Stimulus analyzer theory as proposed by Sutherland and Mackintosh (1971) makes the unique prediction that the first-experienced reinforcement schedule will influence resistance to extinction more than subsequent schedules. Results presently reported of runaway acquisition and extinction indicate the opposite: C-P consistently produce substantially…

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…

Presents three experiments that explore whether inescapable shock of long duration and moderate intensity (LoShk) produces an avoidance-escape deficit (called an interference effect) by causing animals to learn to respond less actively or by causing them to learn to be "helpless". (Editor)

Several experiments tested the occurrence of the "Kamin effect", i.e., the deficit in performance of an incompletely learned avoidance task, in terms of discrimination (choice) behavior by rats. (Editor/RK)

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)

Stress facilitates memory formation, but only when the stressor is closely linked to the learning context. These effects are, at least in part, mediated by corticosteroid hormones. Here we demonstrate that corticosterone rapidly facilitates synaptic potentiation in the mouse hippocampal CA1 area when high levels of the hormone and high-frequency…

A delayed matching-to-sample (DMTS) task was used to test several hypotheses about sources of retroactive inhibition (RI) in pigeon short-term memory. (Editor)

Given an opportunity to choose between an immediate, small reward and a delayed, large reward, pigeons may commit themselves to the large reward, but if the choice is encountered they will almost always select the immediate, small reward. This study tested a model, developed by H. Rachlin and his co-workers, concerning some general theories of…

Grant and Roberts found that houselight presented throughout the delay period on a delayed matching-to-sample task caused pigeons to demonstrate a much lower level of accuracy than was found when the delay was spent in darkness. A series of experiments was carried out to examine possible mechanisms responsible for this light-induced retroactive…

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)

To complement investigations of the direct effects of lithium toxicosis on consummatory behavior, these experiments were designed to determine the aftereffects on drinking of exposure to a conditioned stimulus previously paired with lithium. (Author/RK)

In four different experiments, brief illumination of a localized visual stimulus was followed by grain presentation unless the pigeon approached the light. Results indicate that although response-reinforcer relations do play a role, stimulus-reinforcer contingencies are the dominant factor in establishing and maintaining approaches to the…

Investigates the nature of the rhythmic process mediating multiple retention deficits in rats, i.e., whether it was induced by a training procedure or based on a pre-existing physiological rhythm. Also concerns the mechanism of the rhythm's effect on retention performance, whether it affects performance factors per se or the retrieval of prior…