurate identifying what they had and definitely had not seen, they also falsely claimed to have seen 26% of the missing clips, clips that fitted with the film but were removed before screening. Moreover, participants were particularly likely to recall the missing clips that were considered to be the most critical and traumatic. Importantly, they did so with high confidence. We discuss both intentional and unintentional recall mechanisms that may promote the observed memory distortion.

The prediction of intrusions following an analogue traumatic event: peritraumatic cognitive processes and anxiety-focused rumination versus rumination in response to intrusions

Intrusions are often considered the hallmark of posttraumatic stress disorder (PTSD). Despite this, relatively little is known about factors that give rise to intrusions. Cognitive models of PTSD highlight the importance of pre-existing cognitive vulnerabilities, cognitive processing and anxiety during a traumatic event, as well as negative responses to trauma sequelae. However, few studies have examined multiple forms of peritraumatic processes, and rumination in response to trauma intrusions using analogue trauma tasks, and none have examined whether broader anxious ruminative processes contribute to intrusion development. In addition, little work has investigated the role of post-state anxiety in intrusions, and anxiety may be related to both peritraumatic processing and rumination. The current study employed a distressing film paradigm to examine key tenets of cognitive models of PTSD. Ninety-one female university students completed measures of anxiety, rumination in response to anxious symptoms, peritraumatic dissociation, data driven processing, lack of self referent processing, intrusions, and rumination in response to intrusions of the distressing film. Results revealed that peritraumatic dissociation, data driven processing, and self referent processing were associated with intrusion development, with lack of self referent processing being a strong predictor of intrusion development. Post-state anxiety and rumination in response to intrusions also predicted intrusion development. Discussion focuses on implications of cognitive processes and anxiety in theories of intrusion development.

Dissociation and memory fragmentation in post-traumatic stress disorder: an evaluation of the dissociative encoding hypothesis

Several prominent theories of post-traumatic stress disorder (PTSD) posit that peritraumatic dissociation results in insufficient encoding of the trauma memory and that persistent dissociation prevents memory elaboration, resulting in memory fragmentation and PTSD. In this review we summarise the empirical literature on peritraumatic and trait dissociation and trauma narrative fragmentation as measured by meta-memory and rater/objective coding. Across 16 studies to date, the association between dissociation and fragmentation was most prominent when examining peritraumatic dissociation and patient's own ratings of memory fragmentation. This relationship did not hold when examining trait dissociation or rater-coded or computer-generated measures of fragmentation. Thus initial evidence points more towards a strong self-reported association between constructs that is not supported on more objective fragmentation coding. Measurement overlap, construct ambiguity, and exclusion of potential confounds may underlie lack of a strong association between dissociation and objective-rated fragmentation.

Integration and organization of trauma memories and posttraumatic symptoms

To examine the connection between trauma memory integration in personal memory, memory organization, and posttraumatic symptom severity, 47 trauma-exposed adults undertook an event-cuing task for their trauma memory and for a memorable nontraumatic negative event. Measures of integration provided by self-endorsement, rated by naïve judges, or calculated from the language of the memories, did not significantly predict posttraumatic stress disorder symptom severity after adjusting for age, time since the event, anxiety when disclosing, familiarity of the memory, and integration of nontrauma memory. Less use of casual connectives in the trauma memory narrative was associated with higher trauma-related avoidance (r = .33; p = .03), whereas self-rating of the trauma memory as disorganized was associated with higher overall symptom severity (r = .42; p = .006).

