Faces in scenes attract rapid saccades

Abstract

During natural vision the human visual system has to process upcoming eye movements in parallel to currently fixated stimuli. Saccades targeting isolated faces are known to have lower latency and higher velocity, but it is unclear how this generalizes to the natural cycle of saccades and fixations during free-viewing of complex scenes. To which degree can the visual system process high-level features of extrafoveal stimuli when they are embedded in visual clutter and compete with concurrent foveal input? Here, we investigated how free-viewing dynamics vary as a function of an upcoming fixation target, while controlling for various low-level factors. We found strong evidence that face- vs. object-directed saccades are preceded by shorter fixations and have higher peak velocity. Interestingly, the boundary conditions for these two effects are dissociated. The effect on fixation duration was limited to small saccades following the trajectory of the preceding one, early in a trial. This is reminiscent of a recently proposed model of saccade-related retinotopic shifts of attention. The effect on saccadic velocity, however, extended to very large saccades and increased with trial duration. These findings strongly suggest that multiple, independent mechanisms interact to process high-level features of extrafoveal targets and modulate the dynamics of natural vision.

Quick, eyes! Isolated upper face regions but not artificial features elicit rapid saccades

“…Faces also attract more and longer fixations than other semantic categories ( Linka & de Haas, 2020 ; Xu, Jiang, Wang, Kankanhalli, & Zhao, 2014 ) or body features ( Broda & de Haas, 2022b ). When present in a scene, most observers perform a saccade to a face early during exploration ( Cerf, Harel, Einhäuser, & Koch, 2008 ) and with higher velocity compared to inanimate objects ( Borovska & de Haas, 2022 ).…”