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.     

Automatic and conscious processing in retarded and nonretarded adolescents

Educable mentally retarded and nonretarded adolescents participated in incidental learning tasks that emphasized the utilization of processes that were consciously controlled but not deliberately aimed at memory (Experiment 1). Retarded individuals' performance on a standard recognition test was equivalent to that of nonretarded subjects following phonetic encoding and nonstrategic encoding, but was deficient following semantic encoding. Retarded subjects also demonstrated a lower level of performance on a rhyme recognition task. In Experiment 2, retarded subjects provided a pattern of responding identical to that of nonretarded subjects on a picture-word interference task designed to assess automatic processing. The two groups produced equivalent levels of semantic activation. It was argued that the results of the two experiments indicate deficient semantic processing on the part of retarded individuals relative to that of nonretarded individuals that cannot be accommodated by a structural-deficiency model, a developmental-lag model, or a hypothesis that predicts intelligence-related differences only when the task involves the use of deliberate mnemonic strategies.     

Influence of item identification on the memory performance of mentally retarded and nonretarded adults

The role of item identification in the memory performance of mentally retarded and nonretarded adults was examined by varying the identification and memory parameters of a sequential same-different task. In Study 1, retarded subjects' identification ability was demonstrated to be less efficient than nonretarded subjects' ability. In Study 2, target duration and interstimulus interval were varied. Memory performance differed between groups, and the memory deficit for retarded subjects was demonstrated to be independent of their identification deficit. The target durations in Study 2 were relatively brief, and in Study 3, the target duration was increased to insure that all subjects could identify the target. Mentally retarded subjects were demonstrated to have a memory deficit. The results were discussed in terms of possible sources of the memory deficit.     

Memory for Objects and Faces by the Mentally Retarded and Nonretarded

Visual recognition skills of 26 mentally retarded high school students were compared with the skills of two groups of nonretarded students. All groups were taught to recognize 32 target faces and objects and were retested 1 week, 1 month, and 2 months later. The counterintuitive findings were that there were no significant differences between the retarded and nonretarded groups in memory for faces on any of the retest trials. All groups remembered faces significantly better than they did objects and remembered more of the pictures at 1 week than they did at 1 month or at 2 months. There was no significant loss over time in memory for faces. Relative to nonretarded subjects, the retarded subjects exhibited deficits in encoding and remembering objects but showed no such deficits in encoding and remembering faces. The results suggest that different configurational features may be used to encode objects as opposed to faces.     

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).     

Behavioral expectations of retarded and nonretarded children

Two experiments were conducted to examine the effect of the mental retardation (MR) label on impression formation among retarded and nonretarded children and adolescents. The first experiment, conducted with nonretarded children in a mainstreamed school, indicated that they have pessimistic expectations of retarded children with regard to cognitive and ability-related behaviorsand, to a lesser extent, social behaviors (i.e., getting married). However, their reactions were not as pessimistic nor as “patronizing” as were those demonstrated by college students in previous research. In the second experiment, mentally retarded adolescents indicated that they also have negative behavioral expectations of retarded children, however, their self expectations were negative only for social behaviors. The results suggest that, among retarded persons, the expectations associated with the MR label are negative for social behavior, but apparently less pessimistic for cognitive and ability related tasks.     

Control in memory for movement cues by mentally retarded children

The study was designed to determine the desirability of providing external prompts (1) to use a mnemonic to enhance accuracy of recall and (2) to use response 'priming' in memory for spatial location by mentally retarded persons. Two groups of 40 mentally retarded boys and girls and two groups of 40 MA-matched nonretarded children were compared for accuracy in the recall of movement on an arm-positioning task. No differences were found between mentally retarded subjects and MA-matched subjects treated under the same conditions. However, all groups were unable to make spontaneous control adjustments to accommodate the covert manipulations made just prior to recall. By providing response primes, appropriate performance adjustments were made by all groups, resulting in a significant improvement in accuracy of recall. These findings serve to reaffirm earlier reports showing remarkable similarity between the mentally retarded and MA-matched nonretarded subjects.     

Recognition memory in mentally retarded persons

The continuous recognition memory of retarded and normal subjects was assessed. The stimuli were magazine pictures, arranged so that lags of up to 250 pictures occured. The overall performance of the retarded subjects was poorer, in terms of hit rate or d′. However, the differences were present at 0 lag and the slopes of the forgetting curves were similar in both groups. It was concluded that differences between these subjects were due to a perception related process and not to memory.     

Do the mentally retarded have poor memory?