Combining clinical studies and analogue experiments to investigate cognitive mechanisms in posttraumatic stress disorder

Research into cognitive mechanisms in posttraumatic stress disorder (PTSD) typically comprises two types of studies. The first group of studies is conducted with survivors of traumatic events and assesses the association between PTSD and cognitive variables with questionnaires and/or information processing paradigms. In the second group of studies, healthy non-traumatized individuals are exposed to an analogue stressor (e.g., a stressful film) and cognitive variables of interest are usually experimentally manipulated to investigate their effects on analogue PTSD symptoms. This review illustrates how studies of trauma survivors and analogue studies with non-traumatized populations can be usefully combined. Two examples for this approach are presented: (1) research into the role of perceptual priming for trauma-related stimuli and (2) research into trauma-related rumination. The advantages and limitations of both types of studies are discussed and it is argued that a combination of both approaches is needed to investigate cognitive mechanisms in PTSD.

The nature of trauma memories in acute stress disorder in children and adolescents

BACKGROUND

There is increasing theoretical, clinical and research evidence for the role of trauma memory in the aetiology of acute pathological stress responses in adults. However, research into the phenomenology of trauma memories in young people is currently scarce.

METHODS

This study compared the nature of trauma narratives to narratives of unpleasant non-traumatic events in young people (aged 8-17) who sought emergency medical attention following an assault or road traffic accident. Data were collected within 2-4 weeks of the index event. Symptom severity was assessed by child self-report and face-to-face diagnostic interviews. Comparisons of narrative indices were made between those children with acute stress disorder (ASD) and those without ASD.

RESULTS

Among participants (n = 50), those with ASD (38%) had significantly elevated levels of disorganisation in their trauma narrative, compared both to trauma-exposed controls and to their unpleasant comparative narrative. This effect was not accounted for by age. Regardless of ASD diagnostic status, trauma narratives had significantly higher sensory content and significantly lower positive emotion content compared to the unpleasant comparative narrative. These effects were not significant when age was included as a covariate. Acute symptom severity was significantly predicted by the level of disorganisation in the trauma narrative and the child's cognitive appraisals of the event.

CONCLUSIONS

These data provide the first empirical evidence that disorganisation is not only directly linked to symptom severity, but also specific to the trauma memory. In addition, it provides support for the adaptation of adult cognitive models to acute pathological stress reactions in children and adolescents.

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.

A transdiagnostic comparison of trauma and panic memories in PTSD, panic disorder, and healthy controls

Inadequate processing of trauma information is considered to lead to particularly vivid recollections and disorganized memories of the trauma. Although trauma memories have mainly been investigated in PTSD, memories in other psychiatric disorders may actually share some characteristics. This may particularly be true for patients with panic disorder with agoraphobia (PDA) as a first panic attack resembles trauma. To test this hypothesis, PTSD trauma memories (n=59) were compared with PDA panic memories (n=58), and trauma memories of healthy trauma victims (n=135) on self-reported re-experiencing and disorganization. PTSD trauma memories had more re-experiencing elements than memories of the other two groups, although PDA memories had more re-experiencing elements than the controls' trauma memories. Relative to the controls, PTSD and PDA memories were disorganized. Peritraumatic dissociation and current memory-associated dissociation were also high in PTSD and PDA patients compared to the controls. Implications of these results are discussed.

A comparison of memory for homicide, non-homicidal violence, and positive life experiences

Defendants commonly claim amnesia for their criminal actions especially in cases involving extreme violence. While some claims are malingered or result from physiological factors, other cases may represent genuine partial or complete amnesia resulting from the psychological distress and/or extreme emotion associated with the perpetration of the crime. Fifty Canadian homicide offenders described their memories of their homicide, a non-homicide violent offense, and their most positive adulthood life experience. Self-reported and objective measures of memories for these events revealed that homicides were recalled with the greatest level of detail and sensory information. Although dissociative tendencies were associated with a self-reported memory loss, objective measures of memory quality did not reflect this perceived impairment, suggesting a failure of meta-memory. Recollections of positive life events were superior to those of non-homicidal violence, possibly due to greater impact and meaning attached to such experiences. Findings suggest that memory for homicide typically is enhanced by the powerful emotion associated with its perpetration.

