Influence of visual acuity on monocular face perception and exploration: Evidence from gaze‐contingency

Abstract

Aims/Purpose: The remarkable ability of the human brain to identify faces has traditionally been divided in the scientific literature into relative contribution of an analytical versus a holistic way of processing the visual stimuli. Although the “part‐by‐part” analysis allows identification, previous studies have proven that the ability to perceive all parts in a simultaneous fashion seems to be the key element of what makes observers experts at face identification. Here, we aim to better understand the impact of visual acuity (VA) on the holistic and analytical processing of the face.Methods: We performed face‐matching tasks of unfamiliar faces using a gaze‐contingency approach in 12 normally sighted adults. Three viewing conditions (full view, mask effect, window effect) were simulated while VA was artificially decreased using a blur technique to obtain a linear scale of VA from LogMar 1,3 to 0,3.Results: At the group level, response times and number of fixations in full view, mask effect and window effect remained well preserved at VA as low as LogMar 1,0. Around that level of VA, both time and number of fixations increased with decreasing VA and were higher in the mask condition than in the other conditions.Conclusions: Facial identification performances remain well preserved at low VA. Evolution has allowed the brain to identify faces even if pathologies affecting the visual pathways strongly limit VA. This probably derives from the holistic strategy for face identification and the involvement of brain areas specialized in high level visual processing.