Johan Verwoerd

Individual differences in experiencing intrusive memories : The role of the ability to resist proactive interference

This study explored whether a relatively poor ability to resist or inhibit interference from irrelevant information in working memory is associated with experiencing undesirable intrusive memories. Non-selected participants (N=91) completed a self-report measure of intrusive memories, and carried out experimental tasks intended to measure two different types of inhibition: resistance to proactive interference and response inhibition (i.e., the ability to prevent automatically triggered responses). The results showed a significant relationship between inhibition at the cognitive level (i.e., resistance to proactive interference) and the frequency of intrusive memories (especially in the group of female participants) whereas no such relationship with measures of response inhibition emerged. These findings are consistent with the idea that deficient inhibitory control reflects a vulnerability factor for experiencing intrusive memories. Implications for research investigating risk factors for the development of posttraumatic stress disorder (PTSD) are discussed.

Pre-stressor cognitive control is related to intrusive cognition of a stressful film

It has been suggested that relatively weak cognitive control existing prior to a stressful event may be associated with intrusive memories of that stressor afterwards. We explored this in two analog studies employing unselected participants who saw an emotional film fragment and completed behavioral (i.e., color-naming interference [CNI]) and self-report indices of intrusions. Prior to film presentation, several cognitive control tests were administered. Study 1 showed that better updating/monitoring was linked to less CNI from negative film-related words. However, better updating/monitoring was associated with more diary reports of intrusive memories. Study 2 showed that a better resistance to pro-active interference (PI) predicted less self-reported film-related intrusive cognition after 24h. However, after this delay, both self-reported intrusions and CNI were not related to updating/monitoring. Taken together, the results suggest that a specific pre-existing cognitive control function (i.e., resistance to PI) may be involved in the regulation of post-stressor intrusive memory phenomena.

Preferential processing of visual trauma-film reminders predicts subsequent intrusive memories

This study used an analogue design to test the hypothesis that preferential processing of visual trauma reminders in the aftermath of a stressful or traumatic event gives rise to subsequent intrusive memories. Shortly after the presentation of a stressful film fragment, participants (n=36) were asked to detect neutral targets (rotated buildings or nature scenes) in a single target rapid serial visual presentation (RSVP) paradigm. During half of the streams, the target was preceded by a distracter. The distracters consisted of visual images extracted from an earlier presented stressful film (e.g., persons and objects that figured in the film). The degree of interference by these film reminders predicted subsequent intrusions recorded in a one-week diary. The results provide evidence that a deficient ability to obtain attentional control over perceptual “trauma” reminders during goal-directed behaviour may set people at risk for persistent intrusive memories. Implications for research investigating attentional bias and intrusive memories in context of posttraumatic stress disorder (PTSD) are discussed.

Fewer intrusions after an attentional bias modification training for perceptual reminders of analogue trauma

The present experimental analogue study used computerised attention training to investigate the role of attention bias in the prediction of intrusive memories. After exposure to a trauma film, participants in a training group (n=22) were presented with a variant of the exogenic cueing task (ECT) in which visual film reminders (i.e., stills from the trauma film) were always presented during invalid and neutral control stimuli always during valid trials. The purpose of this cue–location contingency was reinforcing the direction of attention away from film reminders. Control participants (n=23) performed a similar training without such a contingency. Post-training processing bias was assessed with a single target Rapid Serial Visual Presentation (RSVP) task, in which trauma-film reminders served as task-irrelevant distracters appearing shortly before a neutral target. The frequency of film-related intrusions was recorded in a take-home diary and at a follow-up session three days after film viewing. Participants who underwent attention training reported fewer film-related intrusions and showed less interference by visual film distracters than controls. Implications for research on attention bias after real-life trauma are discussed.

Cognitive control and suppression of memories of an emotional film.

