How does an animal conceal itself from visual detection by other animals? This review
paper seeks to identify general principles that may apply in this broad area. It considers …

The visibility of an isolated simple stimulus is known to depend on its contrast. However,
when such a stimulus is surrounded by other geometrically-simple stimuli, its perceived …

Simple everyday tasks, such as visual search, require a visual system that is sensitive to
differences. Here we report how observers perceive changes in natural image stimuli, and …

The cone contrasts carrying different dimensions of color vision vary greatly in magnitude,
yet the perceived contrast of color and luminance in the world appears similar. We examined …

We are studying how people perceive naturalistic suprathreshold changes in the colour,
size, shape or location of items in images of natural scenes, using magnitude estimation …

The human visual system combines contrast information from the two eyes to produce a
single cyclopean representation of the external world. This task requires both summation of …

Major Professor: Brian P. Dyre, Ph. D. ii AUTHORIZATION TO SUBMIT THESIS This thesis of
William A. Schaudt, submitted for the degree of Master of Science with a major in …