Acute effects of alcohol on the development of intrusive memories

RATIONALE

Post-traumatic stress disorder is characterised by repeated intrusive imagery of the traumatic event. Despite alcohol's impairing effect on memory and frequent involvement in real-life trauma, virtually nothing is known of the interaction between alcohol and trauma memory.

OBJECTIVE

We aimed to investigate the acute alcohol effects on spontaneous memories following a trauma film as well as explicit memory for the film.

METHODS

Utilising an independent-group double-blind design, 48 healthy volunteers were randomly allocated to receive alcohol of 0.4 or 0.8 g/kg or a matched placebo drink. A stressful film was viewed post-drink. Skin conductance was monitored throughout and mood and dissociative symptoms were indexed. Volunteers recorded their spontaneous memories of the film daily in an online diary over the following week. Their explicit memory for both gist and details of the film was tested on day 7.

RESULTS

Intriguingly, an inverted 'U' alcohol dose-response was observed on intrusive memories with a low dose of alcohol increasing memory intrusions while a high dose decreased intrusions. In contrast, explicit memory performance after 7 days showed a linear dose-response effect of alcohol with both recall and recognition decreasing as dose increased.

CONCLUSIONS

These findings highlight a striking differential pattern of alcohol's effects on spontaneous memories as compared with explicit memories. Alcohol's effect on spontaneous memories may reflect a dose-dependent impairment of two separate memory systems integral to the processing of different aspects of a traumatic event.

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.

The Effects of Conceptual Processing Versus Suppression on Analogue PTSD Symptoms after a Distressing Film

Background:Researchers have begun to scrutinize the assumption that active processing in response to a traumatic event is beneficial whereas avoidance of thoughts, emotions and reminders about the traumatic event is detrimental. Indications that avoidance is not always detrimental come from studies on grief and debriefing.Aims:In an analogue experimental study, the hypothesis was tested that conceptually-driven processing immediately after a distressing film is more successful in reducing analogue PTSD symptoms than suppression of thoughts and images related to the film.Method:Ninety students watched a distressing film after which they were instructed to either elaborate on the meaning of the film (conceptual processing) (n= 31), suppress all thoughts and images of the film by performing a task (n= 29), or were given no instruction (n= 30). Four hours later, analogue PTSD symptoms were assessed.Results:The results showed that conceptually-driven processing does not result in fewer analogue PTSD symptoms than suppression.Conclusions:It is speculated that suppression may only be dysfunctional when individuals interpret their symptoms negatively or when suppression is believed to be dysfunctional.

The influence of data-driven versus conceptually-driven processing on the development of PTSD-like symptoms

Ehlers and Clark [(2000). A cognitive model of posttraumatic stress disorder. Behaviour Research and Therapy, 38, 319-345] propose that a predominance of data-driven processing during the trauma predicts subsequent PTSD. We wondered whether, apart from data-driven encoding, sustained data-driven processing after the trauma is also crucial for the development of PTSD. Both hypotheses were tested in two analogue experiments. Experiment 1 demonstrated that relative to conceptually-driven processing (n=20), data-driven processing after the film (n=14), resulted in more intrusions. Experiment 2 demonstrated that relative to the neutral condition (n=24) and the data-driven encoding condition (n=24), conceptual encoding (n=25) reduced suppression of intrusions and a trend emerged for memory fragmentation. The difference between the two encoding styles was due to the beneficial effect of induced conceptual encoding and not to the detrimental effect of data-driven encoding. The data support the viability of the distinction between data-driven/conceptually-driven processing for the understanding of the development of PTSD.

