COLLATERAL BEHAVIOR OF THE PIGEON DURING CONDITIONED SUPPRESSION OF KEY PECKING¹

Abstract

Ethological recording procedures measured collateral behavior in pigeons whose key-pecking performance was suppressed during a tone that ended with unavoidable electric shock. Independent recordings of gross behavior were made by two observers throughout 60-sec intervals immediately before, during, and after tone presentation. Results indicated significant reductions in the frequency of collateral movements and an increase in the time between successive movements during tone presentations. These effects were observed in all subjects, despite differences in the sequential patterns of behavior. Only partial recovery of the behavior evidenced before tone presentation was found during a 60-sec interval following shock. It was concluded that conditioned suppression procedures caused the bird to "freeze" during tone presentation and in this fashion produced a general inhibitory effect on ongoing overt activity, including key pecking.A stimulus that repeatedly precedes an inescapable noxious event can acquire the capacity to reduce the rate of responding maintained by positive reinforcement (Estes and Skinner, 1941). This effect is known as conditioned suppression and has been suggested as a quantitative index of conditioned emotional behavior (Brady and Hunt, 1955).The conditioned suppression effect is frequently explained in terms of the elicitation of conditioned respondents during the pre-shock stimulus. Thus, Brady and Hunt (1955) characterized the conditioned suppression phenomenon as the result of a generalized or nonspecific inhibitory effect of the pre-shock stimulus on all overt behavior. They noted that when a rat trained to press a lever for food is subjected to the Estes-Skinner procedure, the disruption in lever pressing during the pre-shock stimulus is accompanied by characteristic crouching, immobility, and defecation. These reactions were subsumed under the term "freezing" and employed, in part, as evidence for an emotional state. Alternatively, Dinsmoor (1954, 1955 and Weiskrantz (1968) Weiskrantz (1968) proposed that movements that minimize the noxious qualities of a stimulus such as electric shock may increase in frequency during a pre-shock stimulus and physically prevent the subject from maintaining the baseline behavior. Thus, according to this view, to suggest that the pre-shock stimulus controls a conditioned emotional state that disrupts the rate of large classes of behavior through an inhibitory influence may be inappropriate or, at best, incomplete.The present study was designed to assess the behavioral changes produced by the EstesSkinner procedure in pigeons trained to peck a key under a schedule of food presentation. Specifically, the study was to determine whether the conditioned suppression phenomenon is characterized by a reduction in the rate of all ongoing behavioral movements (i.e., freezing) or whether, alternatively, subjects engage in other movements that increase in frequency during a pre-shock stimulus and prevent a maintenance of baseline responding. In the present research, ...

IN COMPATABILITY BETWEEN THE PIGEONS' UNCONDITIONED RESPONSE TO SHOCK AND THE CONDITIONED KEY‐PECK RESPONSE1

“…Bolles based his theory on a review of the literature involving rats. The evidence presented in this paper as well as by Smith and Keller (1970), Gustavson, et al, (1971), Stein, Hoffman, and Stitt (1971) and otlhers suggest the point is equally well taken withi pigeons.…”

The effects of intensities of shock and thirst on licking conditioned suppression

“…The data indicate that one cannot always equate suppression with freezing, or that there is no specific motorrespondent classically conditioned to the CS. The present data, then, do not agree with the conclusion drawn by Stein et al (1971) from their pigeon's pecking suppression experiment that the freezing is the interfering incompatible respondent. It should be noted, however, that they used only a single level of shock intensity.…”

“…First, Dinsmoor (1954Dinsmoor ( , 1955 and Weiskrantz (1968) pointed out the possibility that the CS would lead to an increase in the frequency of other behavior (operants and respondents) incompatible with the baseline response. Brday and Hunt (1955) and Stein, Hoffman, and Stitt (1971), on the other hand, suggested that " freezing " was the respondent incompatible with the baseline response. Perhaps the best and only experiment, in which systematic measurements of actual incompatible response or responses covarying with suppression were made, is the pecking suppression experiment with pigeon performed by Stein et al (1971).…”

“…Brday and Hunt (1955) and Stein, Hoffman, and Stitt (1971), on the other hand, suggested that " freezing " was the respondent incompatible with the baseline response. Perhaps the best and only experiment, in which systematic measurements of actual incompatible response or responses covarying with suppression were made, is the pecking suppression experiment with pigeon performed by Stein et al (1971). No such attempt has been made with other species and in other situations.…”

Rat behaviors during unsignaled avoidance and conditioned suppression training

“…We found only two experiments addressed to this question. Hoffman and Barrett (1971) and Stein, Hoffman, and Stitt (1971) found reductions in food-reinforced responding and other overt activities of pigeons during the CS. A parallel experiment with an avoidance baseline has not been done and was the primary purpose of this experiment.…”