The Effects of Brief Visual Stimuli on the Anxious Arousal Associated with Public Speaking

Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. Richard Spates

Second Advisor

Dr. Scott Gaynor

Third Advisor

Dr. Lisa Baker

Fourth Advisor

Dr. Ellen Koch


Public speaking anxiety as a form of social phobia has been the topic of numerous research investigations (Anderson, Rothbaum, & Hodges, 2003; Anderson, Zimand, Hodges, & Rothbaurn, 2005; Foley & Spates, 1996; Harris, Kemmerling, & North, 2002; Klinger et al., 2005; Waller, 2004). Exposure based treatments are the standard form of therapy for public speaking anxiety and have been implemented in massed form and in repeated intervals of relatively shorter duration. This study manipulated the duration of exposure to visual images of the feared situation by subjecting the stimuli to the technique of backward masking. This study examined whether a period of exposure so short as to be unreportable, could bring about a reduction in anxious arousal and self reported levels of anxiety in the course of a single exposure session, minus the training in anxiety management. Forty nine participants were randomly assigned to five conditions consisting of (a) the backwardly masked images condition-1, (b) the backwardly masked images condition-2 (c) the easily reportable images condition, (d) the target images only condition, and (e) the mask images only (control) condition to examine this proposition. Pre and post-exposure anxiety were assessed via facial electromyogram (fEMG) at the corrugator supercilii muscle and self report measures. Self-report measures consisted of the Profile of Mood States questionnaire and ratings of subjective units of distress. Within session continuous changes in anxiety were also assessed via fEMG. Contrary to expectation, it was found that individuals in the backwardly masked images condition did not display a greater reduction in anxiety as compared to individuals in the other three conditions. When images were displayed for a slightly longer duration, which allowed individuals to see both the target and the mask, a greater reduction in anxiety was observed.

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