The authors review the literature on the 2 main models of the placebo effect: expectancy theory and classical conditioning. A path is suggested to dissolving the theoretical impasse that has long plagued this issue. The key is to make a clear distinction between 2 questions: What factors shape placebo effects? and What learning mediates the…

In four conditioned taste aversion experiments with rats as subjects, the effects of extinguished or pre-exposed flavors on retardation and summation tests was compared. Experiment 1 showed that when steps were taken to ensure similar exposure to the target flavor in all conditions, acquisition after pre-exposure and reacquisition after extinction…

Operant and classical conditioning are major processes shaping behavioral responses in all animals. Although the understanding of the mechanisms of classical conditioning has expanded significantly, the understanding of the mechanisms of operant conditioning is more limited. Recent developments in "Aplysia" are helping to narrow the gap in the…

After extinction of fear to a Pavlovian conditional stimulus (CS), contextual stimuli come to regulate the expression of fear to that CS. There is growing evidence that the context dependence of memory retrieval after extinction involves the hippocampus. In the present experiment, we examine whether hippocampal involvement in memory retrieval…

There is a growing body of evidence that the hippocampus is critical for context-dependent memory retrieval. In the present study, we used Pavlovian fear conditioning in rats to examine the role of the dorsal hippocampus (DH) in the context-specific expression of fear memory after extinction (i.e., renewal). Pre-training electrolytic lesions of…

Tests the hypothesis that there should be an early age range during which inhibiting and facilitating sets do not result in appropriately differential behavior, and that at a subsequent age, there should occur differentiation of GSR conditioning rate as a function of the differential sets. (Author/SDH)

This paper reviews several issues regarding one- versus two-factor theories of learning. First, the traditional distinctions between classical and operant conditioning are presented. This includes both theoretical and experimental contrasts. Second, empirical evidence in support for a one-factor theory is examined. Numerous research studies…

The following experiments are an attempt to clarify the role of learned safety by investigating the applicability of the concept of conditioned inhibition to a taste-aversion procedure and by differentiating its effects fromthose of latent inhibition. (Author)

The paper identified some of the major elements of political learning and suggests some of the conceptual links among these. The basic assumption of this paper is that the several existing approaches to learning and development can account for a significant portion of political learning. A selective picture of concepts and empirical knowledge…

The results of this study suggested that size change may contribute to the forgetting of events occurring late in development, but that neurological immaturity may underly the forgetting of earlier events. (Editor/RK)

Three experiments examined predictions generated by incorporating a common-elements account of stimulus generalization within the Rescoral-Wagner model of conditioning. (Editor)

There has been considerable interest lately in cases where instrumental conditionability appears to depend on the reinforcer used. Here the effects of Pavlovian conditioned stimuli (CSs)on golden hamster behaviors was observed. The intent was to see whether previously reported differences among the behaviors produced by food reinforcement and…

In three experiments, it was demonstrated that human newborn heart rate level can be reliably modified through classical conditioning procedures. Findings support the idea that early learning may occur under a variety of conditions and different theories may account for the results. (Author/SB)

Effects of repeated administration of cocaine to animals behaving under operant contingencies have depended on when the drug is given. Moderate doses given presession have generally led to a decrease in the drug's effect, an outcome usually referred to as tolerance. When these same doses have been given after sessions, the usual result has been no…

This article provides a selective review and integration of the behavioral literature on Pavlovian extinction. The first part reviews evidence that extinction does not destroy the original learning, but instead generates new learning that is especially context-dependent. The second part examines insights provided by research on several related…