Date of Award

Winter 1981

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

Abstract

In order to assess whether pigeons acquire simple and contingent chromatic aftereffects, four White Carneaux pigeons were trained to discriminate between colored and achromatic slides: Right and left key-pecks were reinforced following exposure to colored and achromatic slides, respectively. The chromatic set included slides of six different hues, added sequentially. Behavior on the first day each new color was added and on two transfer tests involving novel stimuli indicated that a 'chromaticity' concept had been acquired by all four birds.

In Experiment II, an attempt was made to demonstrate the McCollough effect (ME). In five procedures, various conditions known to produce a maximally strong ME in humans were arranged for the pigeons. In each case, various slides, including achromatic ME test stimuli, were presented following adaptation. As compared with control achromatic slides, no increase in right key-pecks following test stimuli was observed. Thus, no evidence for the ME was obtained.

In Experiment III, evidence of simple chromatic adaptation in the pigeons was obtained. Six-min components alternated in which the experimental chamber was illuminated with either a green floodlamp or a "white" bulb. The proportion of right key-pecks following achromatic slides was much higher during green than during white components, indicating that the achromatic slides appeared more like the chromatic slides.

Because the chromatic and achromatic slides differed in film type (Kodachrome, Panatomic-X), some dimension other than the chromaticity of the object photographed might have controlled the birds' behavior. In Experiment IV, two tests separated these two potential sources of stimulus control by presenting "achromatic" Kodachrome slides and Panatomic-X slide with spots of color. Film type, not object chromaticity, was found to control the birds' behavior at this time. Spectral analyses of the two types of slides showed that they differed chromatically, and a further test revealed that this difference controlled the birds' behavior: When color-correcting green filters of varying saturation were sandwiched with Panatomic-X slides, the proportion of right key-pecks increased as a function of filter saturation. The results of this experiment demonstrate the difficulty of "communicating" with non-verbal creatures and make the results of Experiment II difficult to interpret.

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