Thesis (Ph. D.)--University of California, San Diego, 1998. / Vita. Includes bibliographical references (leaves 233-244).

Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--New England College of Optometry, 2009. / Includes bibliographical references (p. 41-45).

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 137-142).

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published_or_final_version / Psychology / Master / Master of Philosophy

No description available.

Although it is well known that the pupil responds dynamically to changes in ambient light levels, the results from this dissertation show for the first time that the pupil also responds dynamically to changes in spatially distributed attention. Using a variety of orientating tasks, subjects alternated between focusing attention on a central stimulus and spreading attention over a larger area. Fourier analysis of the fluctuating pupil diameter indicated that: 1) pupil diameter changed at the rate of attention variation, dilating with broadly spread attention and contracting with narrowly focused attention, and 2) pupillary differences required changes in attentional spread; there were no differences in pupil diameter between sustained broad and sustained spread attention. Given that broadly spread attention increases the relative activation of large receptive fields and narrowly focused attention increases the relative activation of small receptive fields (Balz & Hock, 1997), the results of this study indicate that these attentional effects on receptive field activation can be mediated by changes in pupil diameter. That is, under broad attention, the corresponding pupillary dilation observed would increase spherical aberration, blurring the image thereby reducing high spatial frequency information and decreasing the activation of relatively small cortical receptive fields compared to relatively large receptive fields. This increased perception of low spatial frequencies would be beneficial in cases where attention is spread over a large area. Alternatively, under narrow attention the resulting pupillary constriction reduces spherical aberration sharpening the image and preserving high spatial frequency information resulting in a relatively increased response of small receptive fields. / by Lori B. Daniels. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.