When faces signal danger: event-related potentials to emotional facial expressions in animal phobics.

摘要

Attentional bias research indicates that specific phobics prioritize the processing of disorder-relevant stimuli, although the time course of attentional allocation to the phobic threat remains unclear. The present study employed event-related potentials (ERPs) to investigate whether a processing bias also exists towards specific facial expressions that are able to signal potential phobic cues in the environment. Fifteen women with snake phobia and 15 healthy controls performed an attention-shifting task in which angry, fearful, disgusted and neutral faces were presented as emotional cues. ERP to facial expressions and reaction times to target stimuli were collected during the task. The P200 amplitude was significantly lower in phobics than in controls, specifically in response to facial expressions of fear and disgust. Such reduction in cortical activity may reflect reduced processing associated with rapid cognitive avoidance. Such an avoidance response would not be determined by the threat value of the face stimuli per se, but rather by the ability of fearful and disgusted faces to avert attention by signaling a possible phobic threat in the surrounding area. In addition, phobics showed relatively greater positivity to negative than neutral facial expressions in the later processing stages, indicating a general hypervigilant processing mode.