Factor structure of the Social Interaction Anxiety Scale and the Social Phobia Scale

In the study of social anxiety, it is common to differentiate between social interaction versus performance anxiety. The Social Interaction Anxiety Scale was designed to assess social interaction anxiety, and the Social Phobia Scale to assess fear of scrutiny by others (Mattick and Clarke, 1989). In common use, these scales are typically administered together and treated as subscales of a larger measure. However, the joint factor structure of these instruments has never been examined; therefore, it is unclear whether or not the items on these scales actually represent distinct aspects of social anxiety. In the present study, a confirmatory factor analysis of the pooled items from the SIAS and SPS failed to adequately fit the data. An exploratory factor analysis yielded three factors: (1) interaction anxiety, (2) anxiety about being observed by others, and (3) fear that others will notice anxiety symptoms. However, hierarchical factor analysis suggested that these factors all load on a single higher-order factor, social anxiety. Relationships of the first-order factors to other measures of social and performance fear and avoidance are examined, and implications of our findings for the assessment of social phobia are discussed.