Date of Award:

1990

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Psychology

Advisor/Chair:

Carl D. Cheney

Abstract

In two experiments, second-order conditioned taste aversion techniques were employed to develop aversions in rats, with a geotactic-excitation procedure as the independent variable. Periodic tilting of an experimental apparatus resulted in angular orientation changes of all subjects located within compartments of the chamber. The effect was excitation of geotactic behaviors, expressed as locomotor activity within the confines of these compartments.

In the first experiment, two groups of rats (n = 6) were exposed to experimental protocols which were identical with the exception of the independent variable. Three conditioning trials were presented, separated by five to seven days, within which strychnine injections preceded LiCl injections by 15 minutes. A treatment trial was presented five days following the last drug pairing, in which a novel flavor was available in lieu of tap water. Immediately following the 10-min water-access period, an injection of the CS-drug was administered. Testing for evidence of second-order CTA was conducted via presentation of the flavored solution on the fifth day following treatment. statistically significant results were obtained in terms of Learned Aversion Ratios and CTA Suppression Ratios. A second experiment was conducted in an attempt to isolate the influence of the excitation procedures with other drug-pairings. Five groups of rats (n = 6 in each group) were run in which hypertonic saline was paired with LiCl, strychnine, or hypertonic saline. Combinations of saline and the US-drugs were tested with and without the excitation procedures. A no-injection group (n = 6) received exposure to the flavor stimulus followed only by the excitation procedure. Results obtained on the Learned Aversion Ratios were statistically significant and in the predicted direction. The excitation group in which saline had been paired with LiCl showed a significant aversion ratio compared to the appropriate control groups, the Saline-Saline Group and the No-Injection Group. The Saline-Strychnine Excitation Group also showed a significant Learned Aversion Ratio compared to its respective control group and to the No-Injection Excitation Group.

The implications of these results for such issues as stimulus equipotentiality, avfail, and research methodology and CTA research in general may provide additional foundations for future research in this experimental area.

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