Mapping the binocular visual field for a target embedded in a regular background.

The binocular functional visual-field, which is the area around the fixation point within which a target can be detected, was mapped, for two subjects, using a peripherally presented target in a regular background. The field boundaries were very irregular, there were regions of insensitivity within the field areas, and there were differences between the subjects. It was suggested that the irregular boundary and areas of insensitivity may have important implications for mathematical models of visual search. Individual visual-field characteristics may partly account for the difficulty experienced by some people in locating targets even after repeated scanning.