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Results for “Probability Learning”

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At least 109 records · Page 6Linked to original sources
PubMed1989

Discrimination of duration ratios.

Trained pigeons to make discriminations on the basis of the ratio of two stimulus durations. A red light of one duration was followed by a green light of a different duration, with 900 red-green pairs intermixed over trials. A choice followed the red-green pair; a response to a green side key was reinforced if the red-green ratio was less than a criterion ratio, and a response to a red side key was reinforced if the ratio exceeded the criterion. Reinforcement depended on whether red or green was longer under the basic condition; in other conditions, however, reinforcement depended on whether one duration was two or four times longer than the other. Sensitivity was similar across conditions, for the basic shorter-longer rule, and for the more complex rule of one duration as two or four times the other. Most choices were made on the basis of the ratio relation between the two durations and according to Weber's law. These results extend the findings of Dreyfus, Fetterman, Smith, and Stubbs (1988), and provide a new methodology for psychophysical scaling with animals.

Animals↗
PubMed1987

Implicit learning in patients with probable Alzheimer's disease.

The purpose of the present study was to determine whether patients with probable Alzheimer's disease (AD) were capable of implicit procedural learning. AD patients and elderly control subjects were given a serial visual reaction time task with an embedded repeating sequence. The AD patients responded more slowly than the controls, but many nonetheless showed learning of the repeating sequence. Patients who failed to learn the sequence were similar in age and overall severity of dementia to those who learned, but they scored lower on some tasks of nonverbal reasoning.

Aged↗
PubMed1990

The method of constant stimuli is inefficient.

Simpson (1988) has argued that the method of constant stimuli is as efficient as adaptive methods of threshold estimation, and has supported this claim with simulations. We show that Simpson's simulations are not a reasonable model of the experimental process, and that more plausible simulations confirm that adaptive methods are much more efficient than the method of constant stimuli.

Attention↗
PubMed1990

The role of contingency in classical conditioning.

The assumption that classical conditioning depends on a contingent relation between the conditioned stimulus (CS) and the unconditioned stimulus (US), which was proposed some decades ago as an alternative to the traditional contiguity assumption, still is widely accepted as an empirical generalization, if no longer as a theoretical postulate. The first support for the contingency assumption was provided by experiments in which occasional CS-US pairings produced no response to the CS in random training--i.e., training in which the probability of the US was the same in the presence and absence of the CS. Those early experiments, the results of which too often are taken at face value, are reconsidered along with various later experiments that show conditioning, both of the CS and its context, in random training. The evidence suggests that CS-US contingency is neither necessary nor sufficient for conditioning and that the concept has long outlived any usefulness it may once have had in the analysis of conditioning.

Animals↗