Simultaneous Visual Discrimination Research Articles

Stimulus information and primate discrimination learning: The influence of postresponse stimulus information

This paper describes an experiment concerned with the operation of discriminatory processes subsequent to an individual's overt choice response and how these may be affected by extrinsic stimulus information. The experiment used subhuman primates and was conducted within the simultaneous two-choice visual discrimination paradigm. The major results of the experiment indicated that: (1) learning performance may be significantly interfered with by irrelevant postresponse stimulus information, and (2) this interference is primarily associated with the presentation of irrelevant information subsequent to nonreinforced choice responses. The results are discussed in terms of the relation between the occurrence of reinforcement and the operation of memory storage processes.

Behavioral and biochemical effects of alpha-methyltyrosine in cats.

A single dose of orally administered DL-α-methyltyrosine methylester hydrochloride (AMT) significantly increased the number of errors made by cats performing a spatial delayed response (DR) task. The same doses of AMT had no such effect on simultaneous visual discrimination (VD) performance. Response latencies were increased in all cats, whichever task performed. In an attempt to correlate the behavioral and biochemical effects of AMT, dopamine (DA), noradrenaline (NA) and serotonin (5-HT) were assayed in 5 brain structures, 4 to 48 h after 100 to 175 mg/kg. DA was reduced significantly with all doses of AMT used, NA with doses of 125 mg/kg and more. 5-HT increased significantly after 100 and 125 mg/kg but remained unchanged after higher doses. Due to the simultaneous action of AMT on DA, NA and 5-HT, the respective roles of these amines are difficult to dissociate. In contradistinction, previous findings suggest that brain DA be responsible for the impairment of DR performance.

The effects of electrical (blocking) stimulation to the dorsal hippocampus of the rat on learning of a simultaneous brightness discrimination

Twenty-four rats were chronically implanted with bilateral bipolar electrodes in the CA1 region of the dorsal hippocampus. Animals were then trained on a simultaneous visual discrimination task under several conditions of stimulation. Compared with 8 operated and 8 unoperated controls, 8 rats receiving 1 2 sec train of pulses every 3·0 sec given continuously throughout the learning period showed severe disruption of learning. A further 8 rats given 2·0 sec of stimulation 5·0 sec after each response also showed disruption of learning but some learning took place. After criterion performance was achieved “continuous” stimulation resulted in a significant increase in errors but “2 sec” stimulation led to no significant change in the number of correct responses. Stimulation during learning resulted in a strong persevarative response tendency. These results were considered in terms of a registration-consolidation-retrieval continuum.

Stimulus function in errorless simultaneous discrimination.

Pigeons trained to perform a simultaneous visual discrimination with few or no errors by a procedure in which the negative stimulus (S—) was gradually introduced, preferred a neutral (novel) stimulus (S°) to the S—used in the original training. Ss receiving more abrupt presentation of S— and who made more errors, chose randomly between S— and S°. These data suggest that S— may be inhibitory or aversive following errorless learning.

The effects of irrelevant dimensions and stimuli on two-choice discrimination learning by children

Eight 9-year-old children were presented 24 eight-trial simultaneous two-choice visual discrimination problems. Each problem contained eight different stimuli. In half of the problems the stimuli varied along two dimensions with one dimension irrelevant, and for the other 12 problems the stimuli varied along three dimensions with two dimensions irrelevant. Even though the number of irrelevant stimuli was the same, the two-irrelevant-dimension problems were significantly more difficult than the one-irrelevant-dimension problems. There was significant learning on both types of problems and no significant interactions.

Effects of Correction and Non-Correction Training Procedures on ‘Easy’ and ‘Hard’ Discrimination Learning in Children

The effects of correction and non-correction training procedures on 4- and 5-yr -old children's two-choice simultaneous visual discrimination learning were examined when either ‘easy’ or ‘hard’ tasks were presented. Forty children served as Ss. The results indicated that performance on the more difficult problem was facilitated by the use of a correction procedure. On the other hand, there was very little difference between the group trained with the correction procedure and that trained with the non-correction procedure on the ‘easy’ task.

