Academic journal article The Psychological Record

Cross-Modal Stimulus Class Formation in Rats

Academic journal article The Psychological Record

Cross-Modal Stimulus Class Formation in Rats

Article excerpt

This experiment examined the whole-partial effect of overtraining in concurrent discriminations using two different sensory modality tasks (tactual and visual task) and assessed the effect against single discrimination training in rats. Overtraining facilitated reversals in both Group W, in which rats were given concurrent training on two tasks in the original learning before both tasks were reversed, and Group S, in which rats were trained only on the tactual task before it was reversed. Overtraining retarded reversal in Group P, in which rats were given the same training as in Group Win original learning, but only the tactual task was reversed. After overtraining, Groups W and S reversed more rapidly than Group P. After criterion training, Group P reversed more rapidly than Group W, which reversed more rapidly than Group S. These findings indicate that rats form stimulus classes (i.e., cross-modal stimulus classes) between the discriminative stimuli of two different sensory modalities with the same respons e assignment during overtraining in two concurrent discriminations as well as between the discriminative stimuli of the same sensory modality.

There are many studies on stimulus classes formation in pigeons and rats using a conditioning procedure (Hall, Ray, & Bonardi, 1993), a common coding procedure (Edwards, Jagielo, Zentall, & Hogan, 1982; Urcuioli, Zentall, Jackson-Smith, & Steirn, 1989; Zentall, Urcuioli, Jagielo, & Jackson-Smith, 1989), a whole-partial reversal procedure (Delius, Ameling, Lea, & Staddon, 1995; Nakagawa, 1978, 1986, 1992, 1998; Vaughan, 1988; Zentall, Sherburne, Steirn, Randall, Roper, & Urcuioli, 1992; Zentall, Steirn, Sherburne, & Urcuioli, 1991), and serial reversal procedure (Dube, Callahan, & Mcllvane, 1993; Vaughan, 1988). They make it clear that pigeons and rats have an ability to form stimulus classes or stimulus-stimulus associations between the discriminative stimuli of the same sensory modality, which are not only homogeneous associations (i.e., shape-shape or color-color) but also heterogeneous associations (i.e., shape-color). Thus, a specific question remains. Do rats form stimulus classes or stimulus-stimulus a ssociations between the discriminative stimuli of two different sensory modalities, for example stimulus-stimulus associations between a visual stimulus (i.e., vertical line or horizontal line) and a tactual stimulus (i.e., rough or smooth)?

The categorization processes view (Bhatt & Wasserman, 1989; Fersen & Lea, 1990; Vaughan & Herrstein, 1987) has proposed that a concept comprises stimuli that are bound together by relations that are based solely on perceptual similarity. That is, stimulus classes formation is caused by categorization of stimuli based on simple similarity between stimuli.

Experimental support for these proposals can be found in Vaughan and Herrstein (1987) where pigeons worked on concurrent VI schedules with the alternations signaled by slides either containing trees or not. Responding to the two alternatives was well described by the generalized matching equation with substantial undermatching. Using an adaptation of the matching law, it was estimated that the pigeons were correctly classing 82-95% of exemplars. The matching performance transferred to new exemplars of trees and nontrees with only slight generalization decrement. The pigeons appeared to be discriminating among exemplars even when the alternatives provided equal rates of reinforcement and the average relative performances were close to 50%. (See also Bhatt & Wasserman, 1989, and Fersen & Lea, 1990). The two pairs of stimuli (i.e., vertical-horizontal stripes as visual stimuli and smooth-rough as tactual stimuli) have no simple similarity between them. Thus, it is very difficult for rats to form a visual stimul us-tactual stimulus association on the basis of simple similarity between these stimuli. The expectation according to the categorization processes view based on simple similarity between these stimuli is that rats cannot form cross-modal stimulus classes. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.