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

Abstract

Human faces elicit faster saccades than objects or animals, resonating with the great importance of faces for our species. The underlying mechanisms are largely unclear. Here we test two hypotheses based on previous findings. First, ultra-rapid saccades towards faces may not depend on the presence of the whole face, but the upper face halve containing the eye region. Second, ultra-rapid saccades towards faces (and possibly face parts) may emerge from our extensive experience with this stimulus and thus extend to glasses and masks - artificial features frequently encountered as part of a face. To test these hypotheses, we asked 43 participants to complete a saccadic choice task, which contrasted images of whole, upper and lower faces, face masks and glasses with car images. The resulting data confirmed ultra-rapid saccades for isolated upper face halves, but not for artificial facial features.

Faces in scenes attract rapid saccades

“…We found strong evidence that face- versus inanimate object–directed saccades are preceded by shorter fixations and have higher peak velocity. These results are in line with previous findings on the latency and velocity advantage for saccades directed to isolated faces ( Broda, Haddad, & de Haas, 2022 ; Crouzet et al., 2010 ; Kauffmann, Khazaz, Peyrin, & Guyader, 2021 ; Reppert et al., 2015 ; Xu-Wilson et al., 2009 ; Yoon, Jaleel, Ahmed, & Shadmehr, 2020 ) and show it extends to free-viewing complex scenes, which is marked by visual clutter and the concurrent processing of foveal and extrafoveal input. The concurrent processing of high-level features at both currently foveated and target locations is matching findings from the transsaccadic literature showing that features of the upcoming target can be processed before the saccade is initiated ( Herwig & Schneider, 2014 ; Osterbrink & Herwig, 2021 ; Wilmott & Michel, 2021 ).…”

“…Saccades targeting faces versus inanimate objects were preceded by shorter fixations when controlling for potentially confounding predictors. This is reminiscent of the very low latencies observed for saccades directed to isolated face stimuli ( Broda et al., 2022 ; Crouzet et al., 2010 ; Martin et al., 2018 ). Our results show this effect extends to free-viewing, where extrafoveal targets are processed concurrently with currently foveated targets.…”

Individual differences in looking at persons in scenes

“…Certain semantic categories, such as faces outweigh others in their saliency ( Cerf, Paxon Frady, & Koch, 2009 ; Xu et al, 2014 ). Faces and especially eyes elicit faster saccades than other stimuli ( Broda, Haddad, & de Haas, 2022 ; Crouzet, Kirchner, & Thorpe, 2010 ) and most observers fixate faces within the first two fixations when present in a scene. Consequently, the addition of face detection to low-level saliency models significantly improves gaze prediction ( Cerf, Harel, J., Einhäuser, & Koch, 2008 ).…”

Individual fixation tendencies in person viewing generalize from images to videos

“…Human gaze is particularly attracted by social stimuli, both in static ( End & Gamer, 2017 ) and dynamic scenes ( Rubo & Gamer, 2018 ; Smith & Mital, 2013 ). Faces attract early fixations in static scenes ( Cerf et al, 2009 ) and elicit saccades faster than other semantic objects in saccadic choice tasks ( Broda et al, 2022 ; Crouzet et al, 2010 ). Faces are also highly salient in the context of videos ( Foulsham et al, 2010 ; Klin et al, 2002 ).…”