The hypothesis that mentally retarded persons have a short-term memory deficit whixh is due to inadequate rehearsal strategies is reexamined. A reevaluation of results of a number of experiments suggests that normal and retarded persons differ on short-term memory tasks, and the superiority of normals is present from the time of initial stimulus exposure. While some evidence for slope differences in retention curves is found in a few tasks, it is not strong support for memory differences. The hypothesis that “memory” differences are due to differential encoding as a result of more adequate rehearsal by the normal subjects is unacceptable. If this were the case, some differences in slope of retention curves could be expected unless rehearsal beyond the encoding stage was totally precluded. The review points to a need for an empirical reevaluation of the issue with a full recognition that deficits in particular processes may characterize some retarded persons and not others.     

Performance of retarded and nonretarded adolescents when processing relevant and irrelevant information.

The information-processing performance of 12 retarded and 12 nonretarded adolescents was compared. Using reaction time keys each subject classified color words, secondary color words, non-color words, non-sense syllables, and stick figures according to the color of ink in which each stimulus was presented. Reaction time of the nonretarded subjects was significantly faster than that of retarded subjects; color words and secondary color words significantly interfered with processing performance as measured by correct reaction time. The results indicate that the Stroop task interferes with response initiation rather than memory retrieval and that the locus of interference for retarded and nonretarded subjects is equivalent.     

Developmental auditory agnosia in the severely retarded: A further investigation

The hypotheses were investigated that (a) ability to recognize the auditory perceptual stimuli for familiar events is a developmental correlate to language acquisition and (b) the low functioning mentally handicapped suffer from auditory agnosia and are impaired in this ability. The subjects were 42 nonretarded children of ages 3 through 6 and 53 severely and moderately retarded, noninstitutionalized students. The retarded subjects were matched by mental age to the chronological age of the nonretarded children. The stimuli were 49 environmental sounds; the task consisted of sound-and-picture matching-to-sample. Group membership and developmental age were the factors in an analysis of variance design. The results revealed a strong effect of developmental age (p <. 0001). The effect of group was not significant, indicating that auditory agnosia may not be common among the lower functioning retarded. The assumption that agnosia may be a major factor underlying the language disability of the severely retarded was reexamined. It was suggested that the severely retarded achieve the requisite perceptual-semantic knowledge base for language too late, after the critical age for spontaneous and efficient language learning has passed.     

Mnemonic strategy instruction in coding, processing, and recall of movement-related cues by mentally retarded children

The purpose of study was to examine the differential coding and processing characteristics of two movement cue types in the investigation of the short-term memory of mentally retarded and nonretarded children. The central focus of the study was to determine the effects of formal instruction in the use of a mnemonic versus no instruction with both types of cues in a memory for movement paradigm. The investigation was conducted across two experiments. The main conclusion drawn from Exp. 1 was that movement 'location' cues were coded, processed, and retained by both the mentally retarded and the nonretarded children, but only the former required instruction in the use of a mnemonic to achieve accurate recall. Exp. 2 was fundamentally a replication of Exp. 1 with the exception that movement 'extent' cues were maintained reliable. The results were similar but not exactly the same as those of Exp. 1. Only the mentally retarded children given mnemonic instruction appeared to code, process, and retain movement 'extent' cues over time. The net result of the two experiments was that formal instruction in the use of a mnemonic was of benefit to the mentally retarded subjects and was not necessary for nonretarded subjects to achieve the same level of movement accuracy.     

GENERALIZATION AND TRANSFER BETWEEN COMPREHENSION AND PRODUCTION: A COMPARISON OF RETARDED AND NONRETARDED PERSONS

The study compared the acquisition, generalization, transfer, and maintenance of language comprehension and production responses by persons at two IQ levels: mentally retarded (N = 10) and nonretarded (N = 10). The two levels of the IQ Level factor were combined factorially with two levels of a Training Condition factor: Comprehension-Production and Production Only. Participants in the former groups were trained sequentially to (a) comprehend coin labels by pointing, and then (b) produce verbally the correct coin label. Participants in the Production Only groups were trained on the latter response only. A three-factor mixed design with one repeated measure plus a multiple baseline across coin responses was employed. Results indicated that both mentally retarded and nonretarded subjects attained a high level of acquisition and maintained their performance on 1- and 4-week follow-up tests. No difference occurred between mentally retarded and nonretarded participants in magnitude of acquisition, but the mentally retarded groups took approximately three times as many trials to complete training. Data also suggested, contrary to past research, that generalization from comprehension to production was bidirectional, with no difference in magnitude between mentally retarded and nonretarded subjects. Transfer from comprehension to production occurred in both nonretarded and retarded subjects; comprehension training facilitated a savings of trials in production training. These results show that language differences between retarded and nonretarded persons are quantitative rather than qualitative as some past research may have suggested.     

Tic-Tac-Toe performance as a function of maturational level of retarded adolescents and nonretarded children

Two groups of retarded adolescents, differing from each other primarily in IQ (and mental age), were compared with two groups of nonretarded children, differing from each other in chronological age (and mental age), on a modified tic-tac-toe game. The mental ages of the retarded and nonretarded groups were approximately the same. It was found that the slope of performance improvement with increasing maturational level was the same for both subject groups, but the performance of the retarded adolescents was approximately 1.5 years behind mental age expectations, as derived from the performance levels of the normal children. These findings support previous suggestions of a major retardate deficit in tasks requiring logical foresight.     

