Conditioning-induced attentional bias for face stimuli measured with the emotional Stroop task

People with anxiety disorder display attentional bias toward threat-related objects. Using classical fear conditioning, the authors investigated the possible source of such bias in normal participants. Following differential fear conditioning in which an angry face of either male or female (conditioned stimulus: CS+) was paired with mild electric fingershock (unconditioned stimulus: US) but the angry face of the other gender and all other facial expressions unpaired (CS-), an emotional Stroop task was administered. In the Stroop task, participants were required to identify the color of the facial stimuli (red, green, blue, or yellow). Response latency was significantly longer for the CS+ angry face than the other unpaired facial stimuli (CS-). Furthermore, this acquired attentional bias was positively correlated with the level of trait-anxiety measured before the conditioning and the degree of self-reported aversiveness of the US. Our results demonstrated that attentional bias could be induced in normal individuals through a simple associative learning procedure, and the acquisition is modulated by the level of trait anxiety and the level of perceived fear of the aversive US.