Miguel P. Eckstein, Professor
时间： 2013-07-03 16:00 - 18:00
地点： 哲学楼103
When viewing a human face people often initially look towards the eyes. A prominent idea holds that these fixation patterns arise solely due to social norms. Here, I will propose that this behavior can be explained as an adaptive brain strategy to learn eye movement plans that optimize performance in evolutionarily important perceptual tasks (Sensory Optimization Theory). First, I will show that humans move their eyes to points of fixation that maximize perceptual performance determining the identity, gender, and emotional state of a face. These optimal points of fixation, which vary moderately across tasks, are correctly predicted by a rational Bayesian ideal observer that integrates information optimally across the face but is constrained by the decrease in resolution and sensitivity from the fovea towards the visual periphery. A model that disregards the foveated nature of the visual system and makes eye movements to the regions/features with the highest discriminative information fails to predict the human fixations. Second, I will show that this initial optimal point of fixation generalizes across cultures (Caucasians vs. East Asians). Third, I will present evidence suggesting that there is some individual variability in the preferred points of fixation with the majority of humans looking near the eyes while a smaller group looking closer to the tip of the nose. These systematic differences persist over time and also correspond to individual variations in the points of fixation that maximize perceptual performance. Together, our results reveal that initial eye movements to faces, which are fast ( ~ 150-200 ms) and automatic, uncover sophisticated neural computations and a synergy between the face recognition mechanisms and the eye movement system in order to optimize accuracy in an evolutionary important task such as face recognition.2013-07-03
2013-07-03