Two-choice discrimination learning using multiple stimuli

In two experiments rats were trained in a Y maze on a two-choice simultaneous visual discrimination in which either a constant positive stimulus was used and the negative stimulus varied from trial to trial, or a constant negative stimulus was used and the positive stimulus varied. In both experiments the constant S-multiple S+ discrimination was easier to learn than the constant S+ multiple S-discrimination.

Dimensional shifts and cue retention in retardate discrimination learning

The theoretical systems of Zeaman, House, and Goodwin and Lawrence were used to predict performance in intradimensional (ID) and extradimensional (ED) shifts and in conditions designed to test the retention of previously acquired cues. Sixty retarded children were divided into six groups and given the same original training on a simultaneous visual discrimination problem. Groups were given either two successive ID or ED shifts after original training. Within each second shift, three types of cue conditions were present: (a) The same condition which had the identical cues and reinforcement contingencies of original training, (b) the New condition in which cues, not experienced previously, were used, and (c) the Reversal condition in which the cues of original training were present but reinforcement contingencies reversed. The findings were: (a) ID-shift performance was superior to ED-shift performance in the second shifts and (b) performance in the Same condition was superior to performance in the New and Reversal conditions. Implications of these findings for the Zeaman and House and Goodwin and Lawrence positions are discussed.

Reversal learning Improvement in the fish Astronotus ocellatus (Oscar)

Two Oscars were given over 140 sessions of a simultaneous visual discrimination. Contrary to most reversal studies with fish, between-reversals improvement occurred for both Ss. Species and methodological differences may account for this difference in results.

Intradimensional and extradimensional shift learning by pigeons

Pigeons were trained consecutively on two simultaneous visual discriminations. For half the Ss, the dimension relevant in the first problem remained relevant in the second (intradimensional shift); for the remainder, the dimension irrelevant in the first problem became relevant in the second (extradimensional shift). As is predicted by two-stage theories of discrimination learning, the intradimensional shift was learned more rapidly than the extradimensional shift.

The effects of chlorpromazine and secobarbital on matching from sample and discrimination tasks in monkeys.

Monkeys were trained in the performance of a matching from sample task and in two simultaneous visual discrimination tasks differing in level of difficulty. In the case of the matching task, four doses each of chlorpromazine and of secobarbital were administered to the animals according to a balanced design. The procedure was then replicated. The results of the matching task indicated that chlorpromazine produced many errors of omission and few errors of commission. The latter kind of error as well as other measures of confused responding were seen primarily with secobarbital. In the case of the visual discriminations, secobarbital produced greater impairment of the more difficult (pattern) task than of the simpler (color) task; chlorpromazine had equivalent effects on the two tasks. The similarity between the secobarbital action and the behavioral consequences of certain cortical lesions in the monkey was discussed.

Facilitation of simultaneous visual discrimination by nicotine in four "inbred" strains of mice.

Five-choice visual discrimination learning was determined in four different strains of inbred mice. All strains were able to learn this task in a small number of sessions. By distributing or massing the practice further evidence was obtained suggesting that efficient consolidation mechanisms characterize the strain DBA/2J while short-term memory characterizes C3H/He mice.

Progressive acquisition of relevant cues in visual pattern discrimination by monkeys.

Three monkeys, on a self-shaping regimen, learned a 6+ vs 4– simultaneous visual pattern discrimination. The stimuli were projected randomly upon translucent panels at 2 of 16 possible locations for each trial. In tabulating all panel presses during acquisition, it is shown that decreased preference for non-illuminated (blank) panels is attended by an increased preference for both the positive and the negative stimuli. Criterion-level preference exclusively for the positive stimulus thus does not occur until a markedly increased preference for the negative stimulus is eliminated.

The effect of redundant patterns on retardate discrimination learning

Eight retarded children ran in a two-choice simultaneous visual discrimination task under four stimulus conditions. Condition 1 used two common objects as stimuli, Condition 2 used two pictures of common objects as stimuli, Condition 3 used two stimulus cards each containing two different pictures and Condition 4 used two stimulus cards each containing two identical pictures. Condition 4 was easiest and Condition 3 hardest for the Ss. Conditions 1 and 2 were intermediate and approximately equal in difficulty.