Breakdowns in flexible use of information: Intelligence-related differences in transfer following equivalent learning performance

Groups of retarded and nonretarded children were investigated as they learned three rules underlying problems adapted from the Raven Progressive Matrices Test: rotation, imposition, and subtration. The interest was in evaluating group differences in the ease with which the original set of rules was learned and the flexibility with which these rules were transferred to modified contexts. In the case of either learning or transfer, the metric of performance was the amount of aid, specifically the number of computer-generated graduated hints, needed for each subject to solve the problems. The groups were matched on their entering competence to deal with the rules under scrutiny, and also on mental age. No group differences were obtained as the subjects learned the original set of rules. However, on subsequent occasions when required to make flexible use of those rules, clear group differences emerged; and those differences increased as the similarity of the training and test contexts decreased. The results were seen as consistent with theories that emphasize transfer flexibility as one potential source of individual and comparative differences in intelligence.     

Availability and accessibility of information in the semantic memory of retarded and nonretarded adolescents

The availability of semantic information in storage and the accessibility of that information for retrieval were studied in retarded and nonretarded adolescents. In Experiment 1, 40 normal and 40 CA-equivalent (mean, 15 years) retarded subjects were required to retrieve information from semantic categories as well as to judge whether specific items were members of a given category. The results showed large IQ group differences on the retrieval task which could not be wholly accounted for by the items available in storage. Experiment 2 was designed as an attempt to remediate this retrieval deficit by introducing an organized retrieval plan consisting of subcategory cues. This organization facilitated retrieval as long as it was experimentally provided. Retrieval returned to its original level, however, when the cues were withdrawn. It was concluded that retarded persons had an accessibility deficit in addition to an availability deficit; one aspect of this accessibility deficit involved the failure to use spontaneously mnemonic strategies that were consistent with the semantic organization.     

Social problem solving and mother-child interactions of educable mentally retarded children

Mothers of retarded children and nonretarded children were observed and videotaped as they interacted with their own child in a seminaturalistic situation, requiring teaching, cooperation, and free play. The child's social problem-solving abilities were assessed independently. The Vineland scale was employed to provide some convergent evidence of social problem-solving as a component of social competence. Twelve educable mentally retarded and 19 nonretarded 10-year-old children and their mothers comprised the sample. For the mentally retarded group, it was found that the higher maternal directiveness, the lower the child's social problem-solving skills. Mothers who often gave the child opportunity for decision-making and social influence had children with higher problem-solving skills. The retarded children produced significantly fewer different strategies for solving social problems, but gave a wider range of strategies than has been found in previous research. There was some support that social problem-solving skills are related to social maturity.     

Levels of processing and memory in mentally retarded and nonretarded persons

Individual differences in memory were examined from the levels of processing perspective. Mentally retarded persons were expected to be more superficial processors. The recall of nonretarded and two IQ levels of retarded young adults was compared following the presentation of pictorial stimuli with either a shallow processing, deep processing, or control orienting task. Shallow processing was induced by directing subjects to name the colors of the pictures. In the deep processing condition, subjects were told to say what the pictured object was used for. In the control condition, they were directed to look at the pictures. The stimuli were presented as an incidental learning task. Encoding condition was a between-subjects variable. Nonretarded subjects remembered more overall than did the two retarded groups, which did not differ. At each intelligence level, more stimuli were remembered in the deep processing condition than in the shallow condition. There was no interaction of intelligence level with encoding condition. The hypothesis that retarded persons process at a more superficial level was not supported. A “spread of encoding” deficit in retarded persons is favored to explain the recall differences obtained in this experiment.     

The Ability to Encode Facial and Emotional Expressions by Educable Mentally Retarded and Nonretarded Children

The object of the present study was to investigate whether 20 educable mentally retarded (EMR) children matched for verbal mental age on the Peabody Picture Vocabulary Test (PPVT; Dunn, 1965) with 20 nonretarded (NR) controls were adept in identifying emotional facial expressions and producing the equivalent word adjectives. I also reassessed the relationship between the phase of identifying facial expressions (i.e., happy, sad, angry, and scared) and the phase of producing emotional word adjectives, consisting of 16 emotional linguistic constructions (4 short stories for each of the adjectives) between higher in verbal ability educable mentally retarded (HEMR) children and higher in verbal ability nonretarded controls (HNRC) and between low in verbal ability educable mentally retarded (LEMR) children and low in verbal ability nonretarded controls (LNRC). There were no significant differences between EMR and NR children in general, despite the fact that EMR children had deficits in receptive linguistic competence.