Human Spontaneous Gaze Patterns in Viewing of Faces of Different Species

Abstract

Human studies have reported clear differences in perceptual and neural processing of faces of different species, implying the contribution of visual experience to face perception. Can these differences be manifested in our eye scanning patterns while extracting salient facial information? Here we systematically compared non-pet owners' gaze patterns while exploring human, monkey, dog and cat faces in a passive viewing task. Our analysis revealed that the faces of different species induced similar patterns of fixation distribution between left and right hemi-face, and among key local facial features with the eyes attracting the highest proportion of fixations and viewing times, followed by the nose and then the mouth. Only the proportion of fixation directed at the mouth region was species-dependent and could be differentiated at the earliest stage of face viewing. It seems that our spontaneous eye scanning patterns associated with face exploration were mainly constrained by general facial configurations; the species affiliation of the inspected faces had limited impact on gaze allocation, at least under free viewing conditions.

Differential Gaze Behavior towards Sexually Preferred and Non-Preferred Human Figures

“…Therefore, it is unlikely that visual distinctiveness of the waist-hip region in young female figures could solely account for this increase in gaze distribution. Recent gaze pattern studies in face or body perception also suggest that local image regions with high image salience (based on the calculation of local image physical properties) are not correlated with the gaze distribution in viewing images with high biological relevance (Birmingham et al, 2009;Dahl et al, 2009;Guo et al, 2010) (also see our analysis in Figure 2). Hence the gaze distribution within a human figure is more likely to be dependent upon the amount of available taskrelevant information contained within each figure region, rather than constrained by their simple physical properties.…”

“…Any difference in fixation distribution and viewing time from zero means that this particular figure feature attracted more or less fixations than predicted by a uniform viewing strategy (Dahl, Wallraven, Bulthoff, & Logothetis, 2009;Guo, Tunnicliffe, & Roebuck, 2010 …”

Dog owners show experience-based viewing behaviour in judging dog face approachability

“…Furthermore, as the same facial feature across faces of different species often vary in size (e.g., dogs usually have larger noses than humans), the proportion of the area of a particular facial feature relative to the whole image was subtracted from the proportion of fixations directed at that feature in a given trial. Any difference in fixation distribution from zero means that this particular facial 8 region attracted more or less fixations than predicted by a uniform looking strategy (Guo, Tunnicliffe, & Roebuck, 2010).…”

“…Whilst determining fixation allocation within key internal facial features (i.e. eyes, nose, and mouth), a consistent criterion was adopted to define boundaries between local facial features for different faces (for details see Guo, Tunnicliffe, & Roebuck, 2010). Specifically, the 'eye' region included the eyes, eyelids, and eyebrows; the 'nose' or 'mouth' region consisted of the main body of the nose (glabella, nasion, tip-defining points, alar-sidewall, and supra-alar crease) or the 'mouth' and immediate surrounding area (up to 1°).…”

“…At neural processing level, the 'face-sensitive' N170 event-related potential (ERP) component elicited by human faces peaked 10 ms 4 earlier than that elicited by monkey faces (e.g., Carmel & Bentin, 2002;Rousselet, Mace, & Fabre-Thorpe, 2004). Furthermore, one recent eye-tracking study further compared non-pet-owners' spontaneous gaze distribution in the viewing of human, monkey, dog and cat faces, and observed that the proportion of fixations directed at the mouth region was species-dependent (fewer fixations at the dog or cat mouth) and could be differentiated at the earliest stage of face viewing (Guo, Tunnicliffe, & Roebuck, 2010).…”