An investigation of perceptual load, aging, and the functional field of view
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A common metaphor for visual attention is the spotlight (Posner, 1980). It follows from the spotlight metaphor and other similar models (e.g., zoom-lens model; Eriksen and Yeh, 1985) that attention can, according to task-demands, be constricted into a focused beam (i.e., analogous to selective attention) or dilated to encompass a larger breadth (i.e., analogous to divided attention). It is currently unclear how variations in perceptual load of a display affect the FFOV. Lavie (1995; Lavie et al., 2004) proposed that the critical determinant of selective attention (i.e., a constriction of the FFOV) was the perceptual load imposed by the taskselective attention is a necessary outcome of limited perceptual processing capacity. Age-related differences in perceptual processing capacity (e.g., Maylor and Lavie, 1998) may then explain observed age-related differences in FFOV size (e.g., Ball, Beard, Roenker, Miller, and Griggs, 1988). The current study examined how perceptual load and aging affected the FFOV. Younger and older participants viewed brief displays in which they engaged in two tasks: the first task was a perceptual load manipulation, while the second task was a measure of the FFOV. Multiple measures of peripheral task performance suggest that the size of the FFOV for older adults was significantly reduced by increasing perceptual load and this effect of load was greater with increasing distance from fixation. As predicted from the perceptual load model, when perceptual load of the task increased, perceptual sensitivity for the distant peripheral task decreased for older adults. This decrease was greater when the task was farther from fixationindicative of a shrinking spotlight. However, for younger adults, increasing load did not affect peripheral task performance. This age-related difference may be attributable to older adults reduced perceptual processing capacity. The current results support the notion that older adults reduced perceptual processing capacity may be one cause of their reduced FFOV. Limitations of the current study as well as future research are discussed.