Allan R. Wagner

Negative patterning in classical conditioning: Summation of response tendencies to isolable and configurai components

Six rabbits were given classical eyelid discrimination training involving “negative patterning,” i.e., the reinforced presentation of two isolable cues, A+ and B+, and the nonreinforced presentation of their compound, AB—. The basis for discriminative responding which was thereby produced was evaluated by additionally reinforcing a third single cue, C+, and testing the responding to the novel compounds AC and BC as well as the responding to AB, A, B, and C. Although there was less responding to the nonreinforced compound than to any of the single cues, there was significantly more responding to the novel compounds, AC and BC. The results are consistent with the view that component response strengths summate to determine compound responding, but that there are functional, configurational components relatively unique to a stimulus compound.

CS habituation produces a “latent inhibition effect” but no active “conditioned inhibition”

Abstract The effects of nonreinforced, preconditioning exposures to a CS were investigated in two experiments involving Pavlovian eyelid conditioning in the rabbit. Experiment 1 replicated the often-reported consequent retardation in appearance of conditioned responding, or “latent inhibition effect” (e.g., Lubow & Moore, 1959 ; Siegel, 1969 ). Experiment 2 employed identical training conditions but evaluated whether or not the prehabituated CS would also serve as a “conditioned inhibitor” (Pavlov, 1927) . The results indicated that the latent inhibition effect is not the result of the acquisition of active, response-inhibiting properties by the CS, but may be better accounted for in terms of an attentional decrement.

Context-sensitive elemental theory

My theories of associative learning, like those of N. J. Mackintosh and almost all learning theorists, have employed elemental representations of the stimuli involved. We must take notice when two important contributors to elemental theory, J. M. Pearce and W. K. Estes, find sufficient problems with the theory type to cause them to defect from it. I will describe some of the essential problems, concerning the substantial influence of context on learning and retrieval, characterize the different responses of Pearce and Estes, and, then, propose a variation on a recently developed elemental model that was similarly inspired. The resulting elemental theory has a close quantitative relationship to the “product-rule” of Estes and D. L. Medin, and may help us to rationalize how the same formal experimental design can sometimes produce results that favour the configural interpretation of Pearce and at other times the elemental interpretation of R. A. Rescorla and A. R. Wagner, as these have often been pitted against each other.

Startle responsiveness after habituation to different intensities of tone

The likelihood of startle response to different intensities of tone (96, 102, 108, 114, and 120 dB) was evaluated in rats, before and after a series of exposures to either 108- or 120-dB tones. Responsiveness following habituation was less at each test intensity for Ss exposed to 120-, as compared to 108-dB tones. These results were contrasted with other reports which have led to the potentially misleading generalization that habituation is faster or more pronounced, the weaker the stimulus intensity.

Situational cues and correlation between CS and US as determinants of the conditioned emotional response

Administering unsignaled USs during daily CER training sessions interfered with CER conditioning, as has frequently been reported. This effect was reduced, however, when additional daily sessions were administered during which Ss were simply exposed to the experimental environment in the absence of the CS and US. The results indicate that S’s treatment with respect to “situational” cues is important in the determination of CS-US contingency effects, and are in agreement with recent formulations of Wagner (in press, a) and Rescorla (in press) which emphasize that the degree of conditioning to a CS depends upon the associative strength of the constellation of cues in which the CS is imbedded during training.

Backward conditioning to a CS following an expected vs. a surprising UCS

Rabbits were trained in eyelid conditioning with a “backward” arrangement of unconditioned stimulus (UCS) followed by conditioned stimulus (CS). When such a CS was tested alone it was observed to produce substantial conditioned responding if the UCS had been arranged to be “surprising” during the backward pairings, but not if it had been arranged to be “expected.” The comparisons were made in a within-subjects design where the surprisingness of the UCS on the different pairing occasions was manipulated by preceding the UCS by discriminative CSs which were otherwise either never followed by the UCS (CS−) or consistently followed by the UCS (CS+). The results may have implications for the nonmonotonic course of responding seen during backward conditioning, as a UCS is at first surprising, but then expected on the basis of contextual cues.

