Cue selection in verbal discrimination learning of retarded subjects.

A series of experiments was conducted to examine cue function in trigram verbal discrimination learning by retarded subjects. The issue was to determine the factors that control attention in this type of learning situation. The two variables of chief interest were trigram meaningfulness and reinforcement history. The major general conclusion was that retarded subjects employ complex cue selection strategies in solving a verbal discrimination involving compound verbal stimuli. Major findings were as follows: (a) Retarded subjects exhibit a response bias in favor of words over nonsense trigrams; (b) relatively little active cue selection based on meaningfulness was observed; (c) a compound stimulus discrimination was more difficult to learn than a discrimination involving single verbal stimuli; (d) compound and single stimuli may be processed differently in original discrimination learning; (e) cue position probably controls attention in compound discrimination learning; and (f) a frequency theory of verbal discrimination learning is supported by these data.     

Discrimination and generalization by rats of temporal stimuli lasting for minutes

In three experiments, rats learned to respond differentially to reinforced and nonreinforced trials when the length of the intertrial interval (ITI) predicted the trial outcome (reinforcement or nonreinforcement). Rats in control groups, for whom the length of the ITI did not predict the outcome, did not show differential performance on nonreinforced and reinforced trials. Generalization gradients obtained following discrimination training were comparable to those obtained following discrimination training with other types of discriminative stimuli. That is, groups which had shown differential performance in discrimination training yielded generalization gradients with fastest speeds at the previously reinforced ITIs, slowest speeds at the previously nonreinforced ITIs, and intermediate speeds at ITIs of intermediate length. Control groups yielded flat gradients across all ITIs tested. These effects were shown for relative time discrimination (short time = reinforcement, long time = nonreinforcement, or the reverse) and also for an absolute time discrimination (long and short time = reinforcement, middle time = nonreinforcement or the reverse). This method was effective for time duration measured in minutes rather than seconds, as is more commonly the case.     

Lateralization of temporal lobe dysfunction and verbal encoding

The contribution of encoding deficits to verbal-learning difficulties known to be associated with temporal lobe dysfunction was investigated. Auditory and visual false-recognition tasks, which assess verbal encoding strategies, were given to patients with left-temporal-lobe (LTL) and right-temporal-lobe (RTL) surgical excisions and to a group of normal controls (NC). On both auditory and visual tasks, LTL patients made significantly more false-recognition errors than the other subjects on related, but not unrelated, words in the test list. The findings indicate that LTL patients are able to initially encode verbal material and that a breakdown in information processing occurs at a later stage. On the auditory tasks, the performance of RTL patients did not differ from that of NC subjects. However, on the visual tasks, RTL patients, as compared to both LTL and NC subjects, made fewer false-recognition errors. The performance of RTL patients, in contrast to LTL patients, could be interpreted as a reduced encoding of the visual attribute of verbal material. Another possible explanation considered was difficulty in familiarity discrimination.     

Transfer of the signaling properties of aversive CSs to an instrumental appetitive discrimination

Rats received Pavlovian conditioning in which, based on a shock US, white noise was established for different groups as an aversive CS+, CSo, or CS?. Then, half of each group received the CS contingent upon either the food-reinforced or nonreinforced response in an easy, choice discrimination. Correct responses, i.e., number of reinforcements, to criterion showed that a CS+ for the reinforced response facilitated learning, whereas a CS? retarded learning; conversely, a CS+ for the nonreinforced response retarded learning, whereas a CS? facilitated learning. The same contingency difference occurred with errors to criterion for CS? subjects but was obscured for CS+ subjects apparently by an avoidance-producing effect of the CS+. In support of the generality of the transfer effect, Z-score transforms of the correct-response data showed that the magnitude of transfer was comparable to that obtained in more difficult discriminations. Collectively, the findings indicate that an aversive CS can function as a transformed signal for the presence (CS+) or absence (CS?) of an appetitive reinforcer and that the signal's control of behavior is via a within-chain mediational process.     

