Stewart, L.H.; (2012) Capturing hypervigilance: attention biases in elevated trait anxiety and posttraumatic stress disorder. Doctoral thesis , UCL (University College London).

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Abstract

The work presented in this thesis aimed to investigate attentional processing of threat in anxious individuals and its relationship to the clinical anxiety symptom of hypervigilance. Four experimental chapters report a total of nine experiments. The first three experiments (chapters 2 and 3) describe a novel paradigm designed to measure attention bias to threat in a way which overcomes limitations of previous paradigms and which differentially measures engagement and disengagement stages of attention bias. No differences in performance were seen between high and low traitanxious individuals. Instead a general behaviour pattern was seen in which shifting location of attention aids disengagement from negative content. Additionally, adapting the task to a training paradigm demonstrated that both engagement and disengagement processes play causative roles in emotional reactivity. The series of experiments reported in chapter 4 investigated pre-conscious processing of (threat-related) traits in non-emotional faces. Highly trustworthy, untrustworthy and dominant faces (relative to neutral) took longer to reach awareness. Furthermore, the size of this effect was related to observers’ personality traits showing that preconscious evaluation of social dimensions arises from interactions between stimulus features and observer-specific traits. British war veterans showed the same effect for trustworthy faces but altered effects for faces varying in dominance traits. Finally, two eye-tracking experiments reported in chapter 5 captured hypervigilance in war veterans with and without PTSD. Veterans freely viewed photographs of neutral street scenes and a correlation was found between reported severity of hypervigilance and both number of saccades and duration of fixations. In a second experiment PTSD symptom related differences were seen in eye movements recorded whilst veterans walked London streets, although these did not match those see in the laboratory task. Overall, this thesis shows that multiple stages of processing are implicated in threat biases and that such biases in attention extend to traits other than anxiety. Additionally, anxiety-related alterations in behaviour are seen even in the absence of objective threat suggesting that preferential threat processing is only part of the picture.

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