Impaired early visual categorization of fear in social anxiety

Abstract

Social anxiety is associated with biased social perception, especially of ambiguous cues. While aberrations in high-level processes, including cognitive appraisal and interpretation of social signals, have been implicated in such biases, contributions of early, low-level stimulus processing remain unclear. Categorical perception is known to be an efficient process to resolve signal ambiguity, and categorical emotion perception can swiftly classify sensory input, \"tagging\" biologically important stimuli at early stages of processing to facilitate ecological response. However, early threat categorization could be disrupted by exaggerated threat processing in anxiety, resulting in biased perception of ambiguous signals. We tested this hypothesis among individuals with low and high trait social anxiety (LSA and HSA), who performed a 2-alternative-forced-choice (fear or neutral) task on facial expressions parametrically varied along a neutral-fear continuum. Clear divergence between the groups emerged in the profiles of reaction time (RT) and early visual response along the neutral-fear continuum. The LSA group exhibited a RT profile characteristic of categorical perception with drastically increased RT from neutral to intermediate (boundary) fear intensities, contrasting monotonous, non-significant RT changes in the HSA group. Neurometric analysis along the continuum identified an early fear-neutral categorization operation (arising in the P1, an early visual event-related potential/ERP at 100 ms) in the LSA (but not HSA) group. Absent group differences in higher-level cognitive operations (identified by later ERPs), current findings highlight a dispositional cognitive vulnerability in early visual categorization of social threat, which could precipitate further cognitive aberrations and, eventually, the onset of social anxiety disorder.