The effects of display size, target eccentricity, and perceptual difficulty on the distribution of attention in the visual field
Anderson, Loy A.
Lane, David M.
Doctor of Philosophy
The operation of distributing attention to regions of the visual field was investigated in order to further understand the role of attention in the perception of visually-presented stimuli. In each of three experiments, a target letter was presented somewhere within a precued region of the visual display. The task was to determine which one of two possible targets had been presented. The size of the to-be-attended region of the display, the degree of target eccentricity within each region, and the perceptual difficulty of the stimulus discrimination were manipulated factorially. There was evidence that subjects were able to distribute their attention to regions of varying size, but that the focus of attention could not be confined within the boundaries of a non-circular display region. The size of the region to which attention was distributed was related to the speed and accuracy of responses to attended stimuli. However, the size of the display did not interact with either perceptual difficulty or target eccentricity. The interpretation that is consistent with these findings is that attention facilitates the localization of a visual stimulus rather than affecting the rate at which a stimulus is processed. Consequently, the operation of localizing a stimulus can occur more efficiently when attention is focused on a smaller region of a visual display than on a larger region.