Exploring the relationship between anxiety and processing capacity for threat detection

Cognitive models suggest that anxiety is associated with the presence of a highly sensitised threat detection mechanism which, once activated, leads to the automatic allocation and focusing of attention on the source of threat (review by Bar-Haim, Lamy, Pergamin, Bakermans-Kranenburg & Ijzendoorn, 2007). Previous studies have only ever considered the detection of singleton threat targets in anxiety. The threat detection system should also be configured to rapidly detect signs of impending danger in situations where there is a possibility of multiple threats. Given multiple threats, it is unclear whether a more advantageous strategy for threat detection in anxious individuals is to localise and focus attention on one threat stimulus or to distribute attention widely (see Eysenck, Derakshan, Santos & Calvo, 2007). To address this theoretical question, we conducted a reaction time redundant signals study in which participants were asked to indicate the presence or absence of an angry or happy target face in displays containing no targets, one target or two targets. In all conditions, the task was to detect the presence of at least one target. We used measures of processing capacity (e.g., capacity coefficient, Miller and Grice inequalities; see Wenger & Townsend, 2000) to assess whether, at all time points, the fastest RTs in the redundant target condition (e.g., two target condition) could be predicted from the fastest RTs in the single target conditions. Eye-movements were also measured during the study. Significant correlations showed that anxiety was associated with increased processing capacity for threatening faces but only at early time points in target detection. The results also demonstrated that significantly fewer eye-movements were made to targets when anxiety was high. The data are consistent with anxiety influencing threat detection via a broadly tuned attentional mechanism.