Individual differences in emotionality and peri-traumatic processing

Abstract

Background and objectives

Recent cognitive models propose that intrusive trauma memories arise and persist because high levels of emotional arousal triggered by the trauma disrupt conceptual processing of elements of the event, while enhancing sensory/perceptual processing. A trauma film analogue design was used to investigate if the predicted facilitating effects on intrusions from inhibiting conceptual processing and predicted attenuating effects on intrusions from inhibiting sensory processing are moderated by individual differences in emotionality.

Methods

One hundred and five non-clinical participants viewed a traumatic film while undertaking a conceptual interference task, a sensory interference task, or no interference task. Participants recorded the frequency and intensity of intrusions over the following week.

Results

There was no facilitating effect for the conceptual interference task compared to no interference task. A significant attenuation of the frequency of intrusions was evident for those undertaking sensory interference (ŋ² = .04). This effect, however, was only present for those with high trait anxiety (d = .82) and not for those with low trait anxiety (d = .08). Relative to high trait anxious controls, high anxious participants who undertook sensory interference also reported lower intensity of intrusions (d = .66).

Conclusions

This is the first trauma film analogue study to show that the attenuating effect of concurrent sensory/perceptual processing on the frequency and intensity of subsequent intrusions is evident only for people with high trait anxiety. The results have implications for conceptual models of intrusion development and for their application to the prevention of post traumatic distress.

Introduction

Intrusive, distressing and highly vivid memories of the traumatic event are the most commonly reported post trauma re-experiencing sensation (Kuyken and Brewin, 1994, Regambal and Alden, 2009). When they persist in their intensity and are associated with high levels of distress, impairment and attempts to avoid, they are a hallmark symptom for a diagnosis of post traumatic stress disorder (PTSD). Consequently, understanding how intrusive memories of trauma arise and how they are maintained over time has become a central focus of many psychological models of PTSD.

Many of these models conceptualise intrusive memories as an outcome of how the trauma event information is processed during the experience of the trauma (Brewin et al., 1996, Ehlers and Clark, 2000). While they differ in details, these models propose that multiple pathways underlie memory formation and that, for some people, high levels of emotional arousal during a trauma can significantly disrupt cognitive processing of the most distressing parts of the event. In particular, the models propose that this disruption inhibits usual conceptual or verbal processing towards stronger sensory and perceptual processing. This focus results in the event being encoded predominantly as sensory or perceptual information with less encoding of the trauma as explicit, narrative and verbal memories (Brewin and Holmes, 2003, Buckley et al., 2000, Ehlers and Clark, 2000, Halligan et al., 2002). Intrusive memories are thought to arise because this sensory dominated representation of the trauma can be easily triggered by similar sensory or perceptual cues (Brewin, Gregory, Lipton, & Burgess, 2010). In addition, because there is a deficit in associations to a corresponding conceptual, verbal representation, certain traumatic moments or parts of the event lack contextual information. As a result trauma memories are experienced as intrusive with a sensory immediacy and as a current threat rather than as a memory of a contextualized past event.

Several studies have examined the peri-traumatic cognitive processes outlined in these models through an analogue film paradigm (see Holmes & Bourne, 2008 for a review). In this paradigm a film depicting traumatic material is shown to participants to elicit a short-term trauma response and intrusive memories of the film are recorded in self-monitoring over the following days. While it has external validity limitations, the trauma film paradigm allows the experimental manipulation of trauma information processing factors and reduces reliance on retrospective reports. Taken together, trauma film analogue studies have been shown to induce negative mood, distress, dissociation and intrusive memories for the film content (Holmes & Bourne, 2008).