A developmental study of attention to cue redundancy introduced following discrimination learning

Following original learning (OL) of a two-choice simultaneous visual discrimination problem by second and sixth grade Ss, the cues of the elevant and irrelevant dimensions were made 100% redundant during a 40 trial overtraining (OT) period. A control group received 40 OT trials without the redundancy. The effects of the redundancy pairing were assessed by a subsequent learning problem in which the only relevant cues were those which had been irrelevant in OL. For half the experimental Ss the OL-irrelevant cue which had been paired with the OL-positive cue during overtraining was made positive, while for the other half the cue paired with the negative OL stimulus was made positive. The data indicated that the redundancy period resulted in both instrumental response strength to the OL irrelevant cues, and a response to the dimension represented by them. Relative transfor effects for the two grade levels supported the interpretation that during the redundancy phase the younger children attended to the previously irrelevant stimuli more, i.e., “focused” on OL relevant stimuli less, than was the case with the older children. In a second study identical procedures were followed except that the correct and incorrect stimuli were identified for the S before the OL period began. The results for second grade Ss suggested that there might be decreased dimensional responding to the previously irrelevant cues during OT under these OL-instructed conditions.

Proactive inhibition in rats after prior partial reversal: A critique of the spontaneous recovery hypothesis

Forty-eight rats were taught a simultaneous visual discrimination, S1+ vs S2−. Subsequently, they learned a second discrimination, involving one of the old stimuli and a new one. Half of them now learned S3+ vs S1−. The other half learned S2+ vs S3−. Retention of the second discrimination was tested one day or 32 days after training. The two different partial reversals resulted in proactive inhibition and to the same degree. It is argued that this result is inconsistent with the spontaneous recovery interpretation of proactive inhibition.

Habit reversal in the crow, corvus Americanus

Two crows were run on multiple reversals of a simultaneous visual discrimination problem. The crows showed a marked progressive decrease in errors to criterion over the series of reversals. Their performance appeared to be superior to that of more primitive but more widely studied avians such as the pigeon. The crows’ performance also differed from that found in the rat in that the latter’s performance in reversal situations has generally been characterized by an initial increase in errors per reversal followed by a progressive decrease.

Facilitation of simultaneous visual discrimination by nicotine in the rat.

Effects of nicotine are tried with an increasing difficult visual discrimination learning in the rat. The animals could avoid the electrical shock by choosing the right pattern of the only movable door adjacent to the goal box. Different couples of patterns were used.

Stimulus correlates of visual pattern discrimination by monkeys: pattern complexity.

14 rhesus monkeys were presented 2-choice simultaneous visual pattern discrimination problems which were designed to provide estimates of the extent to which 3 physical dimensions of metric patterns determine discriminability. The results replicated our previous reports that discriminative performance was directly related to Element Disparity (ED) and Contour Disparity (CD), and that the ED and CD effects were independent. Performance was inversely related to a trichotomous dimension of Pattern Complexity (PC), but a more detailed analysis revealed that the effect of PC could be attributed solely to the effect of the Sides Level (SL) dimension identified previously.

A Note on Further Experiments on the Effects of Meprobamate on Discrimination Performance in the Monkey

Abstract A previous experiment (Gross and Weiskrantz, 1961) has shown that performance on a successive auditory discrimination task is impaired by injections of meprobamate. The present two brief experiments indicate that the drug also impairs simultaneous visual discrimination performance, although not to the same degree as found earlier for auditory discrimination. The original finding, therefore, cannot be attributed simply to unique features of the auditory discrimination situation, such as the “go—no-go” response contingency. Since neither overtraining nor drug habituation appears to be of great importance, it is suggested that the lesser effect of the drug in these experiments reflects the greater stability of visual than auditory habits in the monkey. Earlier work has shown that meprobamate and reserpine can cause a severe deterioration in auditory discrimination performance of monkeys (Gross and Weiskrantz, 1961). This result was taken as supporting a hypothesis, growing out of still earlier resea...