Forgetting in retarded and nonretarded persons under conditions of minimal strategy use

Short-term memory processes of mentally retarded (mild, moderate, and severe) and nonretarded persons were compared in a delayed matching-to-sample task that minimized the use of verbal rehearsal. In addition to trials with delays up to 20 s, the inclusion of trials on which the sample and comparison stimuli occurred simultaneously made it possible to isolate memory and discriminability. Forgetting was most pronounced between the simultaneous and 0-s conditions, and nonretarded subjects forgot less than retarded subjects between these conditions. There were no group differences beyond the 0-s delay. Ease of strategy use failed to account for individual differences, and reported strategy use was not related systematically to performance. These findings are incompatible with the hypothesis that normal-retarded differences occur only on tasks involving effortful cognitive strategies. Differences between nonretarded and retarded groups in this study may be due to a failure in automatic encoding processes in retarded persons.     

Auditory temporal perception, phonics, and reading disabilities in children

Reading-impaired and control children were given an experimental battery of nonverbal auditory perceptual tests which examined discrimination and temporal order perception. Stimulus tones were presented at various rates. There were no significant differences between groups on tests in which stimuli were presented at slow rates. However, when the same stimuli were presented more rapidly, the reading-impaired group made significantly more errors than the controls. The reading-impaired children's ability to use phonics skills (nonsense word reading) was also examined. There was a high correlation between the number of errors made on the phonics reading test and the number of errors made in responding to the rapidly presented stimuli in the auditory perceptual tests. The hypothesis that some reading impairments are related to low-level auditory perceptual dysfunction that affects the ability to learn to use phonics skills adequately is discussed.     

Child performance on discrimination tasks: Effects of amount of stimulus variation

Two independently conducted studies investigated stimulus variation effects on children's discrimination learning. The stimuli in the first study were generated by a conjunctive rule and were presented in pairs. Mean trials to criterion was significantly lower for the single-feature change treatment (17.4) than for the multiple-feature change treatment (29.9). Single-feature change-treatment transfer scores were significantly higher only for stimuli that differed in terms of one of the features. The second study not only replicated the initial finding concerning the single-feature change treatment but also found that students made more errors in reaching criterion when stimuli were generated by an exclusive disjunctive rule and were presented singly. For all tasks, the single-feature change treatment with stimuli presented in pairs was accompanied by fewer errors to criterion than the other treatments.     

Feedback and fidelity: Effects of contingent consequences on accuracy of imitation

Accuracy of imitation by sixty kindergarten subjects was examined using a task in which a female adult modeled a series of pegboard patterns and delivered accuracy-contingent feedback. Four methods of feedback and a nofeedback control were compared. All four feedback groups were more accurate than the control group. The feedback conditions were: positive only, negative only, positive and negative, and negative with correction. The last condition resulted in greater accuracy than the others, which did not differ. All groups, including the control, improved significantly over trials. Accuracy of performance on interspersed, nonfeedback trials was maintained by feedback to the other patterns. Finally, imitation of repeating stimulus patterns did not differ from performance with nonrepeating patterns.     

Conciliatory strategies and relative power

In an investigation of variations of a conciliatory strategy, 96 subjects, half female and half male, played a modified Prisoner's Dilemma in which their relative power, in terms of control over the other's outcomes, was less than, equal to, or greater than that of a simulated other. After 10 trials on which (s)he was 50% competitive, the other either did or did not send a handwritten note of general intent to be cooperative. In the second block of 10 trials, the other either was 100% cooperative or began with cooperation and stayed with it as long as the subject did not exploit. When the subject did exploit, the other made the competitive choice on the following trial as a form of retaliation, but followed this retaliation by a return to cooperation on the next trial so that there were never two consecutive competitive choices. During this second block, the simulated other always signaled in advance, with an explicit message, which choice (s)he was about to make. In a third block, the other was 100% cooperative in all conditions and sent no messages. As hypothesized, subjects whose power was equal to or less than that of the other were more cooperative in response to conciliation than were subjects whose power was greater than that of the other. Subjects who received the general note of intent were more cooperative than those who did not, but only in the equal and low power conditions. The subjects in the equal power condition who experienced retaliation were more cooperative than those who did not, but those in the unequal conditions tended to react negatively to retaliation. The results were discussed in terms of Osgood's (Peace Research Reviews, 1979, 8(2), 77–92) GRIT strategy and outcome control in interaction.     

