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.     

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.     

Trauma‐related rumination mediates the effect of naturally occurring depressive symptoms but not momentary low mood on trauma intrusions

Comorbid depression is known to contribute to the maintenance of posttraumatic stress disorder (PTSD) including distressing intrusive trauma memories. It is theorised that depression is a risk factor for persistent PTSD through preventing optimal habituation of distress provoked by trauma memories and reminders, but the underlying cognitive mechanisms responsible are uncertain. The present study investigated trauma‐related rumination as a possible mediator for the effect of depression on trauma intrusions. Participants received a low mood induction or control procedure. Following viewing an analogue trauma film, frequency of film‐related intrusions and associated distress levels were measured and at 1‐week follow‐up. Between the two occasions, participants rated their levels of rumination about the film. Existing depression symptoms but not induced momentary sad mood predicted frequency of film intrusions and associated distress at 1‐week follow‐up. Some evidence was found that ruminative trauma processing mediated the relationship between baseline depressive symptoms and later intrusion frequency and associated distress. Future research is warranted to better understand the role of rumination in the depression–intrusion relationship, which may shed light on the clinical applicability of rumination‐targeted intervention for PTSD and comorbid depression.     

Count out your intrusions: Effects of verbal encoding on intrusive memories

Peri-traumatic information processing is thought to affect the development of intrusive trauma memories. This study aimed to replicate and improve the study by Holmes, Brewin, and Hennessy (2004, Exp. 3) on the role of peri-traumatic verbal processing in analogue traumatic intrusion development. Participants viewed an aversive film under one of three conditions: counting backwards in 3s (“verbal interference”), verbalising emotions and thoughts (“verbal enhancement”), or without an extra task. A dual-process account of PTSD would predict that verbal interference would increase intrusion frequency compared to no task, whereas verbal enhancement would lead to a decrease. In contrast, mainstream memory theory predicts a decrease in intrusion frequency from any concurrent task that diverts attention away from the trauma film. The main finding was that the verbal interference task led to a decrease in intrusive memories of the film compared to the other two conditions. This finding does not support a dual-process account of PTSD, but is in line with general theories of memory and attention.     

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.     

“Why” or “How”: The Effect of Concrete Versus Abstract Processing on Intrusive Memories Following Analogue Trauma

Emergency service workers, military personnel, and journalists working in conflict zones are regularly exposed to trauma as part of their jobs and suffer higher rates of posttraumatic stress compared with the general population. These individuals often know that they will be exposed to trauma and therefore have the opportunity to adopt potentially protective cognitive strategies. One cognitive strategy linked to better mood and recovery from upsetting events is concrete information processing. Conversely, abstract information processing is linked to the development of anxiety and depression. We trained 50 healthy participants to apply an abstract or concrete mode of processing to six traumatic film clips and to apply this mode of processing to a posttraining traumatic film. Intrusive memories of the films were recorded for 1 week and the Impact of Events Scale–Revised (IES-R; Weiss & Marmar, 1997) was completed at 1-week follow-up. As predicted, participants in the concrete condition reported significantly fewer intrusive memories in response to the films and had lower IES-R scores compared with those in the abstract condition. They also showed reduced emotional reactivity to the posttraining film. Self-reported proneness to intrusive memories in everyday life was significantly correlated with intrusive memories of the films, whereas trait rumination, trait dissociation, and sleep difficulties were not. Findings suggest that training individuals to adopt a concrete mode of information processing during analogue trauma may protect against the development of intrusive memories.     

Intrusive images and intrusive thoughts as different phenomena: Two experimental studies

According to the dual representation theory of PTSD, intrusive trauma images and intrusive verbal thoughts are produced by separate memory systems. In a previous article it was shown that after watching an aversive film, participants in non-movement conditions reported more intrusive images than participants in a free-to-move control condition (Hagenaars, Van Minnen, Holmes, Brewin, & Hoogduin, 2008). The present study investigates whether the experimental conditions of the Hagenaars et al. study had a different effect on intrusive thoughts than on intrusive images. Experiment 2 further investigated the image–thoughts distinction by manipulating stimulus valence (trauma film versus neutral film) and assessing the subsequent development of intrusive images and thoughts. In addition, both experiments studied the impact of peri-traumatic emotions on subsequent intrusive images and thoughts frequency across conditions. Results showed that experimental manipulations (non-movement and trauma film) caused higher levels of intrusive images relative to control conditions (free movement and neutral film) but they did not affect intrusive thoughts. Peri-traumatic anxiety and horror were associated with subsequent higher levels of intrusive images, but not intrusive thoughts. Correlations were inconclusive for anger and sadness. The results suggest intrusive images and thoughts can be manipulated independently and as such can be considered different phenomena.     

