Visual periodicity reveals distinct attentional signatures for face and non-face categories

ABSTRACT Observers can selectively deploy attention to regions of space, moments in time, specific visual features, and individual objects. One level higher, we can also attend to particular high-level categories – for example, when keeping an eye out for dogs while jogging. Here we exploited visual periodicity to examine how the focus of category-based attention serves to differentially enhance and suppress selective neural processing of face and non-face categories. We combined electroencephalography (EEG) with an adaptation of the established Fast Periodic Visual Stimulation (FPVS) paradigm designed to capture selective neural responses for multiple visual categories contained in the same rapid stream of object images (faces and birds in Exp 1; houses and birds in Exp 2). Our key finding was that the pattern of attentional enhancement and suppression for face-selective processing is unique compared to non-face object categories. Specifically, where attending to non-face objects provides a strong boost their selective neural signals during the 300-500ms window, attentional enhancement of face-selective processing is both earlier and comparatively more modest. Moreover, only the selective neural response for faces appears to be actively suppressed when observers attend towards an alternate visual category. These results underscore the special status that human faces hold within the human visual system, and highlight the utility of visual periodicity as a powerful tool for indexing selective neural processing of multiple visual categories contained within the same visual sequence.