Differential conditioning as a function of exposure time to discriminative and nondiscriminative cues preceding response

Abstract

Five groups of rats received differential conditioning to large and small reward in a straight runway. Three groups were confined to startbox for 0, 2, or 8 sec prior to the opportunity to traverse the runway, with no preresponse discriminative cues to signal reward magnitude until admission to the runway. Two additional groups received the discriminative cues for 2 or 8 sec while confined in the startbox. All Ss learned the discrimination, though the sharp depression in performance to S-found in certain other studies failed to appear. Discriminative cue presentation in the startbox did not influence performance. Together, these facts suggest that preresponse cues only influence a frustrative depression to S-, and that for unknown reasons such a depression failed to appear in this study. Startbox confinement depressed performance to both rewards, with longer durations producing greater depressions.It is common in the area of differential conditioning to find that speed of approach to a small reward (S-) in one situation (e.g., a black runway) is depressed when Ss experience a large reward (S+) in a second situation (e.g., a white runway). This phenomenon has been termed a "negative contrast effect" (NeE) . Studies by Ludvigson and Gay (1967) and Peckham and Amsel (1967) have been instrumental in determining that the mode of presentation of the discriminative cues is important in the development and magnitude of the NeE. These studies indicated that depression of performance to Sthat was especially pronounced in the start measure was displayed by Ss that started from a common neutral startbox. When different startboxes (that matched the color of the alley they preceded) or a transparent start door were used, performance to S-was much less depressed. Thus, it would appear that giving a differential cue (Le., a cue signaling the impending reward magnitude) prior to opportunity for the instrumental response can reduce the NeE that is typically observed in the traditional latency measures. A study reported by Davis, Gilbert, and Seaver (1971) was consistent with these data and further suggested that, given enough time in the presence of the cues, all discrimination disappears . *This work was supported in part by a National Aeronautics and Space Administration Traineeship to the first author, and by U. S. Public Health Service Gmnt MH13314 and a gr.mt from the Texas Christian University Research Foundation to the second author. tThis paper is based upon portions of a dissertation submitted to the Graduate School, Texas Christian University, in partial fulfillment for the requirements for the PhD degree.The present experiment was designed to assess further, in an instrumental differential conditioning task, the effect of variation in amount of exposure to discriminative cues prior to opportunity for the response. Second, the effect of variation in startbox confinement time without discriminative cues present was investigated. METHOD SubjectsThe Ss were 90 experimentally naive female albino rats purchased from the Char...

Differential conditioning as a function of surgical anosmia

“…Davis and Ludvigson (1974) have recently proposed a two-component model of differential conditioning. According to this model, differential responding may result from: (1) nonemotional processes such as differential habit or incentive formation, and (2) an overlay of frustration that may accompany the basic discrimination.…”