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.     

The role of tonic immobility and control in the development of intrusive memories after experimental trauma

ABSTRACT

Tonic immobility (TI; state of motor inhibition during threat) has been implicated in the onset of intrusive trauma memories, while controllability was associated with reduced anxiety. The present study investigated the interaction between TI and control in the development of intrusive memories of an analogue trauma. Sixty-four participants watched negative pictures while being allowed to close their eyes (InControl) or not (NoControl). They completed measures for spontaneous TI afterwards and recorded intrusive memories of the pictures in a diary in the subsequent week. Bayesian analyses were used to test informative hypotheses. Spontaneous TI during picture viewing was positively associated with increased intrusion frequency. Intrusion frequency did not differ for InControl versus NoControl. Moderation (control x TI) and non-moderation (main effect of TI only) were both adequate models, with no preference. Our results confirm the importance of TI in PTSD development. Implications of the findings regarding control merit more research.     

Characteristics of intrusive memories in a community sample of depressed, recovered depressed and never-depressed individuals

An accumulating body of evidence has revealed that intrusive autobiographical memories of negative events play a role in depression. Despite increasing understanding of the phenomenological experience of these memories, previous research in this area has been conducted in either nonclinical samples, or in clinical samples without an adequate control group. This study aimed to replicate and extend findings with dysphoric samples by comparing the content and characteristics of intrusive memories in clinically depressed (n = 25), recovered (n = 30) and never-depressed (n = 30) participants. Participants completed mood measures, and a battery of self-report questionnaires that indexed intrusive memory frequency, avoidance and characteristics. Intrusive memories were common and shared strikingly similar characteristics across the three groups. The key finding was that depressed participants reported higher levels of intrusion-related distress, associated emotions (especially sadness and helplessness), interference as a result of the memories and memory vividness compared to the never-depressed group. Despite similar levels of intrusion, there were group differences in avoidance such that depressed participants reported higher levels of avoidance than the never-depressed group. These results provide further support for the proposal that clinical interventions for depression could usefully incorporate components that aim to reduce intrusive autobiographical memories and target avoidance strategies.     

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.     

The effect of emotional stress on involuntary and voluntary conscious memories

Clinical theories of post-traumatic stress disorder often claim that intrusive (involuntary) memories favour emotionally stressful material and that these memories come with more sensory imagery and emotional reliving compared to voluntary memories. However, these assumptions have not been verified experimentally. Here we obtained recordings of emotional reactions to aversive pictures at the time of encoding, as well as records of involuntary and voluntary memories of these pictures in a subsequent diary study. A comparison of individual ratings, obtained during encoding, of pictures recalled involuntarily and voluntarily showed that emotional stress at encoding increased overall accessibility, independent of whether recall was voluntary or involuntary. However at the time of recall, voluntary memories scored higher on narrative content and on measures of imagery. The findings are compatible with research on emotion and memory in general, but challenge clinical claims of differential involuntary versus voluntary access to emotionally stressful events.     

Individual differences in the suppression of unwanted memories: the executive deficit hypothesis

When confronted with reminders to an unpleasant memory, people often try to prevent the unwanted memory from coming to mind. In this article, we review behavioral and neurocognitive evidence concerning the consequences of exerting such control over memory retrieval. This work indicates that suppressing retrieval is accomplished by control mechanisms that inhibit the unwanted memories, making them harder to recall later, even when desired. This process engages executive control mechanisms mediated by the lateral prefrontal cortex to terminate recollection-related activity in the hippocampus. Together, these findings specify a neurocognitive model of how memory control operates, suggesting that executive control may be an important means of down-regulating intrusive memories over time. We conclude by proposing that individual differences in the regulation of intrusive memories in the aftermath of trauma may be mediated by pre-existing differences in executive control ability. In support of this executive deficit hypothesis, we review the recent work indicating links between executive control ability and memory suppression.     

Using stressful films to analyze risk factors for PTSD in analogue experimental studies – which film works best?

