Context as a conditional cue in operant discrimination reversal learning.

Animal Learning & Behavior

Curran

Russell

1988

Self Cite

Four experiments were performed to determine the stimulus characteristics that favor the development of conditional stimulus control in the single reversal paradigm with pigeon subjects. In Experiment 1, pigeons were trained on a successive discrimination between tone frequencies ranging from 350 to 3500 Hz in a particular houselight context condition (houselight-on or -off). The subjects then were trained on the reversal of the tone discrimination in the alternative context. Subsequent tone-frequency generalization testing in the two contexts indicated that they had failed to gain conditional control over the pigeons' discriminative performance. Such control was obtained in Experiment 2, in which the two problems were alternated daily for 32 sessions of training. The gradients then peaked at the appropriate S+ value in each context. In Experiment 3, the key colors (blue vs. red) served as contexts while pigeons learned a successive discrimination in which the discriminative cues were houselight-on versus houselight-off conditions. This was followed by a reversal of the discrimination in the alternative key-color context condition. The key colors were effective conditional cues in this situation. In a previous experiment (Thomas, McKelvie, & Mah, 1985), key color had been ineffective as a conditional cue when the discriminative cues were lines superimposed on the colored background. In Experiment 4, key color was effective when the color and lines were presented on a single key as in the earlier experiment, but were sequenced such that the onset ofthe key color preceded and then overlapped the presentation of the lines. We concluded that conditional discriminations are easiest for pigeons when visual cues are used, but the conditional and discriminative cues must be presented in such a way that they do not combine to form a psychological compound.A typical procedure for studying conditional discrimination learning is to use a background stimulus to indicate the significance of the discriminative stimuli. Thus, in a classic experiment, Lashley (1938) trained rats to select an upright rather than an inverted triangle when the stimulus cards had plain backgrounds and to choose the inverted triangle when the backgrounds were striped. Thomas, McKelvie, Ranney, and Moye (1981) developed a variation of this general procedure, called the single reversal paradigm, in which training on one of the two component problems is completed before training on the reversal problem is initiated. In particular, their procedure begins by training pigeons on a successive discrimination, for example, between two key colors, in the presence of a particular environmental context, such as houselight-on (HL). When the discrimination is mastered after several sessions, the pigeons are then trained on the reversal of the discrimination in the alternative context (houselight-off, HL). Later, retention is assessed via a wavelength generalization test in extinction, with the two contexts alternating in blocks of test trials. The result is that t...

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confidence: 91%

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confidence: 99%

Factors affecting conditional discrimination learning by pigeons: II. Physical and temporal characteristics of stimuli

Animal Learning & Behavior

Curran

Russell

1988

Self Cite

“…Thomas, McKelvie, and Mah (1985) found that the auditory component of HL T played no role in the effectiveness of the compound . They also showed that striped versus plain walls were effective conditional cues, whereas background key color did not gain conditional control over a line angle discrimination in the single reversal paradigm.…”

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confidence: 97%

Conditional discrimination learning by pigeons: The role of training paradigms

Goldberg

1985

Bull. Psychon. Soc.

