Perceptual processing during trauma, priming and the development of intrusive memories

Abstract

BackgroundIntrusive reexperiencing in posttraumatic stress disorder (PTSD) is commonly triggered by stimuli with perceptual similarity to those present during the trauma. Information processing theories suggest that perceptual processing during the trauma and enhanced perceptual priming contribute to the easy triggering of intrusive memories by these cues.MethodsHealthy volunteers (N = 51) watched neutral and trauma picture stories on a computer screen. Neutral objects that were unrelated to the content of the stories briefly appeared in the interval between the pictures. Dissociation and data-driven processing (as indicators of perceptual processing) and state anxiety during the stories were assessed with self-report questionnaires. After filler tasks, participants completed a blurred object identification task to assess priming and a recognition memory task. Intrusive memories were assessed with telephone interviews 2 weeks and 3 months later.ResultsNeutral objects were more strongly primed if they occurred in the context of trauma stories than if they occurred during neutral stories, although the effect size was only moderate (ηp2=.08) and only significant when trauma stories were presented first. Regardless of story order, enhanced perceptual priming predicted intrusive memories at 2-week follow-up (N = 51), but not at 3 months (n = 40). Data-driven processing, dissociation and anxiety increases during the trauma stories also predicted intrusive memories. Enhanced perceptual priming and data-driven processing were associated with lower verbal intelligence.LimitationsIt is unclear to what extent these findings generalize to real-life traumatic events and whether they are specific to negative emotional events.ConclusionsThe results provide some support for the role of perceptual processing and perceptual priming in reexperiencing symptoms.

Differential effects of sleep on explicit and implicit memory for potential trauma reminders: findings from an analogue study

“…Despite the lack of group differences in priming, sleep deprivation could affect other types of implicit memory (Lissek & van Meurs, 2015). The current study investigated effects of partial sleep deprivation on priming, as this aspect of implicit memory is strongly linked to intrusion development in healthy participants and PTSD patients (Ehlers et al, 2006;Michael & Ehlers, 2007;Sündermann et al, 2013). Critically, longitudinal studies indicate that priming predicts the course of symptom development in PTSD Kleim et al, 2012;Michael et al, 2005b).…”

“…Although we did not find correlations between explicit memory and intrusions, the direction of group differences aligns with this assumption. Moreover, it is important to consider our sample size in light of the strength of correlations found using the current paradigm (e.g., r = −.28, Sündermann et al, 2013). Our study was thus not sufficiently powered to examine correlations between explicit/implicit memory performance and intrusions.…”

“…Picture stories 'Traumatic' picture stories were taken from Holz et al (2014). Using a between-subjects design, the authors examined priming for 'traumatic' and neutral stories and found that priming was significantly enhanced for 'traumatic' stories as compared to neutral stories (see also Sündermann et al, 2013). Hence, the validity of the paradigm has been established, allowing us to include only 'traumatic' stories in the current study.…”

“…This assumption is based on clinical observations suggesting that intrusions are often triggered by environmental stimuli that are perceptually similar to those related to the trauma (Ehlers et al, 2004). To account for this observation, theories posit that strong implicit encoding of trauma-associated stimuli subsequently reduces the perceptual threshold of similar, but unrelated environmental stimuli (Ehlers, Michael, Chen, Payne, & Shan, 2006;Michael & Ehlers, 2007;Sündermann, Hauschildt, & Ehlers, 2013). Thereby, implicit learning may conceivably yield a broad range of potential triggers for intrusive memories.…”

Interindividual Variability in Stress Susceptibility: A Role for Epigenetic Mechanisms in PTSD

“…Although genes and environment can produce shifts in risk and resilience on their own, the strongest phenotypic effects are associated with gene-environment interactions that are mediated by epigenetic modifications (Caspi and Moffitt, 2006; Chertkow-Deutsher et al, 2010; Dudley et al, 2011; Russo et al, 2012; Klengel et al, 2013; Zovkic and Sweatt, 2013). Environmental factors are particularly influential during early life, when they interact with epigenetic mechanisms to lastingly alter the expression of a broad range of genes (Sundermann et al, 2012, 2013). …”