Date of Award

1-1-1984

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

Abstract

Prior investigations of eye movements to pictured scenes indicate that during the first few moments of viewing there is a rapid shifting of the eye to scene areas that can be reliably identified as informative. Often, as viewing continues, a more deliberate analysis of picture detail is exhibited, with considerably more time spent looking at less informative scene areas. Potentially, variability in viewer arousal may influence this pattern of looking at pictures. Studies of the effects of arousal on perception have suggested that attention narrows with heightened arousal, but have neglected systematic study of eye movement behavior which might help reveal this effect.Thirty-six subjects (30 female) viewed 60 color photographs of real-world scenes for 10 s each, while eye movement behavior and pupil diameter were recorded. Twenty pictures each were viewed while subjects were exposed, in a counterbalanced fashion, to high (100 dBA), medium (75 dBA), and low (50 dBA) intensity broadband noise. No explicit task demands were placed upon the subjects. Each picture was subsequently divided into eight equal-sized regions and an independent group of 72 subjects rank ordered the regions within each picture with respect to the relative amount of information each region conveyed. Analyses of variance were conducted upon number of fixations, fixation duration, interfixation distance, and pupil diameter as a function of judged informativeness of the picture region fixated, viewing time, and noise level in effect when viewed.Although the major determinant of eye movement behavior was the relative informativeness of the eight regions within each pictured scene, arousal (noise intensity) repeatedly moderated the influence of informativeness. It was concluded that increasing viewer arousal resulted in a shift in mode of perceptual processing from an automatic processing of high informative regions to a more controlled processing of less informative picture regions. Pupil diameter increased when subjects were exposed to high intensity noise regardless of the informativeness of regions fixated, demonstrating that the pupillary response reflects viewer arousal independent of changes in effort. However, pupil diameter did correlate with informativeness, indicating that changes in pupil size also reflect expenditure of cognitive effort.

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