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PubMed1988

Stimulus equalization: temporary reduction of stimulus complexity to facilitate discrimination learning.

Learners with limited behavioral repertoires often have difficulty discriminating complex, multidimensional stimuli. Procedures that use gradual stimulus change have been developed to facilitate such discrimination, but these procedures are often difficult to implement and costly in terms of teacher time and expertise. This study investigated the effectiveness of stimulus equalization, an error reduction procedure involving an abrupt but temporary reduction of dimensional complexity. A microcomputer was used for stimulus presentation, data collection, and response analyses. Preschool children's responding to groups of four stimuli differing along several dimensions was analyzed on four discrimination tasks under several conditions. On each task, one element from a different dimension was programmed as correct. When trial-and-error training failed to establish the discrimination, equalization training began in which differences in the irrelevant dimensions were eliminated. When correct responding developed, the differences were reinstated, and correct performance was maintained in all but one instance. In a repeated acquisition design, stimulus equalization was found to be generally effective and superior to the trial-and-error method. Implications for computer-assisted instruction are discussed.

Attention↗
PubMed1976

Functional differentiation within the neostriatum of the rat using electrical (blocking) stimulation during discrimination learning.

Sixteen rats, eight with bipolar electrodes implanted bilaterally in the anterodorsal head of the caudate-putamen and eight with similar electrodes in the posteroventral caudate-putamen, learned a spatial and a form discrimination task and their reversals while receiving "continuous" stimulation. Rats receiving stimulation to the anterodorsal caudate-putamen were imparied on spatial reversal learning compared with the posteroventral group. On form discrimination reversal the posteroventral group were impaired compared with the anterodorsal group. This dissociation is related to the particular cortical neostriatal projection system for the region stimulated and demonstrates a behavioral differentiation in rat neostriatum comparable with that observed in the monkey.

Animals↗
PubMed1978

Attentional changes during discrimination learning by retarded children.

Eight moderately retarded children were trained on a simultaneous two-choice discrimination problem and a series of discrimination-shift problems. The procedure required the subjects to perform overt observing responses to produce elements of the discriminative stimuli, making it possible to measure directly changes in attention to different aspects of stimuli during learning. The patterns of change in observing responses were generally in line with descriptions of attentional changes derived from two-process theories of discrimination learning; for example, the frequency of irrelevant observing responses was high during the presolution period during extradimensional shifts but was low during intradimensional shifts. Contrary to current theories, extradimensional shifts caused an immediate increase in irrelevant observing responses, and intradimensional shifts usually caused an increase in relevant observing responses. Subjects responded to later shift problems by initially increasing both relevant and irrelevant observing responses, then withholding irrelevant observing responses.

Adolescent↗
PubMed1992

Monkeys (Macaca fascicularis) with rhinal cortex ablations succeed in object discrimination learning despite 24-hr intertrial intervals and fail at matching to sample despite double sample presentations.

Six cynomolgus monkeys (Macaca fascicularis) learned preoperatively a set of 10 concurrent object discriminations with 24-hr intertrial intervals. Three then had the rhinal cortex removed bilaterally, whereas the other 3 remained as unoperated controls. The animals with ablations were impaired in reacquiring the preoperatively acquired set but subsequently learned without any impairment a new set of 10 discriminations that was presented in the same way. The monkeys with rhinal cortex ablations then failed to learn delayed matching to sample, with double sample presentations, in 510 trials, whereas the control animals learned this task in 270 trials on average. The results add to existing evidence that rhinal cortex ablation produces a severe impairment in visual short-term recognition memory and show for the first time that this impairment is accompanied by normal long-term discrimination learning ability.

Animals↗
PubMed1989

Unilateral periarcuate and posterior parietal lesions impair conditional position discrimination learning in the monkey.

Monkeys were trained on a conditional position discrimination in which the conditional cue was a light blinking at two distinct rates and the discriminanda (illuminated buttons) appeared in varying symmetrical positions of eccentricity. Unilateral arcuate, posterior parietal, or principal sulcus lesions were performed at criterion. The monkeys were tested to recovery when a homologous lesion was made contralaterally. The first of two analyses examined a period of 4 weeks following each lesion; the unit of analysis was lesions. The arcuate and parietal lesions produced impairments on both widely eccentric and central discriminanda locations; initially, virtually all responses were deflected to the ipsilateral side. There was significant improvement after the arcuate and parietal lesions from weeks 1 to 4. An analysis of total trials to criterion showed major deficits from the second arcuate and parietal lesions, with the arcuate lesion impairment being particularly severe. These results establish that a spatial concept of left vs right is seriously deranged by unilateral lesions of cortical association areas involved in spatial orientation and discrimination.

Animals↗
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↗
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↗
PubMed1991

A computer-controlled Y-maze for the analysis of vibrissotactile discrimination learning in mice.

An automatized, computer-controlled Y-maze is described in which mice are trained to discriminate between two vibrissotactile, and/or visual stimuli, other modalities or combinations of modalities being testable as well. Movements of the mouse are recorded by photocells and monitored on a computer screen. Forward passage of the mouse is ensured by movable gates, and, if necessary, by brief air blows. Wrong choices are punished by air blows as well. The controller is a Hewlett-Packard Series 80 microcomputer with a 16 channel parallel input/output interface; programs are in BASIC. The program analyzes start latency, decision and homing time, side preference, inspections and ultimate choice, as well as choice strategies based on discrimination, left/right habits and short-term memory. Thus we can determine the nature of discrimination errors, and establish individual behavioral profiles of the animals. Results are both printed alphanumerically and plotted. The apparatus may be used for studying sensory physiology as well as cerebral lateralization, and drug or gene effects on memory and learning.

Anesthesia↗