The effect of cognitive load and hyperarousal on negative intrusive memories

Clinical theories of post-traumatic stress suggest that encoding processes at the time of a trauma are critical in determining whether intrusive memories will develop. Potential mechanisms that might influence the development of intrusive memories were studied, as was objective memory performance. In an analogue design, 65 participants were randomised to three conditions (cognitive load, hyperventilation, and control), and then watched a film of traumatic content. Intrusive memories were recorded during the experimental phase and at 1-week follow-up. Support was found for the prediction that verbal cognitive load and hyperventilation would facilitate intrusion development immediately following exposure to the trauma film; however, this was not maintained at follow-up. Consistent with cognitive models of post-traumatic stress, thought suppression and the distress associated with intrusive experiences mediated the relationship between distress caused by the film and intrusions at 1-week follow-up. Objective memory testing indicated that the three experimental groups showed similar recall and recognition performance for the content of the film; however, relative to the control group, individuals in the cognitive load condition were significantly less able to place film scenes in the correct order.

Autobiographical memory for trauma: update on four controversies

Empirical research since the year 2000 on trauma and autobiographical memory in adults is reviewed and related to four enduring controversies in the field: Whether traumatic memories are inherently different from other types of autobiographical memory; whether memory for trauma is better or worse than memory for non-traumatic events; whether traumas can be forgotten and then recalled later in life; and whether special mechanisms such as repression or dissociation are required to account for any such forgetting. The review concludes that trauma and non-trauma memories differ substantially, but only in clinical and not in healthy populations. Whereas involuntary memory is enhanced in clinical populations, voluntary memory is likely to be fragmented, disorganised, and incomplete. Progress in experimental and neuroimaging research will depend on analysing how task performance is affected by the interaction of voluntary and involuntary memory and by individual tendencies to respond to trauma with increased arousal versus dissociation.

Dissociation and serenity induction

Dissociation is a common experience during or immediately after a traumatic event; yet, most of the current knowledge regarding dissociation is retrospective in nature. The aim of the present study investigated a non-pharmacological method of dissociative induction with a clinical sample. Participants with PTSD and non-trauma exposed participants were randomly assigned to receive either a dissociative induction, or a serenity induction, based on modified Velten mood induction procedures. Participants receiving the dissociative induction reported higher state-dissociation than those receiving the serenity induction. The PTSD group reported greater state dissociation than the non-trauma exposed group, regardless of induction. State dissociation was related to trait dissociation, PTSD severity, and depression. The present results provide an initial demonstration of the viability for inducing state dissociation in the laboratory with a PTSD sample.

Dissociation and pain perception: an experimental investigation

Dissociative symptoms and abnormalities in pain perception have been associated with a range of disorders. The authors tested whether experimentally induced increases in state dissociation would cause an analgesic response. Participants (N = 120) were randomized to a dissociation induction condition via audiophotic stimulation or a credible control condition and were compared on pre- and postchanges in subjective pain and immersion time in response to a standard cold pressor test. Unexpectedly, the dissociation induction led to small, but significant increases in subjective pain and did not lead to greater immersion time. An exploratory analysis revealed that increases in absorption and derealization significantly predicted increased subjective pain and increased immersion time, respectively.

Memory transfer for emotionally valenced words between identities in dissociative identity disorder

The present study aimed to determine interidentity retrieval of emotionally valenced words in dissociative identity disorder (DID). Twenty-two DID patients participated together with 25 normal controls and 25 controls instructed to simulate DID. Two wordlists A and B were constructed including neutral, positive and negative material. List A was shown to one identity, while list B was shown to another identity claiming total amnesia for the words learned by the first identity. The identity claiming amnesia was tested for intrusions from list A words into the recall of words from list B and recognition of the words learned by both identities. Test results indicated no evidence of total interidentity amnesia for emotionally valenced material in DID. It is argued that dissociative amnesia in DID may more adequately be described as a disturbance in meta-memory functioning instead of an actual retrieval inability.

An analogue study of intrusions

According to cognitive theorists, intrusive trauma memories have their origin in how information during the event is processed. Two studies investigated functional cognitive strategies during medical crises that might protect against intrusions. In Study 1, interviews with health-care professionals were used to identify cognitive strategies judged to be effective in controlling emotions and dealing with medical crises. Study 2 systematically manipulated the use of those strategies in a trauma analogue film paradigm. Experimental participants reported fewer intrusions, and less fear and avoidance of film-related stimuli during the subsequent week than controls. The manipulation did not affect anxiety during the film or memory disorganization. Implications for cognitive theories of intrusion development are discussed.