Some studies have used the film paradigm to directly investigate whether inhibiting sensory/perceptual processing of the film by asking participants to perform a concurrent visuospatial task, such as key tapping or clay modelling, interferes with sensory/perceptual processing and decreases the frequency of intrusive memories (Bourne et al., 2010, Holmes et al., 2004, Krans et al., 2010, Stuart et al., 2006). These studies have consistently found a significant reduction in the frequency of intrusive memories when participants perform a concurrent visuospatial task in comparison to a control condition with no assigned task. However, findings from studies investigating the impact of performing a concurrent verbal/conceptual task (e.g., counting backwards by threes) whilst watching an aversive film have been less consistent. Some studies have found an increase in intrusions consistent with the cognitive model (Holmes et al., 2004), while others have found fewer intrusions using the same conceptual interference task (Krans, Näring, & Becker, 2009). Bourne et al. (2010) reported that while there was a non-significant increase in intrusions for the counting backwards by threes task, a more cognitively demanding verbal interference task (counting backwards by sevens) led to significantly more post film intrusions compared to a non interference group. The competing roles of task modality and the cognitive load imposed by the interference task were demonstrated in a recent study using affective pictures to elicit intrusions (Pearson & Sawyer, 2011). The result of that study confirmed a relative reduction in the frequency of intrusive memories when participants perform a concurrent visuospatial task but also showed a reduction in intrusions for a nonspatial interference task. In addition, that study found that a verbal interference task produced a reduction in intrusion frequency with reductions in intrusion frequency for both visuospatial and verbal task associated with the degree of complexity of the interference tasks. Overall, these data suggest that the attentional demands of the interference task need to be considered as a possible moderator of the impact of interference tasks on intrusions. Taken together, previous studies indicate not only that the analogue film paradigm is useful for exploring the development of intrusive memories, but also that instructing participants to use specific types of peri-traumatic cognitive strategies results in significant differences in the subsequent experience of intrusive memories.

There is also some evidence consistent with the link between levels of emotional arousal triggered during a trauma and the development of intrusive memories proposed by the multiple pathways models. A number of studies have demonstrated that a disposition to negative emotionality is linked with intrusive memory development (Borja, Callahan, & Rambo, 2009), prolongs the persistence of intrusive memories following trauma (Bryant et al., 2000, Holmes et al., 2005) and predicts the likelihood of an individual experiencing distressing and intrusive recollections of a trauma stimulus (Regambal & Alden, 2009). Other studies looking at individual differences in vulnerability to express negative emotional symptoms during stress have found that emotional reactivity is a strong predictor of the intensity of PTSD symptoms (Strelau & Zawadzki, 2005) and duration of distress (Marshall, Miles, & Stewart, 2010). None of this evidence bears directly on the proposal that intrusive memories arise because the emotional impact of the trauma disrupts conceptual processing of event. One way to directly test this proposal would be to examine whether individual differences in disposition to emotionality influences the impact of modality specific cognitive interference tasks on intrusion development. Higher emotionality should enhance both the intrusion facilitating effect of verbal/conceptual interference and intrusion attenuating effect of visuospatial interference. As far as we are aware no studies have linked individual differences in emotionality to the development of intrusions within the trauma film paradigm.

The main aim of the current study is to examine the influences of individual differences in emotionality on the frequency and persistent of intrusions after viewing a traumatic film under differing cognitive interference conditions. We also include measures of the subjective intensity of the intrusive memory because of the importance of the emotional strength of the intrusion in motivating avoidance. Emotionality will be determined through the measurement of trait anxiety and sensitivity to physiological reactivity to stress. Trait anxiety reflects an enduring disposition to respond with high level of emotionality to threat while sensitivity to physiological reactivity represents individual differences in the degree to which emotional reactivity is experienced as adverse. Consistent with previous research using analogue films we predict that participants’ anxiety level and negative emotion will significantly increase after watching the aversive film stimulus. Secondly, we hypothesize that in line with the multiple pathways model (Holmes et al., 2004) participants who are assigned to a verbal/conceptual interference task will report more intrusions and distress compared to a control group. Similarly, participants assigned to a sensory/perceptual interference task will report fewer intrusions and distress compared to a control group. The study considers the role of attention as a moderating factor to the development of intrusions. In addition, we expect that emotionality will moderate the effects of the two types of cognitive interference on the frequency and intensity of subsequent intrusive memories of the film content. The relative enhancement of intrusions for participants performing a concurrent verbal/conceptual task will be strongest for those with high levels of emotionality. The relative inhibition of intrusions for participants performing a concurrent sensory/perceptual interference task will be most pronounced for those with high levels of emotionality.