Presentation Title: Effects of Dissociation on Inhibitory Control in Posttraumatic Stress Disorder

Abstract: To explore differential cognitive processing to threat-related stimuli in PTSD, we administered a modified version of the Eriksen Flanker Task to individuals who met diagnostic criteria for PTSD, individuals who were exposed to a traumatic event (without PTSD), and healthy controls. Participants were shown a sequence of three lines, and asked to respond to the orientation of the second (target) line, superimposed on either a neutral or fearful image (faces or scenes). The presentation of stimuli in time (rather than spatially as in the traditional Eriksen Task), allowed us to collect electrophysiological data separately for flankers (first and last lines in the sequence) and targets. Both behavioral data and analyses of event-related potentials revealed that individuals with PTSD suffer general deficits in inhibitory control to distractors compared to healthy and trauma-exposed (non-PTSD) controls. Moreover, attentional interference was greatest in PTSD participants who scored high on the Multiscale Dissociation Inventory (MDI), a measure of dissociative symptomatology. Conversely, trauma-exposed participants (without PTSD) who scored high on the MDI evidenced better inhibitory control in our task. Theoretical perspectives on dissociation as a protective, adaptive mechanism will be explored. Findings will be related to existing research on the role of dissociation in the cognitive processing of trauma, including relevant treatment implications.

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