Trauma narratives in posttraumatic stress disorder: a review

Nineteen empirical studies providing evidence about the nature of trauma narratives in posttraumatic stress disorder (PTSD) were reviewed. Selected studies had participants with a diagnosis of PTSD or with PTSD symptoms. The studies used either linguistic indices or participants' rating of narrative quality. There was evidence of a relationship between PTSD specific pathology and the occurrence of sensory/perceptual references and disturbed temporal aspects. Evidence for PTSD-related narrative fragmentation was inconclusive, and there were little data about specific self-referential content. Poor validity and confusion of content and syntactic aspects of narrative organization limited the data on the organization of PTSD narratives. Approaches that address some of these limitations and allow narrative-based evaluation of memory for trauma in PTSD are outlined.

Dissociation related to subjective memory fragmentation and intrusions but not to objective memory disturbances

The present study was a replication of Kindt and Van den Hout (Behaviour Research and Therapy 41 (2003) 167) with several methodological adaptations. Two experiments were designed to test whether state dissociation is related to objective memory disturbances, or whether dissociation is confined to the realm of subjective experience. High trait dissociative participants (N(exp.1)=25; N(exp.2)=25) and low trait dissociative participants (N(exp.1)=25; N(exp.2)=25) were selected from normal samples (N(exp.1)=372; N(exp.2)=341) on basis of scores on the Dissociative Experience Scale (DES). Participants watched an extremely aversive film, after which state dissociation was measured by the Peri-traumatic Dissociative Experience Questionnaire (PDEQ). Memory disturbances were assessed 4h later (Exp. 1) or 1 week later (Exp. 2). Objective memory disturbances were assessed by a sequential memory task, items tapping perceptual representations (Exp. 1), or an open question with respect to the remembrance of the film (Exp. 2). Subjective memory disturbances were measured by means of visual analogue scales assessing fragmentation and intrusions. The two experiments provided a fairly exact replication of an earlier experiment (Behaviour Research and Therapy 41 (2003) 167-178), indicating a relation between dissociation and memory disturbances that appeared to be confined to the subjective experience of memory.

Dissociative experiences are related to commissions in emotional memory

Two rival hypotheses of the link between dissociative experiences and emotional memory were tested: 1) the defence mechanism hypothesis that assumes that dissociation promotes fragmentation of emotional memory; and 2) the fantasy proneness hypothesis that claims that because of its overlap with fantasy proneness, dissociation is related to commissions in emotional memory. Undergraduates scoring high (n = 19) or low (n = 19) on the Dissociative Experiences Scale (DES) listened to an aversive story. Next, a free recall task was administered. While high dissociators made more commission errors in their free recall than did low dissociators, fantasy proneness did not account for this difference.

Suppressing unwanted memories: where there is a will, there is a way?

Research suggests that suppressing unwanted thoughts, generally, is an ineffective thought control strategy, because suppression attempts oftentimes fail, and, furthermore, result in a paradoxical increase of unwanted thoughts, later on. The present study sought to investigate whether manipulated expectations about suppression efficacy determine actual effects of suppression attempts. To test this hypothesis, participants listened to an audiotaped story, and were subsequently appointed to one of four conditions: a no-instruction-control (n = 20), suppression (n = 20), suppression-works (n = 20; participants were told that suppression generally is a fruitful strategy), or suppression-does-not-work (n = 25; participants were told that suppression primarily has paradoxical effects) condition. Two hours later, participants' memories of the story were tested, and several metamemory questions were answered. Induced expectations actually determined the perceived efficacy of suppression attempts, as well as thought frequency, although perceived or actual accuracy of recollections was not affected by the instructions.