Masters Thesis

Posttraumatic stress disorder: desensitization to non-trauma related negative stimuli

Negative expectations of one's self, others, or the world and emotional numbing are debated symptoms of posttraumatic stress disorder (APA, 2013). To provide electrophysiological evidence for these symptoms, and show that negative expectations and numbing are an automatic process rather than a product of rational thought, participants were given an adapted visual oddball paradigm with stimuli from the Reflexive Imagery Task. In order to measure an expectation violation, the stimuli were set up in valence-congruent and valence-incongruent trials, in which target images were preceded by three context images. We found that individuals with subclinical PTSD have smaller P300 amplitudes to negative images followed by a negative context due to desensitization or numbing to negative stimuli. Keywords: PTSD, ERP, P300, negative expectations, emotional numbing

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