Date of Award:

1981

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Psychology

Advisor/Chair:

Carl D. Cheney

Abstract

One of the most rapidly expanding areas of research in psychology has been poison-based aversion learning (PBAL). The PBAL paradigm typically involves: exposing an animal to a novel substance; inducing illness following ingestion of that substance; and then providing access to the substance at a later time. The initial reaction to the novel substance is generally to reduce consumption, a finding labeled neophobia. The reduction of substance intake on test day is called learned aversion.

Following demonstrations of cue-to-consequence specificity (i.e., the differential associability of some stimuli with certain consequences) in PBAL research with rats, recent research has focused on PBAL by avians. Such research has been instigated by speculation that avians might be specially adapted to better associate visual rather than flavor stimuli with illness. Studies to determine the relative salience of visual or flavor cues in avian PBAL have reported contradictory findings. A number of methodological differences exist between these studies including differences in stimulus intensity and type, duration between conditioning and assessment, and method of assessment. The current series of experiments made several methodological improvements to clarify the issue of cue to consequence specificity in PBAL with avians. Three experiments with pigeons as subjects are reported.

The first experiment equated (scaled) stimulus intensity across different sense modalities by equating neophobic responses to various concentrations of salt, sour, and red water.

The second experiment determined the extended effects of the illness-inducing stimulus alone on fluid consumption by pigeons in a restricted access to water environment.

The third experiment was based upon results from the first two experiments and assessed aversion, at two different post-injection times, to one of two concentrations of either salt, sour, or red water CSs. In addition, a compound (flavor plus color) conditioning group was employed.

Aversion was a function of flavor or color stimulus intensity. No differences were observed in degree of aversion demonstrated by groups receiving stimuli equated for initial suppression. Evidence for overshadowing or potentiation was not found.

The results support the position that neither flavor or color stimuli are necessarily the most salient in avian PBAL.

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