Different Top-Down Goals Modulate Early Stage of Attention Bias: Irrelevant Task Suppresses the N170 of Automatic Attention Allocation to Threat Faces
Abstract Recent research has evidenced that stimulus-driven attention bias for threat can be modulated by top-down goals. However, it remains unclear how different top-down goals affect the early stage of attention processing and its early neural mechanism. We collected electroencephalographic data from 28 healthy volunteers during four inconsistent levels in a modified spatial cueing task according to cue validity and task relevance. Our data revealed that reaction time(RT) to the target in the irrelevant task were much slower than that in the relevant task. In the irrelevant task, we did not find the difference between the RTs to the fearful and neutral face. In the relevant task, we found RTs of fearful face were faster than that of neutral face in valid cue condition(weak inconsistent level), whereas the RTs of fearful face were slower than that of neutral face in invalid cue condition(medium inconsistent level). The ERPs results showed that in relevant task(weak, medium inconsistent levels), fearful face in cue position of the target evoked larger N170 amplitudes than neutral face did, whereas this effect was suppressed in irrelevant task(strong, very strong inconsistent levels). Besides, fearful face in cue position of the target also evoked larger vertex positive potential (VPP) amplitudes than the neutral face did in valid cue condition( weak inconsistent level). These results suggest that irrelevant task may inhibit the early attention allocation to the fearful face. Furthermore, the top-down processing modulates the early attention bias for threatening faces.