The aim of this study was to model a situation that induced choice between following two incompatible rules, each associated with a different rate of reinforcement. In Experiment 1, eight undergraduate students were exposed to a two-component multiple schedule (training). In each component, there was a concurrent variable interval (VI)-extinction…

Learning to categorize perceptually similar stimuli can result in people becoming more sensitive to differences along perceptual dimensions that are relevant to category membership and/or less sensitive to equivalent differences along irrelevant perceptual dimensions. These effects of acquired distinctiveness and acquired equivalence may be caused…

Two experiments tested whether a peak-shifted generalization gradient could be explained by the averaging of distinct gradients displayed in subgroups reporting different generalization rules. Across experiments using a causal judgment task (Experiment 1) and a fear conditioning paradigm (Experiment 2), we found a close concordance between…

For over a century and a quarter, the science of learning has expanded at an increasing rate and has achieved the status of a mature science. It has developed powerful methodologies and applications. The rise of this science has been so swift that other learning texts often overlook the fact that, like other mature sciences, the science of…

Vibrotactile intensity-discrimination thresholds for sinusoidal stimuli applied to the thenar eminence of the hand declined as a function of practice. However, improvement was confined to the tactile information-processing channel in which learning had occurred. Specifically, improvements in performance with training within the Pacinian-corpuscle…

Extinction is generally more fragile than conditioning, as illustrated by the contextual renewal effect. The traditional extinction procedure entails isolated presentations of the conditioned stimulus. Extinction may be boosted by adding isolated presentations of the unconditioned stimulus, as this should augment breaking the contingency between…

In both healthy participants and various patient populations, performance on attentional set-shifting tasks has been found to be affected by learned irrelevance and/or perseveration. The present study examined whether or not these processes also play a role during the initial discrimination learning phase of those tasks. To this end, participants…

Individuals with anxiety disorders often do not respond to safety signals and hence continue to be afraid and anxious. Consequently, it is important to develop paradigms in animals that can directly study brain systems involved in learning about, and responding to, safety signals. We previously developed a discrimination procedure in rats of the…

Results of a study with 10 moderately retarded adolescents on the salience of transverse compound stimuli (combinations of positive and negative cues) were interpreted as an instance of developmental changes in unlearned stimulus salience hierarchies. The low saliency of transverse compounds was suggested to be related to reading difficulties.…

Studied developmental changes in optional shift discriminations using kindergartners, second graders, sixth graders, and college students. (DR)

Learning to discriminate between spatial locations defined by two adjacent arms of a radial maze in the conditioned cue preference paradigm requires two kinds of information: latent spatial learning when the rats explore the maze with no food available, and learning about food availability in two spatial locations when the rats are then confined…

Research supported by a U.S. Public Health Service fellowship grant and by grant No. 01368-04 from the National Institute of Child Health and Human Development.

The purpose of the two experiments was to assess the effects of two levels of stimulus redundancy and three levels of irrelevant visual stimulation on performance in a successive discrimination task and a reproduction task. The results indicate that increases in redundancy facilitated performance in the reproduction task but had no appreciable…

Results of numerous human imaging studies and nonhuman neurophysiological studies on "reward" highlight a role for frontal, striatal, and thalamic regions in operant learning. By integrating operant and functional neuroimaging methodologies, the present investigation examined brain activation to two types of discriminative stimuli correlated with…