Idiosyncratic Eye-Movement Patterns to Faces Are Associated With Differences in Neural Processing: Evidence From Behavioral and Event-Related Potential Responses.

Although faces are homogeneous stimuli, individuals adopt different eye-movement patterns when looking at them. Do such differences in eye movements reflect distinct patterns of neural processing of faces? We conducted two experiments to investigate how face-viewing preferences affect face-sensitive event-related potentials (ERPs). In both experiments, participants were separated into two groups: an upper-focused group who fixated mainly on the eyes of faces and a lower-focused group who fixated more on the nose and mouth. Participants then completed two fixation number-controlled blocks in Experiment 1 or two fixation duration-controlled blocks in Experiment 2, in which the initial fixation location was restricted to the left eye or the nose. In both fixation number-controlled and duration-controlled blocks, the upper-focused group performed better and elicited a larger P1-to-N170 peak-to-peak amplitude for the eye-fixation condition than the nose-fixation condition. In contrast, the lower-focused group performed evenly and elicited comparable P1-to-N170 amplitudes between fixation conditions. In addition, the P1 component was larger for the nose-fixation condition than the eye-fixation condition, and this difference was bigger for the lower-focused group than the upper-focused group. On the other hand, the P1 appeared to have no relation to behavioral performance. These findings show how individual differences in fixation patterns for faces map to differences in neural processing of those faces, and in turn provide evidence for the intricate relationship between sensory and neural processing of visual information.