Children's binary prediction of partially learnable sequences followed by an all-correct procedure

Six groups of 20 subjects each were run individually in a binary prediction situation with each alternative occurring equally often. Two age groups were employed; subjects were either in second or sixth grades. For one-third of the subjects at each age level, the events occurred in runs of either two or six; another third observed events which occurred in runs of either five or six; the other subjects received a random sequence of events. All subjects then received an additional 50 trials in which every prediction was correct. The results indicated some sensitivity to run length characteristics. Fewer errors of all types were made in the prediction of 5–6 sequences. The verbal reports and all-correct trial protocols revealed that at least the sixth graders employed some simple run length structure rules, although many instances of runs other than those presented in training occurred, showing much processing error. The results were discussed in terms of a general limited-capacity model of information-processing.     

Stimulus generalization following extradimensional and intradimensional training in educable retarded children

Five related experiments investigating stimulus generalization following go/no-go discrimination training of educable retarded children are reported. Experiment 1 employed an Extradimensional paradigm in which generalization testing was on the hue dimension following training on an independent (orientation) dimension. Following True discrimination training only 25% of children showed a decremental stimulus generalization gradient on the hue dimension, though all children exhibited flat gradients in Pseudodiscrimination and S+ only control groups. An increase in difficulty of the orientation discrimination in Experiment 2 did not increase the number of decremental gradients. In Experiment 3, children who exhibited decremental gradients in Experiments 1 and 2 underwent further generalization testing with modified stimuli to establish a symmetrical gradient peaked at a hue S+ to be employed in Experiments 4 and 5. In these experiments an Intradimensional paradigm was employed with S+ and S? stimuli drawn from the hue dimension. Excitatory control by S+ and inhibitory control by S? were demonstrated, as were inhibitory consequences of S? such as peak and area shift.     

A developmental study of pronouncing responses in the discrimination learning of words and pictures

Subjects at three age levels were administered picture pair or word pair discrimination lists. They pronounced or pointed as a method of choice, and they pronounced or pointed at the correct item (or remained silent) during rehearsal. The results indicated that with picture pairs, pronunciation facilitated learning as a method of choice and a type of rehearsal in nursery school Ss. For fifth grade and college Ss, there was no significant difference between pronouncing and pointing as a method of choice. However, spoken rehearsal was superior to control performance for fifth grade Ss. College Ss performed equally well in the control and pronouncing conditions, but pointing during rehearsal produced significantly more errors than pronouncing. Word pairs produced no significant pronunciation effects. These results were discussed within an internalization of speech perspective.     

Basic level and superordinate level categorization by autistic, mentally retarded, and normal children

Three experiments designed to test autistic children's nonverbal and verbal categorization abilities are reported in this paper. In the first two experiments, 14 autistic children were compared to 14 retarded and 14 normal children matched on verbal mental age. Their ability to categorize pictures from basic level categories and from biological and artifactual superordinate level categories was assessed using a matching-to-sample procedure. The three groups of subjects were similar in their performance. Basic level categorization was easier than more abstract categorization, and for all three groups, prototypicality played a role in categorizing superordinate level concepts; that is, children in all three groups made more errors categorizing peripheral examples. In the third experiment, a subgroup of 7 autistic children showed evidence that their lexicons were well organized and that they appreciated the meaning relationships among words at the superordinate level. These findings suggest that autistic children do not suffer a specific cognitive deficit in the ability to categorize and form abstract concepts, as has been previously suggested in the literature.     

Memory scanning of shapes,colors, and compounds: A comparison of retarded and nonretarded adults

Three experiments were performed to assess memory scanning of shapes, colors, and shape-color compounds by retarded and nonretarded people. Attributes comprising compounds provided either redundant or nonredundant information. Large retarded-nonretarded differences in reaction time were obtained. In contrast to previous reports of slow scanning of digits and nonsense shapes by retarded people, scan rates for shapes and colors did not differ between groups. Retarded subjects were not characterized by a deficient scan rate. Although compound stimuli required twice as many attributes in their repersentation as did simple stimuli, they were not scanned more slowly, indicating that per item scan rate is not determined by the number of attributes required to define each item. Both groups were able to exploit redundant relevant information to achieve faster processing than in simple conditions. Decision rules for rejecting compound stimuli comprised one, two, or more binary tests. Groups did not differ in speed of performing elementary binary test(s).     

