Behavior Oriented Vision: Functional Field of View and Processing Resources

Abstract

Peripheral vision performance was examined under free eye movement in natural behavior. As the target, a small spot of light was presented spatially and temporally at random in actual driving. The subjects' task was to make detection response orally during driving. The reaction time and the eye movements were measured. It was clearly shown that, with the increase of situational demands, reaction time becomes longer, and response eccentricity becomes shorter. The latter indicates the narrowing of the functional field of view. In addition it was found that these two are negatively correlated. The result was further confirmed in cases when subjects responded without eye movements. Furthermore, it was found that latency of eye movements is larger in more demanding situations. This suggests that processing around each fixation point is deeper. There seems to be a kind of trade-off between depth and width of processing in the functional field of view. It was suggested that the decrease of peripheral vision performance was due to optimization of allocation of processing resource for coping with demands, and necessity of field experimentation was briefly discussed.