Cost and Probability Biases in Social Phobia: Evaluating Their Relation to Attention Bias and Treatment Outcome

Social phobia is maintained in part by judgmental biases concerning the probability and cost of negative social events. One hypothesized mechanism of action of cognitive behavioral therapy (CBT) for anxiety disorders is its reduction in the exaggerated probabilities and costs associated with feared out‐ comes, termed the " cognitive mediation hypothesis " (Foa & Kozak, 1986). A number of studies have ex‐ amined the cognitive mediation hypothesis; some investigations find cost bias to be more important to treatment outcome, whereas others find probability bias to be more important. However, methodologi‐ cal limitations of several of these studies leave open the possibility that changes in judgmental biases are simply correlates or consequences of social anxiety reduction. Attentional processes, which mark the first discrimination of incoming information, may serve as precursors to cognitive processes like proba‐ bility and cost estimates. Though intuitively linked, whether social phobics' pattern of attending to ex‐ ternal threat cues is correlated with their appraisals of the cost and probability of negative events has yet to be examined empirically. The current project examines cost and probability biases and their rela‐ tion to attention bias and treatment outcome in a randomized controlled trial of CBT for social phobia. It was found that, contrary to hypotheses, greater attentional bias for threat in either direction (vigilance or avoidance) did not predict higher cost and probability estimates. However, a significant relation was observed between attentional vigilance and outcome probability estimates, such that greater vigilance for threat predicted greater estimates of the likelihood that negative social events will occur. As hypoth‐ esized, early changes in cost and probability biases predicted later changes in social anxiety symptoms (and not vice versa). Changes in probability estimates were a stronger predictor of treatment outcome than changes in cost estimates. Broadly, findings provide support for the cognitive mediation hypothesis of social phobia and point to both outcome cost and outcome probability as potential treatment mech‐ anisms. Findings are discussed in the context of extant theories of social phobia, and directions for fu‐ ture research are proposed.