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Three groups of pigeons (n = 8) learned a successive discrimination, 538-nm S+ versus 576-nm S-, in one context, say , houselight and tone, and the reversal in another context, say , dark and noise. In Group 1, the single reversal paradigm was used ; for Group 2, the problems alternated daily; and for Group 3, they alternated minute by minute. Wavelength generalization gradients obtained in both contexts revealed conditional control by context, which was weakest in Group 3.Conditional discrimination learning refers to a situation in which the (positive or negative) value of a particular stimulus depends on the other stimulus or stimuli with which it is combined. Pigeons typically learn conditional discriminations in operant free-response situations only with great difficulty and after extensive training (Boneau & Honig, 1964;Richards, 1979). In a study by Thomas, McKelvie, Ranney , and Moye (1981), however, such learning was achieved very rapidly. Pigeons first acquired a successive wavelength discrimination and then its reversal, each in a different physical context (e.g. , houselight and tone , HL T, dark and noise, HL N). The subjects were then tested for generalization in each context, and every gradient peaked at the appropriate S + value, that is, that of the S + trained in that context.Both the procedure and the conditional stimuli used by Thomas et al. (1981) differ from those previously used , and which of these factors accounts for the results that were obtained needs to be determined. Thomas, McKelvie, and Mah (1985) found that the auditory component of HL T played no role in the effectiveness of the compound . They also showed that striped versus plain walls were effective conditional cues, whereas background key color did not gain conditional control over a line angle discrimination in the single reversal paradigm. They suggested that pigeons may use global visual cues to identify the place in which food is obtained and may be predisposed to associate such place cues with the learning that occurred in those locations.The present study investigates the temporal factors that may affect operant free-response conditional discrimination learning. With regard to the alternation of training conditions, the single reversal paradigm is at one end of a continuum. At the other end is the typical procedure in which the cues alternate on a minute-by-minute basis (cf. Boneau & Honig, 1964;Richards , 1979). Intermediate between these extremes is conditional serial discrimination reversal learning (CSDR ) as used by Thomas and McKelvie (1982). In their study, a wavelength discrimiRequests for reprintsshouldbe addressed to David R. Thomas, Department of Psychology, Campus Box 345, University of Colorado. Boulder. CO 80309. nation and its reversal were presented on alternate days, with a different line angle accompanying each problem. The birds learned the conditional relationship, and after approximately 30 days of training, they began each session by responding appropriately even before the first reinforcer had bee...

“…Indeed, one might have anticipated a difference in the opposite direction , given the finding that discriminative stimulus control decreases with the passage of time after thecompletion of training (see Kraemer , 1984;Thomas & Lopez, 1962;Thomas et al, 1985). The best explanation of the differences in the slopes of the gradients is that when the houselight is off, the colored keylight illuminate s the entire experimental chamber (however dimly); thus, the subjects are exposed to the key colors regardless of the direct ion in which they are facing.…”

Section: Resultsmentioning

confidence: 99%

The role of response directedness in discriminative and conditional stimulus control

Curran

1988

Bull. Psychon. Soc.

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Six pigeons were trained to press a treadle for variable-interval reinforcement when a blue light was present on the response key; a red light signaled extinction. Subsequently the birds were trained on the reversal of this discrimination. During initial training the houselight was off in the operant chamber; during reversal training it was on. The subjects learned the discrimination problems, although they performed substantially more poorly than they do when the keypeck response is used . Wavelength generalization testing in extinction with the two house light conditions alternating in blocks of trials revealed that the houselight cues had gained conditional control over discriminative responding; the gradients peaked at (or near) the appropriate S+ values in each context. Thus the directedness of the response affects discriminative stimulus control but not conditional stimulus control.In operant conditioning experiments with pigeon subjects, it is common practice to employ visual discriminative stimuli projected on the response key. Thus the discriminative cue is localized, rather than global, and it occurs at the site of, and therefore is contiguous with, the response. Additionally, the response of pecking is part of the normal feeding repertoire of the subject. All of these factors, in combination with the pigeon's excellent vision, may contribute to the high level of discriminative stimulus control typically gained by on-key discriminative cues.A conditional stimulus is one that serves in a hierarchical relationship to discriminative cues, indicating their significance. Thus conditional stimuli are indirectly related to behavior, in comparison with discriminative stimuli , whose relation to behavior is more direct. An example of a conditional stimulus is the houselight in the operant chamber: when it is on, a vertical line on the key is S+ and a horizontal one is S-; when it is off, the reverse is true. In this case the conditional cue is global and diffuse, but on-key conditional stimuli, such as colored lights, may also be used . Thomas , McKelvie, and Mah (1985) reported that training a vertical-horizontal discrimination in one houselight condition followed by the reversal of this discrimination in the alternative houselight context led the houselight condition to acquire conditional control over the birds' discriminative performance, whereas (in a different group of subjects) different key colors (red and blue) on which the lines were projected were ineffective as conditional cues . Perhaps stimuli at which responding is physically directed are most likely to acquire a discriminative (i.e., direct) rather than a conditional (indirect) role . In the present study we inquired whether the formation of a conditional relationship between conditional and discriminative cues would be faciliRequests for reprints should be addressed to David R. Thomas , Department of Psychology, Campus Box 345, University of Colorado, Boulder , CO 80309. tated by the use of discriminative cues toward which responding is direc...