Relatively weak cognitive control existing prior to a stressful event may be associated with intrusive memories of that stressor afterwards. To test this possibility, we tested participants under circumstances that putatively decrease cognitive control and explored how this affected the relation between indices of cognitive control and intrusive memories. Evening type participants (N = 80) were tested at either an optimal or a non-optimal time of day. Tests of working memory capacity and inhibitory control were administered. Subsequently, participants saw an emotional film fragment and engaged in thought suppression afterwards. Results show different correlational patterns in time-of-testing groups. At non-optimal times there were negative, but relatively weak correlations between working memory capacity and intrusions. Better inhibitory control was associated with fewer intrusions during the initial minute of the thought suppression period and with fewer self-reported intrusions. At optimal times however, these correlations were absent. Working memory capacity even showed robust correlations in the opposite direction. These findings cast doubts on the suitability of indices of working memory capacity for testing the idea that relatively weak cognitive control is linked to intrusive memory phenomena. Specific measures of inhibitory control may prove to be more appropriate for testing this idea.

Modification of cognitive biases related to posttraumatic stress: A systematic review and research agenda

Cognitive models of Posttraumatic Stress Disorder (PTSD) postulate that cognitive biases in attention, interpretation, and memory represent key factors involved in the onset and maintenance of PTSD. Developments in experimental research demonstrate that it may be possible to manipulate such biases by means of Cognitive Bias Modification (CBM). In the present paper, we summarize studies assessing cognitive biases in posttraumatic stress to serve as a theoretical and methodological background. However, our main aim was to provide an overview of the scientific literature on CBM in (analogue) posttraumatic stress. Results of our systematic literature review showed that most CBM studies targeted attentional and interpretation biases (attention: five studies; interpretation: three studies), and one study modified memory biases. Overall, results showed that CBM can indeed modify cognitive biases and affect (analog) trauma symptoms in a training congruent manner. Interpretation bias procedures seemed effective in analog samples, and memory bias training proved preliminary success in a clinical PTSD sample. Studies of attention bias modification provided more mixed results. This heterogeneous picture may be explained by differences in the type of population or variations in the CBM procedure. Therefore, we sketched a detailed research agenda targeting the challenges for CBM in posttraumatic stress.

Collaboration enhances later individual memory for emotional material

ABSTRACT Research on collaborative remembering suggests that collaboration hampers group memory (i.e., collaborative inhibition), yet enhances later individual memory. Studies examining collaborative effects on memory for emotional stimuli are scarce, especially concerning later individual memory. In the present study, female undergraduates watched an emotional movie and recalled it either collaboratively (n = 60) or individually (n = 60), followed by an individual free recall test and a recognition test. We replicated the standard collaborative inhibition effect. Further, in line with the literature, the collaborative condition displayed better post-collaborative individual memory. More importantly, in post-collaborative free recall, the centrality of the information to the movie plot did not play an important role. Recognition rendered slightly different results. Although collaboration rendered more correct recognition for more central details, it did not enhance recognition of background details. Secondly, the collaborative and individual conditions did not differ with respect to overlap of unique correct items in free recall. Yet, during recognition former collaborators more unanimously endorsed correct answers, as well as errors. Finally, extraversion, neuroticism, social anxiety, and depressive symptoms did not moderate the influence of collaboration on memory. Implications for the fields of forensic and clinical psychology are discussed.

Influence of sad mood induction on implicit self-esteem and its relationship with symptoms of depression and anxiety

BACKGROUND AND OBJECTIVES Implicit self-esteem (ISE) refers to the valence of triggered associations when the self is activated. Despite theories, previous studies often fail to observe low ISE in depression and anxiety. It is feasible that sad mood is required to activate dysfunctional self-associations. The present study tested the following hypotheses: i) ISE is lower following a sad mood induction (SMI); ii) the relationship between ISE and level of depression/anxiety symptoms is relatively strong when ISE is measured during sad mood; iii) individuals with higher levels of depression/anxiety symptoms will show a relatively large decrease in ISE following a SMI. METHODS In this mixed-designed study, university students completed the self-esteem implicit association test (IAT) either at baseline (control condition; n = 46) or following a SMI (experimental condition; n = 49). To test the third hypothesis, a SMI and IAT were also given in the control condition. Both conditions completed self-report measures of explicit self-esteem (ESE), and symptoms of depression and anxiety. RESULTS There was no support for the first two hypotheses, but some support that symptoms of anxiety correlated with larger decreases in ISE following a SMI which partly supported the third hypothesis. This disappeared when controlling for multiple testing. LIMITATIONS Results are limited to non-clinical participants. CONCLUSIONS While ISE was robust against increases in sad mood, there was some tentative support that symptoms of anxiety were related to larger decreases in ISE following a SMI.