Facial expression recognition takes longer in the posterior superior temporal sulcus than in the occipital face area.

Neuroimaging studies have identified a face-selective region in the right posterior superior temporal sulcus (rpSTS) that responds more strongly during facial expression recognition tasks than during facial identity recognition tasks, but precisely when the rpSTS begins to causally contribute to expression recognition is unclear. The present study addressed this issue using transcranial magnetic stimulation (TMS). In Experiment 1, repetitive TMS delivered over the rpSTS of human participants, at a frequency of 10 Hz for 500 ms, selectively impaired a facial expression task but had no effect on a matched facial identity task. In Experiment 2, participants performed the expression task only while double-pulse TMS (dTMS) was delivered over the rpSTS or over the right occipital face area (rOFA), a face-selective region in lateral occipital cortex, at different latencies up to 210 ms after stimulus onset. Task performance was selectively impaired when dTMS was delivered over the rpSTS at 60-100 ms and 100-140 ms. dTMS delivered over the rOFA impaired task performance at 60-100 ms only. These results demonstrate that the rpSTS causally contributes to expression recognition and that it does so over a longer time-scale than the rOFA. This difference in the length of the TMS induced impairment between the rpSTS and the rOFA suggests that the neural computations that contribute to facial expression recognition in each region are functionally distinct.