PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Probability Learning”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1975

Probability learning in retarded children with differing histories of success and failure in shcool.

The effects of school-induced success and failure experiences on the probability-learning performances of retarded children were investigated. In previous laboratory research, the hypotheses has been suggested that failure experiences would lead to greater maximization, less patterning, and less shifting of responses than success experiences. Fifteen retarded children exposed to repeated failure in the classroom, 15 retarded children exposed to a relatively high level of success in special-education classes, and 15 nonretarded children served as subjects. All subjects were matched for MA. The hypothesis suggesting that the laboratory findings generalized to the classroom was confirmed. In addition, it was found that locus of control and need for achievement were significant correlates of probability-learning performance. However, only locus of control differentiated the subject groups.

Achievement↗
PubMed1978

Effects of low concentrations of enflurane on probability learning.

The effects of controlled subanaesthetic concentrations of enflurane on learning behaviour and on ability to change previously developed decision strategies were studied in 10 male volunteers, using a probability learning task. Subjects were instructed to predict on each of 200 consecutive trials, whether a left or a right light would appear. The appearance of lights was pre-determined by a set relative frequency unknown to the subject. The relative frequency was automatically changed at the end of the first 100 trials, from 8/10 lights in the left side to 4/10. It was found that enflurane at subanaesthetic concentration of 0.25% (end-tidal) slowed the rate of learning, and increased the number of trials required for readjusting the prediction strategy to the changed situation.

Adult↗
PubMed1976

Spatial probability learning by alcoholic Korsakoff patients.

Performance of 10 alcoholic Korsakoff patients was compared to that of 10 normal and 10 alcoholic control subjects on each of three different schedules of spatial probability learning (50:50, 70:30, and 30:70) using monetary reinforcement and a correction procedure. There was some evidence that the Korsakoff patients were less sensitive than normals to the effects of reward: Although on all three schedules, choice ratios by normal subjects approximated the reinforcement ratios, the choice ratios of Korsakoffs on the second and third schedules remained close to the reinforcement ratio acquired with the first schedule. In addition, the Korsakoffs made an abnormal number of perseverative errors early in training. On most measures, performance by alcoholic controls fell between that of the other two groups.

Adult↗
PubMed1976

Spatial probability learning by alcoholic Korsakoff patients.

Performance of 10 alcoholic Korsakoff patients was compared to that of 10 normal and 10 alcoholic control subjects on each of three different schedules of spatial probability learning (50:50, 70:30, and 30:70) using monetary reinforcement and a correction procedure. There was some evidence that the Korsakoff patients were less sensitive than normals to the effects of reward: Although on all three schedules, choice ratios by normal subjects approximated the reinforcement ratios, the choice ratios of Korsakoffs on the second and third schedules remained close to the reinforcement ratio acquired with the first schedule. In addition, the Korsakoffs made an abnormal number of perseverative errors early in training. On most measures, performance by alcoholic controls fell between that of the other two groups.

Adult↗
PubMed1976

[The role of uncertainty in the conditioned-reflex learning behavior for selected cardiovascular functions].

As a contribution to quantitative analysis of exogenous stress action, the role of probability learning (probability stress, probability affirmation) for selected cardio-vascular functions was studied in 25 albino rats and 8 dogs. It has been shown in the rats learning with probability stress that a dependence exists between stress probability, on the one hand, and conditional-reflectory processes and systolic blood pressure rise, on the other, that is, the pathogenic action of probability stress increases from a probability of p = 1.0 to p = 0.5. An analogous picture was found with the probability affirmation being applied in dogs. While a probability affirmation with p = 1.0 promoted adaptational processes, a value of p = 0.5 led to experimental neurosis, tachycardia and ECG alterations. The results obtained are discussed in context with the information entropy and information theory of emotions.

Animals↗
PubMed1991

Choice as a function of local versus molar reinforcement contingencies.

