Foveal analysis and peripheral selection during active visual sampling

Significance Picking up visual information from our environment in a timely manner is the starting point of adaptive visual-motor behavior. Humans and other animals with foveated visual systems extract visual information through a cycle of brief fixations interspersed with gaze shifts. Object identification typically requires foveal analysis (limited to a small region of central vision). In addition, the next fixation location needs to be selected using peripheral vision. How does the brain coordinate these two tasks on the short time scale of individual fixations? We show that the uptake of information for foveal analysis and peripheral selection occurs in parallel and independently. These results provide important theoretical constraints on models of eye movement control in a variety of visual-motor domains. Human vision is an active process in which information is sampled during brief periods of stable fixation in between gaze shifts. Foveal analysis serves to identify the currently fixated object and has to be coordinated with a peripheral selection process of the next fixation location. Models of visual search and scene perception typically focus on the latter, without considering foveal processing requirements. We developed a dual-task noise classification technique that enables identification of the information uptake for foveal analysis and peripheral selection within a single fixation. Human observers had to use foveal vision to extract visual feature information (orientation) from different locations for a psychophysical comparison. The selection of to-be-fixated locations was guided by a different feature (luminance contrast). We inserted noise in both visual features and identified the uptake of information by looking at correlations between the noise at different points in time and behavior. Our data show that foveal analysis and peripheral selection proceeded completely in parallel. Peripheral processing stopped some time before the onset of an eye movement, but foveal analysis continued during this period. Variations in the difficulty of foveal processing did not influence the uptake of peripheral information and the efficacy of peripheral selection, suggesting that foveal analysis and peripheral selection operated independently. These results provide important theoretical constraints on how to model target selection in conjunction with foveal object identification: in parallel and independently.