DIFFERENTIAL AUTOSHAPING TO COMMON AND DISTINCTIVE ELEMENTS OF POSITIVE AND NEGATIVE DISCRIMINATIVE STIMULI¹

Abstract

The learning by hungry pigeons of a discrimination between two successively presented compound visual stimuli was investigated using a two-key autoshaping procedure. Common and distinctive stimulus elements were simultaneously presented on separate keys and either followed by food delivery, S+, or not, S-. The subjects acquired both between-trial and within-trial discriminations. On S+ trials, pigeons pecked the distinctive stimulus more than the common stimulus; before responding ceased on S-trials, they pecked the common stimulus more than the distinctive one. Mastery of the within-display discrimination during S+ trials preceded mastery of the between-trials discrimination. These findings extend the Jenkins-Sainsbury analysis of discriminations based upon a single distinguishing feature to discriminations in which common and distinctive elements are associated with both the positive and negative discriminative stimuli. The similarity of these findings to other effects found in autoshaping-approach to signals that forecast reinforcement and withdrawal from signals that forecast nonreinforcement-is also discussed.Much of what is known about the way organisms learn successive discriminations has come from the key pecking of different visual patterns by hungry pigeons (see Terrace, 1966 for a general review). Ordinarily, the shared and unique aspects of those visual stimuli are simultaneously projected on a single stimulusresponse device. Recently, however, differential responding to the common and distinctive elements of compound visual stimuli has been measured either by projecting the stimulus elements upon different response keys (Jenkins, 1973;Jenkins and Sainsbury, 1969, 1970;Sainsbury, 1971) or by rapidly alternating those elements upon a single manipulandum (Farthing, 1971). Use of these methods permits the direct measurement of selective stimulus control, rather than relying upon more indirect measures such as transfer or generalization tests (see Sutherland and Mackintosh, 1971 Most of this recent work has been concerned with discriminations based upon a single distinguishing element or feature. In the so-called "feature-positive" (FP) condition, a unique stimulus element is correlated with reinforcer presentation. For example, S+ might be composed of a white dot and a red dot projected on a small dark field and S-might be composed of two white dots. In the "featurenegative" (FN) condition, the stimulus-reinforcer relations of the two-dot displays would be reversed. Despite the fact that FP and FN discriminations involve the same physical stimuli, the former discrimination is mastered much more rapidly than the latter, which may not be mastered at all (e.g., Jenkins and Sainsbury, 1969).A clue as to why the formation of a successive discrimination may depend upon assigning the distinctive feature to S+ or S-trials is revealed by examining the portion of the displays to which subjects respond. In the case of the FP discrimination, responding comes to be directed toward the distinctive feature on S+ trial...

Monitoring same/different discrimination behavior in time and space: Finding differences and anticipatory discrimination behavior

“…The spatial location of pigeons' pecks has also been used to study other kinds of discrimination behavior. For example, pigeons selectively peck at the diagnostic feature in a feature-positive discrimination (Jenkins & Sainsbury, 1970;Wasserman & Anderson, 1974) or at category-specific information in a categorization task (Allan, 1993;Dittrich, Rose, Buschmann, Bourdonnais, & Güntürkün, 2010).…”

The Role of Observing and Attention in Establishing Stimulus Control

“…Jenkins and Sainsbury (1969) divided their key into four independent sectors or quadrants, each of which could be pecked separately (see also Farthing, 1971;Hearst, 1975;Jenkins & Sainsbury, 1970;Sainsbury, 1971;Wasserman & Anderson, 1974). On any given trial, one sector was left blank, but either a circular spot, 0.3 cm in diameter, or a star of the same size was projected on each of the other three.…”

Association of conditioned stimuli during serial conditioning by pigeons

“…Briefly, this procedure exploited the fact that the pigeon's autoshaped keypecking is directed primarily toward only one localized stimulus even though more than one stimulus may be presented at the moment (Wasserman, 1974;Wasserman & Anderson, 1974;Wasserman & McCracken, 1974). Using such multiple stimulus compounds as CS2, it was then possible to determine by the pigeon's choice of pecking keys whether the subject was anticipating the location of the upcoming CSI.…”