Changes in response to S+ and S− during acquisition and overtraining of simultaneous discriminations in rats

Abstract

Two experiments with rats investigated learning about S+ and S-during various stages of discrimination training. Transfer tests, in which either S+ or S-was retained, or two new stimuli were presented, were used to assess learning early in acquisition, at criterion, or following overtraining. Both choice and latency measures were used. Results indicated that learning about S+ occurs early in acquisition when noncorrection training is given, and little improvement occurs after that time, at least up to 70 trials of overtraining under present conditions. Learning about S-begins somewhat later in acquisition and continues throughout overtraining. When correction training is used, learning about Soccurs earlier in acquisition, and further learning about both S+ and S-occurs during overtraining.Most theories of simultaneous discrimination learning ha ve ,been more concerned with the rate of discrimination between two stimuli than with possible differences in rate of learning about the two stimuli considered separately. In simultaneous discrimination experiments, the two stimuli to be differentiated are present on every trial. Relative choice of the two stimuli is measured, and the organism is said to have learned the discrimination when it consistently chooses the positive stimulus (S+) over the negative stimulus (S-). Some theories, such as Spence's (1936), make provision for differential growth of approach and avoidance tendencies, but the parameters have rarely been pursued in simultaneous discrimination designs. Sutherland and Mackintosh's theory (1971) places primary emphasis on the growth of attention to the dimensions comprising the stimuli and leaves unspecified rate of development of approach to positive values of those dimensions vs. avoidance of negative values. Some of the relevant literature is reviewed below.Response to S+ and S-in Early Acquisition (presolution Stage) Some early studies with rats provide a small amount of conflicting data (Krechevsky, 1938;McCullogh & Pratt, 1934). In some of these studies it was shown that at least some early learning about reinforcement contingencies took place because acquisition was retarded when the contingencies were reversed. In other studies, no retardation was found. In either event, the reversal method used does not allow a determination of separate response tendencies to S+ and S-, since the reinforcement values of both stimuli were changed at the same time. One set of studies reversed only one stimulus and combined it with a new stimulus (Lashley & Wade, 1946). Greater retardation in learning a discrimination was found when S-was made positive than when S+ was made negative. This result suggests earlier learning about S-than S+, since changing S-was more disruptive. However, the technique of changing a stimulus from positive to negative or vice versa may be unnecessarily complex. A simple technique would be to substitute a new stimulus either for S+ or S-, rather than reversing reinforcement values. Response to S+ and S-at CriterionSeveral studies have show...

The effect of visual deprivation in the rat on transfer effects after form discrimination training

“…The results with regard to overtraining seem to provide indirect support for some of the ideas of Mandler and Goldberg (1975) regarding changes in S+ and S-during (0ver)training. However, the 150 trials of overtraining did not seem to have as systematic or facilitative an effect on performance of visually inexperienced rats as might have been expected (Sutherland & MacKintosh, 1971).…”

String-pulling in the Goffin’s cockatoo (Cacatua goffiniana)

“…As none of the individuals changed their strategy after unsuccessful trials, reliance on visual proximity dominated over any potential short-term learning effect. This may be explained by an overtraining or carryover effect (Díaz-Uriarte, 2002 ; Mandler & Goldberg, 1975 ) from the training phase. The individuals likely learned to predominantly focus on the configuration from the top, rather than paying attention to the arrangement form the starting position.…”

Alleviation of overtraining reversal effect by transient inactivation of the dorsal striatum

“…In the literature, the one condition in which the effect of overtraining seems reasonably reliable is when rats are trained with a large reward in a moderately difficult simultaneous visual discrimination task (Reid, 1953; Pubols, 1956; Capaldi & Stevenson, 1957; Mandler, 1966; Mackintosh, 1969; Sperling, 1970). In our experiment, both stimuli, although highly discriminable, are presented successively.…”