The effects of a graduated stimulus change on the acquisition of a simple discrimination in severely retarded boys

Methods were compared for teaching severely retarded boys to discriminate the position of a 0.75-in. black square and to press the response key closest to it. Seven boys were given trial-and-error training; one learned the task. The six boys who did not learn were presented with a program of graduated stimulus changes. All but one acquired the performance, and he was under appropriate control during the program. When he reached the criterion stimuli, he reverted to a position-based response learned during trial-and-error training. Six similar subjects were presented with graduated stimulus training alone. All six learned the criterion discrimination with few or no errors. Both groups were tested for retention of the criterion performance 35 days after training was completed. Two boys who had near-perfect criterion discrimination performances showed no signs of retention after 35 days. These boys had a history of trial-and-error training.     

Short-term memory for a pure-tone stimulus among mentally retarded and nonretarded persons

Two studies were conducted to determine whether short-term memory performance differences between mentally retarded and nonretarded persons can be attrubuted to the operation of structural features, as contrasted with strategic control processes. The task—discrimination of intensity differences between two pure tones—was selected as one which would minimize specific strategy utilization. In the first experiment normal children, normal adults, and retarded adults were presented with a standard tone and then a comparison tone after an interval of 1, 5 or 10s. Difference limens and constant errors were computed over a substantial number of trials. Measures of intra-individual variability were also obtained. Clear age and IQ-related threshold differences were obtained. Difference thresholds increased over intervals for all groups. However, the critical interaction that would support a theory of differential decay of the memory trace was not obtained. A second experiment, procedurally similar to the first, was conducted using signal detection methodology. The major findings were: (a) groups differed in sensitivity (d′); (b) d′ decreased with increasing separation of standard and comparison tones; (c) d′ increased as the intensity differences between standard and comparison tones increased; and (d) retarded subjects did not alter response bias to changing task requirements Again, however, the interaction of groups and retention interval was not significant. Intelligence and age-related differences in the task occur early in the information processing sequence and appear to be of a perceptual nature.     

Eliminating selective stimulus control: a comparison of two procedures for teaching mentally retarded children to respond to compound stimuli

Selective stimulus control occurs when behavior fails to come under control of all characteristics of a compound stimulus after discrimination training. Two different assessment procedures, one used in prior research and the other incorporating incorrect stimuli (S - 's) which differed minimally from the correct stimulus (S+), were used to detect stimulus control deficits characteristic of selective stimulus control. The efficacy of two training procedures in eliminating selective stimulus control observed with three trainable mentally retarded children was evaluated in Experiment 1. A training procedure using S - 's that were minimally different from the S+ was designed to reduce the probability that stimulus discriminations could be based on stimulus characteristics other than experimenter-specified characteristics defining the S+. This procedure proved more effective in preventing and eliminating selective stimulus control as measured by both assessment procedures than an alternate discrimination training procedure that failed to impact the more stringent measures of selective stimulus control. Experiment 2 indicated that these improvements in stimulus control were not a function of varying degrees of difficulty between stimulus sets or of a prior history of discrimination training with the less effective training procedure. The need for better assessment procedures to detect selective stimulus control and suggestions for further improvements in discrimination training procedures are discussed.     

Control of children's observing responses by information feedback during visual discrimination learning

Four experiments examined the control of observing responses by information feedback during visual discrimination learning. Second-grade children participated in Experiment 1; kindergarten, second-, and fifth-grade children were subjects in Experiments 2 and 3, and grade 5 and adult subjects were tested in Experiment 4. In order to view the stimuli, subjects in Experiments 1, 2, and 3 activated lights in viewing boxes; in Experiment 4, stimulus fixations were measured using a corneal reflection technique. Fifth graders and adults observed the discriminative stimuli for longer times on trials following negative feedback than on trials following positive feedback; in contrast, kindergartener's observing was not affected by type of feedback. Second graders showed smaller and less reliable reactions to type of feedback than did older subjects. These results support the view that visual observing is controlled by cognitive processes associated with hypothesis testing.     

Impairments of nonverbal oral movements after left hemisphere damage: A followup analysis of errors

Acquisition of a task requiring the imitation of a series of nonverbal oral movements is most severely impaired in patients with aphasic disturbance. However, nonaphasic patients with left hemisphere damage also perform more poorly than patients with right hemisphere damage or normal control subjects. Analysis of the errors made on the multiple oral movements task reveals that left, but not right, hemisphere damage is highly associated with perseverative responses. Patients with right hemisphere damage do not differ significantly from normal control subjects in the acquisition of or in the type of errors made on the task. It is suggested that the left hemisphere plays an important role in the control of nonverbal oral movement production.