Rats were trained on a discrete-trial probability learning task. In Experiment 1, the molar reinforcement probabilities for the two response alternatives were equal, and the local contingencies of reinforcement differentially reinforced a win-stay, lose-shift response pattern. The win-stay portion was learned substantially more easily and appeared from the outset of training, suggesting that its occurrence did not depend upon discrimination of the local contingencies but rather only upon simple strengthening effects of individual reinforcements. Control by both types of local contingencies decreased with increases in the intertrial interval, although some control remained with intertrial intervals as long as 30 s. In Experiment 2, the local contingencies always favored win-shift and lose-shift response patterns but were asymmetrical for the two responses, causing the molar reinforcement rates for the two responses to differ. Some learning of the alternation pattern occurred with short intertrial intervals, although win-stay behavior occurred for some subjects. The local reinforcement contingencies were discriminated poorly with longer intertrial intervals. In the absence of control by the local contingencies, choice proportion was determined by the molar contingencies, as indicated by high exponent values for the generalized matching law with long intertrial intervals, and lower values with short intertrial intervals. The results show that when molar contingencies of reinforcement and local contingencies are in opposition, both may have independent roles. Control by molar contingencies cannot generally be explained by local contingencies.

Animals↗
PubMed1975

Effects of nitrous oxide on decision-strategy and sustained attention.

Effects of 10,20, and 30% N2O on decision-making strategy, reaction-times, sustained attention, the Digit Symbol Subsititution Test (DSST), short-term memory and the Clyde Mood Scale were assessed in 12 test subjects. Decision-making strategy, as measured by 2-choice probability-learning, was unaffected by 30% N2O once a strategy had been formulated, but reaction-times were increased. Sustained attention was significantly affected in 33% of our subjects, whereas performance on the DSST and on the short-term memory task was impaired in virtually all subjects. Changes were noted in several mood-scale factors with 30% N2O. No residual drug effects were found.

Adolescent↗
PubMed1977

Schizophrenic subtypes and differential responsiveness to reward and punishment.

Variations in responsivity to primary, secondary asocial and interpersonal rewards and punishments between major schizophrenic subgroups were investigated in a probability learning study. The subgroups compared were process and reactive, paranoid and nonparanoid, long- and short-hospitalization, and long- and short-length of illness schizophrenics. No evidence of differential responsivity to these reward-punishment/modality combinations appeared between high and low scorers on any of the four schizophrenic subgrouping dimensions. The groups then were matched closely so that the effects of each individual difference measure could be evaluated independently of the other three. Again, no significant differences in responsiveness to the reinforcement/modality combinations appeared. The results do not support the view that any of the four dimensions relate to differential responsiveness to primary, secondary asocial or verbal reward or punishment--at least on relatively simple tasks.

Adult↗
PubMed1975

Toxicity of marijuana and tobacco smoking in the beagle.

Four cigarettes of marijuana or tobacco in the form of smoke inhaled into the trachea were administered to dogs daily over a period of nine months. Marijuana caused a slowing of body weight gain. Food consumption increased at first and was accompanied by diarrhea; then it decreased. This suggests a malabsorption of food or a more fundamental metabolic disturbance. The tobacco smoking group consumed much less food without showing any significant change in body weight gain in 3 and 6 months, but it did in 9 months only. In marijuana smoking dog, blood pressure remained unchanged. The resting heart rate was increased (by 32% at 3, 30% at 6, and 15% at 9 months). Alpha1-globulin, eosinophils and lymphocyte count were significantly decreased. A decrease in serum triglycerides was noted. In addition, a behavioral study permitted us to note a general perturbation in the behaviour of the marijuana smoking dogs. The dogs showed impairment of learning, probably due to these behavioral perturbations.

Animals↗
PubMed1992

Learning mechanisms in matching to sample.

A model system and an experiment on early learning and decision processes in matching-to-sample and oddity-from-sample tasks are presented. The model system is based, in part, on videotaped records of pigeons' looking responses before they chose 1 of 2 comparison stimuli. In order to see the wavelength stimuli recessed behind the pecking keys, the pigeons had to move in front of them. Although there were slight increases in the acceptance probability with switches between the stimuli before a choice response, the overall decision strategy was close to a Markov choice process in which choice proportions could be predicted by the product of each rejection probability and the final acceptance probability. Learning involved learning to discriminate rather than learning to adopt a stricter criterion for an acceptable sample match.

