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Abstract: Behavioral characteristics and neural correlates of decision making can be identified and compared across different object categories. In a 2AFC task of preference between two faces, one’s gaze becomes biased towards the to-be-chosen face before conscious decision, called “Gaze cascade effect”(1)(2). By manipulating the gaze pattern via a positive feedback loop between gaze & exposure, the conscious preference decision can be manipulated (ibid). The gaze cascade turned out not limited to face stimuli. It occurs generally across various stimulus types, including geometric figures and commercial products, and in multiple-alternative choice situation. Yet, it is semi-specific to preference task - it is either attenuated or absent in other tasks such as objective judgment on facial roundness. One may speculate on an evolutionary scenario where the fundamental orienting mechanism led to such a gaze cascade loop, which in turn provided a basis of implicit social interactions. The gaze-exposure dynamics no doubt leads to, and affected by, memory, but how exactly is controversial. The literature has split into two principles; novelty and familiarity. Our results suggest that cumulative experience leads to preference for familiar faces, whereas that for novel natural scenes (and mixed in geometric figures)(3). Together with fMRI results(4), it indicates distributed, separate neural correlates of preference decision. However, another line of studies examining implicit “leakage of attractiveness” from unattended to attended objects indicates some similarities across these object types. Finally, we found that high/low AQ (Autism Quatient) subjects behaved differently in a task not to look at eyes in faces. A new technique to track mutual gaze in live interpersonal interactions revealed even more decisive differences and identified subtypes in the ASD group. The results indicate substantial differences in their gaze patterns, pointing to uniquely emotional and social aspects of face perception.
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References (1) Shimojo S., et al.: Gaze bias both reflects and influences preference. Nat. Neurosci., 6, 1317-1322, 2003 (2) Simion C., Shimojo S.: Early interactions between orienting, visual sampling and decision making in facial preference. Vis. Res., 46, 3331-3335, 2006 (3) Park J., et al.: Roles of familiarity and novelty in visual preference judgments are segregated across object categories. Proc. NAS, doi: 10.1073/pnas.1004374107, 2010. (4) Kim, H. Kim, H., Adolphs, R., O'Doherty, J. P. and Shimojo, S. Temporal isolation of neural processes underlying face preference decision. Proc. Nat. Acad. Sci., 104, 18253-18258, 2007. (5) Shimojo et al. VSS’13; Gharib et. al, VSS’14; Wang et al., VSS’14; Wang et al., VSS’15.