Abstract

To understand mental disorders, analogue paradigms provide an indispensable contribution. In posttraumatic stress disorder (PTSD), the stressful film paradigm is a frequently used analogue approach: Films depicting traumatic events are shown to non-clinical participants in order to elicit stress responses analogue to responses to traumatic events in real life. Previous studies used a large variety of films, which is problematic with regard to the comparability of results. The main goal of this study was to identify a film clip that (a) consistently provokes stress reactions and (b) provokes reactions that are as similar as possible to traumatic stress.

We randomly exposed 105 male and female participants to one of four stressful films, differing, e.g., in content and origin. Intrusive memories of the film, reported immediately after the film and during a diary phase of three days, as well as distress, heart rate, and several mood states were measured. A film clip depicting rape elicited the most consistent reactions that were characterized by a higher heart rate, more distress and more intrusive memories, compared to the other three clips. Intrusive memories across all films were especially related to an increase in heart rate and disgust in response to the film.     

Previous attentional set can induce an attentional blink with task-irrelevant initial targets

Identification of a second target is often impaired by the requirement to process a prior target in a rapid serial visual presentation (RSVP). This is termed the attentional blink. Even when the first target is task irrelevant an attentional blink may occur providing this first target shares similar features with the second target (contingent capture). An RSVP experiment was undertaken to assess whether this first target can still cause an attentional blink when it did not require a response and did not share any features with the following target. The results revealed that such task-irrelevant targets can induce an attentional blink providing that they were task relevant on a previous block of trials. This suggests that irrelevant focal stimuli can distract attention on the basis of a previous attentional set.     

Intrusive re‐experiencing in post‐traumatic stress disorder: Phenomenology,theory, and therapy

The article describes features of trauma memories in post‐traumatic stress disorder (PTSD), including characteristics of unintentional re‐experiencing symptoms and intentional recall of trauma narratives. Re‐experiencing symptoms are usually sensory impressions and emotional responses from the trauma that appear to lack a time perspective and a context. The vast majority of intrusive memories can be interpreted as re‐experiencing of warning signals, i.e., stimuli that signalled the onset of the trauma or of moments when the meaning of the event changed for the worse. Triggers of re‐experiencing symptoms include stimuli that have perceptual similarity to cues accompanying the traumatic event. Intentional recall of the trauma in PTSD may be characterised by confusion about temporal order, and difficulty in accessing important details, both of which contribute to problematic appraisals. Recall tends to be disjointed. When patients with PTSD deliberately recall the worst moments of the trauma, they often do not access other relevant (usually subsequent) information that would correct impressions/predictions made at the time. A theoretical analysis of re‐experiencing symptoms and their triggers is offered, and implications for treatment are discussed. These include the need to actively incorporate updating information ( “I know now …”) into the worst moments of the trauma memory, and to train patients to discriminate between the stimuli that were present during the trauma ( “then”) and the innocuous triggers of re‐experiencing symptoms ( “now”).     

Blink and shrink: the effect of the attentional blink on spatial processing

The detection or discrimination of the second of 2 targets in a rapid serial visual presentation (RSVP) task is often temporarily impaired-a phenomenon termed the attentional blink. This study demonstrated that the attentional blink also affects localization performance. Spatial cues pointed out the possible target positions in a subsequent visual search display. When cues were presented inside an attentional blink (as induced by an RSVP task), the observers' capacity to use them was reduced. This effect was not due to attention being highly focused, to general task switching costs, or to complete unawareness of the cues. Instead, the blink induced a systematic localization bias toward the fovea, reflecting what appears to be spatial compression.     

The attentional blink reflects retrieval competition among multiple rapid serial visual presentation items: tests of an interference model

When people respond to a target (T1) in a rapid serial visual presentation stream, their perception of a subsequent target (T2) is impaired if the intertarget stimulus onset asynchrony is between about 100 and 500 ms. Three experiments supported the interference model's (K. L. Shapiro, J. E. Raymond, & K. M. Arnell, 1994) claim that this attentional blink reflects competition for retrieval among multiple items in visual short-term memory. Experiments 1 and 2 revealed that items appearing during the blink are named as T2 on an above-chance proportion of trials when T2 must be identified. Experiment 3 demonstrated that both the size of the blink and sensitivity to T2 reflected the number of items competing for retrieval as T2; such competition, moreover, occurred at a conceptual or categorical level rather than at a purely visual one. The relationship between the interference and alternative models of the attentional blink is discussed.