Thesis (M.Sc.) -- Memorial University of Newfoundland. 1974. / Typescript. Bibliography : leaves 36-42. Also available online.

Thesis (M.A.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Two experiments investigated the effects of pre-receptoral absorption and levels of illumination on colour vision. Simulation filters approximating lens and macular pigment changes were constructed on the basis of previous investigations. Experiment I investigated the effects of these filters on young, normal subject performance. Shifts were found in the direction of ageing populations but not as great as is required. Experiment II investigated the additional effect of reductions in illumination. The two experimental manipulations together account for senile decreases in discrimination at slightly higher levels than previously reported / Arts, Faculty of / Psychology, Department of / Graduate

This study investigated color discrimination as a possible localized function of right or left cerebral hemispheres in humans. Previous studies have shown conflicting results. Studies implicating the left hemisphere have contaminated color discrimination with verbal-symbolic ability. Other studies implicating the right hemisphere emphasized color-matching ability. This study pointed out the importance of response latency as well as accuracy and also the importance of testing the data for meeting the assumptions of the statistical technique utilized. It was concluded that color discrimination is normally a right-hemisphere function in right-handed individuals. Differences in individual ability, although large, were not found to be systematically related to sex or eye dominance, but may be learned individual differences. The study further pointed out the inappropriateness of referring to a major or dominant cerebral hemisphere without stipulating which function is being considered.

This study is an attempt to understand if backgrounds with color impact physiology and the ability of a viewer to see color.

Color vision is widespread in the animal kingdom, and describes the ability to discriminate between objects purely based on the wavelengths that they reflect. Experiments across many species have isolated wavelength comparison in the brain as a computation underlying color vision. This comparison takes place in color opponent neurons, which respond with opposite polarity to wavelengths in different parts of the spectrum. In this work, I explore color opponency in the genetically tractable organism Drosophila melanogaster, where these circuits have only just begun to be described. Using two-photon calcium imaging, I measure the spectral tuning of photoreceptors in the fruit fly and identify circuit mechanisms that give rise to opponency. I find two pathways: an insect-specific pathway that compares wavelengths at each point in space, and a horizontal-cell-mediated pathway similar to that found in mammals. The horizontal-cell-mediated pathway enables additional spectral comparisons through lateral inhibition, expanding the range of chromatic encoding in the fly. Together, these two pathways enable efficient decorrelation and dimensionality reduction of photoreceptor signals while retaining maximal chromatic information. This dual mechanism combines motifs of both an insect-specific visual circuit and an evolutionarily convergent circuit architecture, endowing flies with the ability to extract chromatic information at distinct spatial resolutions.

Thesis (Ph.D.)--Boston University / This study examined the relationship between delay of response in problem-solving and ability to integrate color and form on a perceptual task. It was an attempt to relate a perceptual process to a personality variable, and thus make meaningful certain individual differences in perceiving in terms of more general principles of ego controls. [TRUNCATED]

No description available.

The amenability of various color-controlling algorithms to the real-time operator control of color stimuli was investigated. Mathematical models based on eight color spaces were employed: three uniform color spaces (L*u*v*, L*h*C*, and Y 2.2u' VI), a graphics algorithm (HLS), an opponent color model, the NTSC broadcast signals (YIQ), and two sets of color primaries. Eighty subjects, divided equally among the color spaces, were required to match colors under time-limited conditions. The apparatus employed was a color-manipulation device using LEDs, custom-built in the Displays and Controls Laboratory at Virginia Tech. The device allows for 12-bit resolution on each color channel and higher stability of luminance and chrominance over the short and long term than can be achieved with experimental quality CRTs. / Master of Science

No / Precortical color vision is mediated by three independent opponent or cardinal mechanisms that linearly combine receptoral outputs to form L/M, S/(L+M), and L+M channels. However, data from a variety of psychophysical and physiological experiments indicate that chromatic processing undergoes a reorganization away from the basic opponent model. Frequently, this post-opponent reorganization is viewed in terms of the generation of multiple ¿higher order¿ chromatic mechanisms, tuned to a wide variety of axes in color space. Moreover, adaptation experiments have revealed that the synthesis of these mechanisms occurs at a level in the cortex following the binocular integration of the inputs from each eye. Here we report results from an experiment in which the influence of chromatic adaptation on the perceived visual location of a test stimulus was explored using a Vernier alignment task. The results indicate that not only is positional information processed independently within the L/M, S/(L+M), and L+M channels, but that when adapting and test stimuli are extended to non-cardinal axes, the existence of multiple chromatically tuned mechanisms is revealed. Most importantly, the effects of chromatic adaptation on this task exhibit little interocular transfer and have rapid decay rates, consistent with chromatic as opposed to contrast adaptation. These findings suggest that the reorganization of chromatic processing may take place earlier in the visual pathway than previously thought.