Evaluating equivalence relations in rats using an olfactory matching-to-sample procedure

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
L. Brooke Poerstel (Creator)
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Mark Galizio

Abstract: Equivalence classes can be characterized as groups of stimuli which control responding based on relations among members of the class, rather than absolute stimulus features such as shape, size, or color. Formation of equivalence classes often includes conditional discrimination training, which establishes contingency relations between physically dissimilar, arbitrary stimuli using a Match-To-Sample (MTS) paradigm. If, through the conditional discrimination training, the arbitrary stimuli become members of predetermined equivalence classes, then four untrained properties of equivalence classes (identity or reflexivity, symmetry, transitivity, and equivalency) should also emerge during test configurations. Unlike humans, evidence of responding characteristic of equivalence class formation in nonhuman animals is rarely, if ever, found. Regardless, classification of environmental stimuli based on abstract, relational features may be a fundamental aspect in learning and adaptation, as well as a possible indication of nonhuman symbolic behavior. The equivalence model also provides a parsimonious account of the often complex social and communicative behaviors observed in nonhuman animals in natural settings. Perhaps traditional laboratory equivalence procedures require modification such that these behaviors may be more readily observed in nonhuman subjects. The current paper evaluated whether rats could demonstrate (1) acquisition of conditional discriminations, both identity and arbitrary, within the training framework and (2) relational responding in the presence of novel testing configurations (emergence of generalized identity matching, symmetry, transitivity, and equivalence relations) through a modified MTS procedure using olfactory stimuli and class-specific reinforcers. Three experiments were conducted to evaluate generalized identity MTS (Experiment 1), arbitrary MTS and emergent equivalence (Experiment 2), and training experience effects on emergent equivalence performance (extensive identity MTS pre-training versus no identity MTS pre-training, Experiment 3). Subjects, 11 Male HSD rats, were trained to retrieve reinforcers from cups of scented sand, which served as the stimuli throughout the experiment. Nine subjects were trained identity MTS discriminations during Experiment 1. Five of the nine demonstrated convincing evidence for generalized identity matching. The same five animals were then trained arbitrary MTS discriminations and given emergent equivalence tests during Experiment 2. Four of the five Experiment 2 subjects performed above chance during equivalence tests. Experiment 3 consisted of arbitrary MTS training with two naïve subjects that had no identity MTS experience. One Experiment 3 subject received an emergent equivalence test, but did not perform above chance levels. The results of the three experiments suggest that olfactory stimuli and class-specific reinforcers allow for transfer of responding during both generalized identity and emergent equivalence tests. The exact effect of pre-training on emergent equivalence performances is still unclear, as the results of Experiment 3 are currently inconclusive.

Additional Information

A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Arts
Language: English
Date: 2009
Rats -- Research

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