Participants completed two measures of social anxiety: the Social Interaction Anxiety Scale (SIAS), which corresponds to Generalised Social Phobia in DSM-III-R (Mattick & Clarke, 1998), and the Social Phobia Scale (SPS), which corresponds to the criteria for Circumscribed Social Phobia in DSM-III-R (Mattick & Clarke, 1998). The SIAS measures fear of social interaction. The SPS assesses fear of being scrutinized during routine activities such as eating, drinking, and writing. The Barratt Impulsivity Scale version 11 (BIS-11), a paper based 30-item self-report scale, was administered to all participants. Participants rate their frequency on impulsive behaviours and traits or non impulsive behaviours and traits (Patton, Stanford, & Barratt, 1995). The BIS is the most frequently used self report measure of impulsivity (Dougherty, Mathias, Marsh, Moeller, & Swann, 2004), and has good validity and reliability (Moeller, et al., 2002; Patton, et al., 1995).
