No abstract

This study tested how human faces affect object-based attention (OBA) through two online experiments in a modified double-rectangle paradigm. The results of Experiment 1 revealed that faces did not elicit the OBA effect as non-face objects, which was caused by a longer response time (RT) when attention is focused on faces relative to non-face objects. In addition, by observing faster RTs when attention was engaged horizontally rather than vertically, we found a significant horizontal attention bias, which might override the OBA effect if vertical rectangles were the only items presented; these results were replicated in Experiment 2 (using only vertical rectangles) after directly measuring horizontal bias and excluding its influence on the OBA effect. This study suggested that faces cannot elicit the same-object advantage in the double-rectangle paradigm and provided a method to measure the OBA effect free from horizontal bias.

Orienting network is an important part of attention system and it includes two major tasks: visual orienting and visual search. For these two tasks, typically developed group shows similar neural mechanisms. However, from a perspective of attention to non-social information, different behavioral patterns were observed between visual orienting and visual search in autism spectrum disorder (ASD) group.Regarding visual orienting, the consensus is that ASD individuals are intact in attentional shift but have difficulty in attentional disengagement; however, this conclusion is still controversial. Regarding visual search, ASD individuals have superior search ability, but its time sequence and reasons deserves further exploration. Future studies should identify the hemispherical symmetry of ASD individuals in visual orienting task, the underlying mechanisms of visual search advantage, and the relationships between visual orienting and visual search in ASD populations.

Numerous studies on face processing have revealed their special ability to affect attention, but relatively little research has been done on how faces guide spatial attention allocation. To enrich this field, this study resorted to the object-based attention (OBA) effect in a modified double-rectangle paradigm where the rectangles were replaced with human faces and mosaic patterns (non-face objects). Experiment 1 replicated the typical OBA effect in the non-face objects, but this effect was absent in Asian and Caucasian faces. Experiment 2 removed the eye region from Asian faces, but still found no object-based facilitation in the faces without eyes. In Experiment 3, the OBA effect was also observed for faces when the faces disappear a short period before the responses. Overall, these results revealed that when two faces are presented together, they do not exert object-based facilitation regardless of their facial features such as race and the presence of eyes. We argue that the lack of a typical OBA effect is due to the filtering cost induced by the entire face content. This cost slows down the response when attention shifts within a face and results in the absence of object-based facilitation.