An inexpensive and automated method for presentation of olfactory or tactile stimuli in a two-choice task for rats was implemented with the use of a computer-controlled bidirectional motor. The motor rotated a disk that presented two stimuli of different texture for tactile discrimination, or different odor for olfactory discrimination. Because…

Rat received conditioning based upon a food unconditioned stimulus and then received manipulations designed to reduce the value of that food. The effects of these manipulations were assessed during extinction tests of the conditioned stimuli. (Editor/RK)

Three experiments are reported in which rats first received 50 escapable or inescapable signaled-shock trials. The results of the experiments are discussed in terms of a learned active-inactive predisposition to respond. (Editor/RK)

Rats performed an intermittently reinforced operant response and received periodic presentations of a visual conditioned stimulus (CS) located either very near or far from the operant manipulandum. Findings suggest there are deficiencies in the general accounts of conditioned suppression that stress the motivational or emotional effects of…

Four experiments, all employing the conditioned suppression of licking in thirsty rats, examined the extent to which reinforcement of one component, A, of a compound conditioned stimulus, AB, would "block" conditioning to the other element, B, on the first compound trial. (Editor)

Experimenters in the past have reported that when insulin is used as the unconditioned stimulus (US), rats will learn an aversion to a sodium chloride but not a sucrose solution, whereas with formalin as the US, they will learn an aversion to a sucrose but not a saline solution. The present experiments failed to confirm these findings. (Editor)

These experiments investigate situations in which a negative correlation involves a 24 hour delay between the occurrence of a conditioned stimulus and an unconditioned stimulus; they also investigate the mechanism by which any inhibition so produced might occur. (Author/RK)

Three experiments, employing conditioned suppression in rats, examined the extent to which pretraining on one element of a compound stimulus blocked conditioning to the other element when some feature of the reinforcer was changed on compound trials. (Editor)

The research reported here was directed at evaluating whether or not the effectiveness of a Pavlovian unconditioned stimulus (US) in promoting associative learning is reduced if the US is shortly preceded by another occurrence of the same US. (Author)

Recent data indicate that the form of the conditioned response (CR) may often be substantially influenced by the characteristics of the conditioned stimulus (CS) as well as by those of the unconditioned stimulus (US). Here five experiments examine the influence of CS characteristics on the form of the Pavlovian CR anticipatory to a food US in…

Repeated, isolated presentations of a stimulus typically reduce the subsequent ability of that cue to become an effective conditioned stimulus. This phenomenon is known as the latent inhibition effect. Four experiments investigate this effect. (Editor/RK)

These experiments attempt to optimize the possibility of demonstrating blocking in a taste-aversion paradigm and to elucidate the conditions under which this interference occurs. (Author/RK)

Three experiments carried out second-order Pavlovian conditioning using either similar or dissimilar first-and second-order stimuli. All three experiments were designed to identify the effects of similarity upon conditioning as distinct from its effects upon sensitization or stimulus generalization. (Editor/RK)

Four experiments examined the possibility that the outcome of simultaneous and backward fear conditioning procedures might depend upon the number of conditioned stimulus-unconditioned stimulus pairings. (Editor/RK)

Quantitative analyses of stimulus control and reinforcer control in conditional discriminations and delayed matching-to-sample procedures often encounter a problem; it is not clear how to analyze data when subjects have not made errors. The present article examines two common methods for overcoming this problem. Monte Carlo simulations of…