Failure to block control by a relevant stimulus

Abstract

Pigeons were trained to depress a treadle in the presence of a discriminative stimulus, either a tone or illumination of red houselights, in order to obtain access to grain or avoid electricshock. In avoidance training, the auditory discriminative stimulus yielded faster acquisition than did the visual one. In appetitive training, the visual discriminative stimulus yielded faster acquisition than the auditory one. Experiments 2 and 3 used these stimuli in Kamin's (1969) blocking design. In Experiment 2, when the pigeons were trained to depress a treadle in the presence of tone to obtain grain and then red light was added as the redundant stimulus, the light acquired stimulus control over treadlepressing; blocking was not observed. In Experiment 3, when the pigeons were trained to depress a treadle in the presence of red light to avoid electric shock and then tone was added as the redundant stimulus, the tone acquired stimulus control over treadlepressing. Again, blocking was not observed. The implications of these results for several models of stimulus control are discussed. 183It has been demonstrated in several paradigms that the experimenter's choice of the reinforcer determines which element of a compound conditioned stimulus or discriminative stimulus will exert the stronger control over responding, that is, there will be a stimulus-reinforcer interaction. One stimulusreinforcer interaction was observed by Foree and LoLordo (1973), who trained groups of pigeons to depress a treadle in the presenceof a compound auditoryvisual discriminative stimulus either to avoid electric shock or to obtain grain. After the pigeons were performing well, the individual elements of the compound stimulus, red houselight and a pure tone, were presented separately to assess their control of treadlepressing. In the test, the tone controlled much more responding than did the red houselight in the shock avoidance condition, but the red light controlled more responding than did the tone in the appetitive condition. Thus, the tone was the dominant stimulus in the avoidance condition, but the red light was the dominant stimulus in the appetitive condition.Kamin (1969) found that, for rats in a conditioned emotional response (CER) procedure, the occurrence of stimulus dominance following compound training could be predicted on the basis of the rates of acquisition in independent groups conditioned to the separate elements. One group of rats conditioned rapidly

Selective Associations Produced Solely With Appetitive Contingencies: The Stimulus‐reinforcer Interaction Revisited

“…In addition, it should be noted that selective associations involving a tone and light may be more constrained in pigeons than in rats. They could not be reversed by a blocking procedure (Kamin, 1969) in pigeons (Lo-Lordo, Jacobs, & Foree, 1982), but could be blocked in rats (Schindler & Weiss, 1985). CONCLUSION The present experiment was formulated on the basis of the confounding effect of the physical nature of the reinforcer-related events (food vs. shock) presented in TL and the resulting affective value that would have been conditioned to the TL compound in the LoLordo (1973), Shapiro et al (1980), and Schindler and Weiss (1982) studies of selective association.…”

Blocking a Selective Association in Pigeons

“…Although Schindler and Weiss (1985) were able to block this selective association in rats, LoLordo, Jacobs, and Foree (1982) were not able to block it in pigeons. Despite pretraining with the contingency-disadvantaged element, food training produced visual control and shock-avoidance training produced auditory control in LoLordo et al's pigeons.…”

“…When this pretraining preceded compound-stimulus training, control was now auditory in pigeons that treadle pressed for food and was visual in pigeons that avoided shock. Previous attempts at blocking this selective association were unsuccessful in pigeons (LoLordo, Jacobs, & Foree, 1982) but were successful in rats (Schindler & Weiss, 1985). Experiment 2 established that selective associations can be blocked in pigeons when the procedures that were effective with rats were systematically replicated.…”

“…As a first step in resolving whether the conflicting results of Schindler and Weiss (1985) and LoLordo et al (1982) represent a true species difference, the procedures that successfully blocked the selective association in rats should be systematically replicated (Sidman, 1960) with pigeons. As yet, a stimulusreinforcer interaction has not been reported for pigeons following compound-stimulus training with multiple schedules of the type employed by Weiss (1982, 1985) with rats.…”

“…LoLordo, 1973, andLoLordo et al, 1982, used discrete-trials training with their pigeons. ) Prior to attempting to block a selective association in pigeons through pretraining with procedures that blocked this type of association in rats (Schindler & Weiss, 1985), it was necessary to determine whether a selective association would be obtained in pigeons given (a) compound S D discrimination training with the multiple schedules used by Weiss (1982, 1985) with rats and (b) stimulus parameters that emulated those used by LoLordo et al (1982) with pigeons. Therefore, in Experiment 1 two groups of pigeons were trained with multiple schedules.…”