Abstract
Adult face processing is limited by observers' experience – discrimination ability and face-specific behavioral effects are reduced in out-group faces. Nonetheless, other-species faces phylogenetically close to our own (e.g. chimpanzees) are processed by face-specific "holistic" mechanisms (Taubert, 2009). Presently, we asked whether or not the well-known effect of contrast-negation on face recognition (Galper, 1970) was exclusive to human faces or generalized to monkey faces. Negation disrupts face pigmentation substantially (Russell, 2007), allowing us to examine species-specific use of surface cues as a function of extended visual development. We tested adults (N=24) and children between the ages of 3.5-5 years (N=21) on a 4AFC discrimination task. Trials consisted of four same-species faces: Three identical distractors and a non-matching target. Participants identified the target as quickly as possible using a touchscreen. Adults completed this task using four types of stimuli: (1) The original faces, (2) Luminance-negated faces: Reversed contrast but original chroma, (3) Chroma-negated faces: Reversed chroma, but original contrast, (4) Fully-negated faces: Both contrast and chroma negated. Children completed this task using only the original faces and the fully-negated stimuli. Adults were highly accurate in all conditions. Further, adults’ response latencies revealed a main effect of stimulus category (Monkey RTs <Human RTs) and an interaction between luminance and chroma negation, such that the original faces were discriminated more quickly than all others independent of species. Children were also equally accurate across all conditions and displayed the same main effect of species on response time. However, children showed no evidence of a negation effect for either species. Our data thus suggest that human and monkey faces suffer equally from luminance and chroma negation in adult observers, but that children have yet to develop a robust negation effect in early childhood.
Meeting abstract presented at VSS 2012