Date of Award
Doctor of Philosophy (PhD)
Dr. B.G. Galef
Exteroceptive-cue-toxicosis associations are usually difficult to produce and generally less robust than flavour-toxicosis associations. The following series of experiments investigates the paradoxical enhancement of aversion conditioning to exteroceptive cues induced by the presence of a novel flavour at the time of exteroceptive-cue-toxicosis conditioning.
It was found that this flavour facilitation effect is due, in part, to the operation of a mechanism that directs subjects' attention to stimulus attributes of ingesta (Chapter 3). Further experiments suggested that the attentional mechanism is not robust enough to facilitate visual-cue-aversion conditioning over long delays (Chapter 4) and that, consistent with an attentional interpretation, only certain stimuli were subject to the operation of the attentional mechanism (Chapter 5). Apparently rats are more likely to treat certain stimuli as attributes of food objects and these stimuli are more readily associated with toxicosis.
Adaptive-evolutionary accounts that dichotomize stimuli into those that are and those that are not associable with toxicosis or theories that suggest that all exteroceptive cues are contraprepared to be associated with toxicosis cannot account for the present finding of graded exteroceptive-cue-toxicosis conditioning with distance from the food object. The experiments of this thesis suggest that stimulus salience is not an inflexible characteristic of the stimulus itself. Rather, it is suggested that stimulus salience varies as a function of several factors amongst which the type of reinforcement and time of onset of reinforcement, the presence of other stimuli, the animal's past experience with the stimuli and the relation of the stimuli to the food object appear to play central roles.
Dalrymple, Andrew, "Role of Attention in Exteroceptive-Cue-Aversion Learning" (1980). Open Access Dissertations and Theses. Paper 612.