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PubMed1975

Effects of verbal rehearsal on discrimination learning in moderately retarded and nursery-school children.

In a simultaneous discrimination task with intradimensional shift, low-IQ and average-IQ children were required either to rehearse audibly a phase relating the positive cue to reward or not to rehearse audibly. A limited number of rehearsal trials substantially reduced discrimination errors and the facilitating effect transferred fully when new color cues were introduced and audible rehearsal stopped. Retarded subjects tended to need extra prompting to rehearse, but their discrimination performance showed no reliable deficit. It seems valuable to view the equal-MA deficit that retarded subjects have previously displayed on discrimination tasks as a consequence of deficiency in short-term memory strategies.

Child, Preschool↗
PubMed1962

Generalization gradients of inhibition following auditory discrimination learning.

A more direct method than the usual ones for obtaining inhibitory gradients requires that the dimension of the nonreinforced stimulus selected for testing be orthogonal to the dimensions of the reinforced stimulus. In that case, the test points along the inhibitory gradient are equally distant from the reinforced stimulus. An attempt was made to realize this condition by obtaining inhibitory gradients along the frequency dimension of a pure tone after discrimination training in which the nonreinforced stimulus was a pure tone (or tones), and the reinforced stimulus was either white noise or the absence of a tone. The results showed that some degree of specific inhibitory control was exerted by the frequency of the tone, although the gradients were broad and shallow in slope.A further experiment was conducted to see whether the modification of an excitatory gradient resulting from training to discriminate neighboring tones could arise from a simple interaction of inhibitory and excitatory gradients. The results indicated that it could not, since discrimination training produced a concentration of responding in the vicinity of the reinforced stimulus which cannot be derived from any plausible gradient of inhibition.

Discrimination Learning↗
PubMedDate not supplied

Different parameters support generalization and discrimination learning in Drosophila at the flight simulator.

We have used a genetically tractable model system, the fruit fly Drosophila melanogaster to study the interdependence between sensory processing and associative processing on learning performance. We investigated the influence of variations in the physical and predictive properties of color stimuli in several different operant-conditioning procedures on the subsequent learning performance. These procedures included context and stimulus generalization as well as color, compound, and conditional discrimination (colors and patterns). A surprisingly complex dependence of the learning performance on the colors' physical and predictive properties emerged, which was clarified by taking into account the fly-subjective perception of the color stimuli. Based on estimates of the stimuli's color and brightness values, we propose that the different tasks are supported by different parameters of the color stimuli; generalization occurs only if the chromaticity is sufficiently similar, whereas discrimination learning relies on brightness differences.

Animals↗
PubMed1977

Sequential contrast effects with retarded subjects after discrimination learning with and without errors.

Four retarded adults were exposed to a multiple variable interval-extinction schedule of reinforcement. The 2 min components were presented in a random order. Two subjects acquired the discrimination with an errorless procedure. The two other subjects learned the discrimination with errors. The schedule generated sequential contrast effects under both training procedures: response rates during periods of reinforcement were higher when a reinforcement period followed an extinction period than when it followed another reinforcement period. These results were confirmed in a second observation where eight retarded children were exposed to a multiple fixed ratio-extinction schedule of reinforcement. This study is the first demonstration of sequential contrast effects with human subjects during the acquisition of a discrimination without errors. The results are discussed in terms of Terrace's theory of errorless learning.

Adolescent↗
PubMed2003

Perinatal exposure to diethylstilbestrol improves olfactory discrimination learning in male and female Swiss-Webster mice.

During late prenatal and early postnatal brain development, estrogen induces structural sex differences that correspond to behavioral differences in certain domains such as learning and memory. The typically superior performance of males is attributed to the action of elevated concentrations of estrogen, derived inside neurons from the aromatization of testosterone. In contrast, female performance appears dependent on minimal estrogenic activity. Rat models of the relationship between hormones and cognitive behavior predominate the field, but the advent of genetically modified mice as research tools necessitates development of analogous mouse models. This study examined how early postnatal exposure to the synthetic estrogen diethylstilbestrol (DES) affected the ability of male and female Swiss-Webster mice to learn a two-choice olfactory discrimination and three repeated reversals. Mice treated with subcutaneous injections of DES from postnatal days 1-10 learned reversals more readily than oil-treated controls, a difference that became evident after repeated testing. DES-exposed males and females learned reversals at a comparable rate, suggesting that early postnatal estrogen exposure does not influence this mode of learning through a sexually differentiated mechanism in mice. An analysis of response patterns during qualitatively different phases of reversal learning revealed that DES-induced improvements probably were not due to greater inhibitory control. Instead, DES appeared to enhance associative ability. Early postnatal estrogen exposure may have the potential to preserve certain cognitive skills in adulthood.

Animals↗
PubMed1969

Extinction of a discriminative operant following discrimination learning with and without errors.

Different groups of pigeons were trained to respond to red and not to green with and without errors (responses to green) under a free operant procedure, in which responding to red was intermittently reinforced, and under a trial procedure in which all responses to red were reinforced. The response to red was then extinguished under a procedure in which the discriminative stimuli were successively alternated as during discrimination training. The performances of those birds that learned the discrimination without errors under the trial procedure were seriously disrupted during extinction; the birds persistently responded to green for the first time. The performances of those subjects that learned the discrimination without errors under the free operant procedure were not disrupted during extinction. In a second experiment, the same discrimination was trained without errors under a trial procedure in which the response to red was intermittently reinforced. Extinction did not disrupt discrimination performance. Thus, errorless discrimination performance was shown to remain intact during extinction so long as the response to red was intermittently reinforced during discrimination training.

Journal Article↗