Hernan I. Savastano

Learn More
Twenty-four college students participated in an experiment with stimulus compounds. Subjects learned to discriminate color stimuli that correlated with varying probabilities of reinforcement. Reinforcement consisted of points. For all subjects, two colors signaled a .80 reinforcement probability, and two others signaled a .20 probability. For(More)
Four experiments using rats as subjects investigated the claim of Williams (1996) that cue competition results from an associative acquisition deficit, rather than a performance deficit. In Experiment 1, extinction of an overshadowing stimulus following overshadowing treatment increased responding to the overshadowed stimulus, thereby replicating prior(More)
The effectiveness of a stimulus as a conditioned reinforcer depends on the temporal context of reinforcement, that is, the overall rate of reinforcement in the situation. The dominant view has been that context determines the learned value of a stimulus directly, according to delay-reduction theory. By contrast, the contextual choice model (CCM) maintains(More)
Time has played only a limited role within the traditional theories of Pavlovian conditioning. Although temporal factors certainly contribute to whether conditioning occurs, the traditional assumption in the associative framework has been that associations lack temporal information. Recently, the temporal coding hypothesis has challenged that view, arguing(More)
Kamin (1968) reported reduced conditioned responding to a cue (X) that was paired with an unconditioned stimulus (US) in the presence of a second cue (A) as a result of A's having been previously paired with the US. This phenomenon, called " blocking, " has been traditionally interpreted as an acquisition failure, in which the prior training with A prevents(More)
For many years, students of learning have been interested in the circumstances under which the inhibitory properties of a stimulus will transfer to other stimuli. Conditioned inhibitors may be established through several procedures, the most common of which is the procedure of Pavlov (1927). In Pavlov's procedure, a conditioned stimulus (CS) is(More)
Seven undergraduates participated in a concurrent-choice experiment with monetary reinforcers. Response-independent analogues of variable-interval and variable-ratio schedules were used to assess whether subjects would maximize reinforcement rate. The optimal pattern of behavior, in terms of maximizing reinforcement rate, involved a large bias toward the(More)
The Hall-Pearce (1979) negative transfer effect in rats was used to examine whether temporal relationships are coded as part of the informational content of associations that results from CS-US pairings. The transfer effect consists of a deficit in conditioned responding following CS-USstrong pairings in Phase 2 that results from prior CS-USweak pairings in(More)
Three experiments with rats used conditioned suppression of barpress to test predictions of the extended comparator hypothesis, which assumes that the effectiveness of (first-order) comparator stimuli in modulating responding to a target conditioned stimulus (CS) is itself modulated by other (second-order) comparator stimuli. Experiment 1 demonstrated that(More)
The overexpectation effect in Pavlovian conditioning is produced by pairing a compound of two conditioned stimuli (CSs) A and X with an unconditioned stimulus (US) following independent pairings of each CS alone with the US. The typical result is reduced responding to the target CS (X) following compound conditioning, relative to a control group that did(More)