The attentional bias in blood phobia: An ERP study of task-switching

Previous behavioral and ERP studies demonstrated reliable attentional biases towardsfear-related cues in animal phobics, by showing facilitated attention and/or difficulty indisengagement from threat. In contrast, such effects have not been consistently reportedfor blood phobics. This study aimed at investigating the attentional bias in blood phobiaby overloading the executive system, thus creating competition between the processingof task-relevant and fear-related stimuli. Twenty-two blood phobics and 20 healthycontrols underwent a modified task-switch paradigm with an alternating runs procedure(AABB). In addition to the change of task (classification of letters vs. digits), there was achange of background, showing distracting emotional contents (mutilations, humanattacks, or neutral). Reaction times and accuracy were recorded for 600 successive trialsalong with ERPs to the onset of the background pictures. Results showed that phobicswere less accurate in the switch trials when the previous trial displayed a mutilationcompared to a neutral picture, suggesting a difficulty in disengagement from fear-relatedcontents. Both groups showed lower P3amplitudes in the switch trials when the previoustrial displayed a mutilation compared to a neutral picture, indicating lower attentionalresources allocated to the task. These data indicate that attentional bias can be reliablyshown in blood phobics when the executive control is overloaded. Moreover, as pre-viously shown, evidence is provided for the presence of a stimulus-specific bias towardsblood-related stimuli