Animals↗
PubMed1992

The relation of children's single word utterances to single word utterances in the input.

The reported study investigated the relation between children's single-word utterances and maternal single-word utterances expressing similar communicative intents. Twenty-four Hebrew-speaking dyads (the children about 1;6) were videotaped for 30 min in an unstructured session. Single-word utterances were analysed for their communicative intent and the relationship of the expression to the underlying intent was defined in the form of realization rules. Of 17,471 child utterances, 97.0% were realizations that were also used by mothers for expressing the same communicative intent. The most frequently modelled rule for an intent had the highest chance of being adopted by children, and the probability sharply decreased for the relatively less frequently modelled rules. The results suggest that children's single-word utterances are similar to, and probably learned from, single-word utterances of caretakers expressing the same specific communicative intents.

Child Language↗
PubMed1992

A table of d' for M-alternative odd-man-out forced-choice procedures.

There is a class of multiple-alternative forced-choice psychophysical procedures in which the subject is required to identify which one of a number of stimuli differs from the remaining stimuli, without having to consider the direction or sign of the difference. A table giving values of the discrimination index d' as a function of the proportion of correct responses in such odd-man-out procedures was generated by numerical simulation. The table covers experiments with 3 to 32 alternative stimuli.

Attention↗
PubMed1992

Dissociation of theories of choice by temporal spacing of choice opportunities.

Rats were trained on a discrete-trial version of a concurrent variable-interval (VI) variable-ratio (VR) schedule in which the relative reinforcement rates were varied across conditions. Subjects with the shorter intertrial interval (ITI) had a significant bias toward the VR alternative, as predicted by optimality theory, and were also more likely to choose the VI alternative with longer times since responses to the VI alternative, as predicted by momentary-maximizing theory. Subjects with the longer ITI failed to show either of these effects. Approximation to the matching law was greater with the longer ITI. Thus, matching is not derivative of the processes postulated by optimality or momentary-maximizing theory but instead is in competition with those processes.

Animals↗
PubMed1978

Deficits in visual learning produced by posterior temporal lesions in cats.

Eight cats with lesions in the posterior temporal (PT) cortex, seven cats with lesions in the basolateral amygdala (BLA), and eight intact controls were observed on eight tests of visual discrimination learning and of spontaneous responses to salient visual stimuli. The effects of the two lesions were somewhat dissociable. The PT lesions were accompanied by a severe deficit in pattern discrimination learning but no loss in visual tracking or orientation to the silhouette of a threatening cat. The BLA lesions produced a milder and less consistent loss in pattern discrimination but serious defects in tracking and reponse to the cat silhouette. Both operated groups performed well on the visual cliff. The deficit from PT lesions appeared independent of damage to the geniculocortical system. The parallel of symptoms from PT lesions in cats and inferotemporal lesions in monkeys is discussed.

Amygdala↗
PubMed1992

Loss of the Kamin blocking effect in acute but not chronic schizophrenics.

Differences between research diagnostic criteria (RDC)-diagnosed acute and chronic schizophrenics and normal controls were studied using a Kamin blocking procedure. Blocking is an established animal learning procedure, thought by some researchers to reflect selective attention; decreased blocking indicates increased processing of irrelevant stimuli. It was predicted that this pattern would be obtained in acute schizophrenics, tested soon after admission, for two reasons: (1) evidence from previous clinical studies indicates that acute schizophrenics are more aware of nonsalient aspects of their environment than controls; and (2) blocking is disrupted in animals in a hyperdopaminergic state and restored by neuroleptic medication. This was the case: acute, but not chronic, schizophrenics showed disrupted blocking. This disruption was especially clear in those acute schizophrenics tested within 2 weeks of hospital admission. By the second test session (in a cross-over design), there was some evidence of normalization in performance in the acute schizophrenics. These findings are considered with regard to the dopamine hypothesis of schizophrenia.

Acute Disease↗