Development of context-specific tolerance to morphine: support for a dual-process interpretation.

Four experiments were concerned with the development in rats of context-specific tolerance to the sedating and analgesic effects of morphine. Experiment 1 was conducted to assess the temporal course of activity changes and analgesia consequent to acute morphine administration. Experiments 2, 3, and 4 were conducted to assess the development of context-specific morphine tolerance in the two measures under different conditions of pairing of morphine with a distinctive environment. In support of a dual-process model (postulating both a general tendency for conditioned diminution of unconditioned responding and a more restricted influence of the development of specific conditioned compensatory responses), tolerance was observed in both measures, but evidence of conditioned compensatory response was found only in the activity measure. The differential evidence of conditioned compensatory response in the two measures was interpreted as consistent with the fact that the activity measure showed a biphasic unconditioned response in Experiment 1 whereas the analgesic measure did not.

A comparison of the Rescorla-Wagner and Pearce models in a negative patterning and a summation problem

In two experiments, we examined two related conditioning problems previously investigated by Red-head and Pearce (1995a) and Pearce, Aydin, and Redhead (1997). Experiment 1 involved an A+, B+, C+, AB+, AC+, BC+, ABC2 discrimination. The Rescorla-Wagner model predicts that response to AB, AC, and BC will be greater than that to A, B, and C at asymptote, whereas the Pearce model makes the opposite prediction. In Experiment 2, we investigated the responding to a novel ABC compound in groups trained with either A+, B+, C+ or AB+, AC+, BC+. The Rescorla-Wagner model predicts greater response to ABC in the group trained with A+, B+, C+ than in the group trained with AB+, AC+, BC+, whereas the Pearce model makes the opposite prediction. In contrast to the findings of Redhead and Pearce (1995a) and Pearce et al. (1997) in pigeon autoshaping, our findings in rabbit eyelid conditioning support the Rescorla-Wagner model.

Modulation of a discrete Pavlovian conditioned reflex by a putative emotive Pavlovian conditioned stimulus

Three experiments showed the modulation of a rabbit eyeblink conditioned response (CR) to a Pavlovian conditioned stimulus (CS) by 30-s stimuli (A & B) that had been differentially paired with paraorbital shock. The CS (Y) was a 1,050-ms cue that had been paired with paraorbital shock outside A or B. In testing, the amplitude of CRs was greater when Y was presented within A than within B. Differential modulation occurred whether shock in A had been preceded by another 1,050-ms cue, X(AX+,BX-;Experiment 1) or not (A+B-;Experiment 2). Experiment 3 compared the technique of Experiment 1 (AX+) with that of Experiment 2 (A+) and found the latter to be advantageous for facilitation of CRs to Y by A. These data are consistent with the predictions of a model of Pavlovian conditioning (AESOP, Wagner & Brandon, 1989) that distinguishes between emotive and sensory conditioning as did Konorski (1967).

Evaluation of Blocking and Conditioned Inhibition to a CS Signaling a Decrease in US Intensity

Two experiments employing a conditioned emotional response procedure with rats evaluated the associative tendencies acquired by a target CS when a compound of that stimulus and another CS was reinforced by a low-intensity US whereas the latter CS alone was reinforced by a higher intensity US. Experiment 1 involved a blocking sequence in which the element and compound trials occurred in successive phases, followed by eventual testing of the responding to the target CS alone. Less evidence of excitatory conditioning was observed than in a comparison group which had the element and compound paired with the same low-intensity US. Experiment 2 included contemporaneous differential reinforcement of the element and compound CSs and periodic summation tests in which the target CS was compounded with another independently trained CS. Clear evidence was obtained of the development of inhibitory tendencies by the target CS. The results are consistent with the predictions of the Rescorla-Wagner model and are discussed in relation to the several determining assumptions of the model.