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.     

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.     

Input organization as a mediating factor in memory: A comparison of educable mentally retarded and nonretarded individuals

The effect of presentation context on the organization and recall of strongly related and weakly related words was examined in EMR adolescents and nonretarded fifth-grade children of the same mental age (131 months). In blocked presentation formats, subjects sorted words into experimenter-defined groups of four, in which the order of the groupings either changed from trial to trial (i.e., blocked-random), or was consistent across trials (i.e., blocked-consistent). In sort-prompt conditions, subjects were free to structure their own relationships among items during presentation, following instructions to form meaning-based groups (i.e., minimum-sort-prompt), or given explicit training in sorting categorization and sorting stability (i.e., maximum-sort-prompt). Both subject groups found the minimum-sort-prompt method to be as effective as the maximum-sort-prompt method for improving measures of recall and clustering relative to the blocked-random method. Nevertheless, nonretarded children showed higher levels of organization for strongly related items, and better recall and organization for weakly related items. Subsequent analyses suggested that the lower memory performance of the EMR individuals receiving weakly related items was the result of both inconsistent and poorly structured sorting schemes across trials.     

Selected parameters of response organization in mildly mentally retarded children

The purpose of this study was to investigate the effect of response organization on reaction time (RT) and movement time (MT) of mildly mentally retarded children. Two groups of 30 subjects each were formed: a retarded group 9 yr. of age and a normal group matched for chronological age. Subjects were randomly assigned to one of three precued conditions in which they were told that the forthcoming response would be performed with the right or left hand (precue hand), be to the right or left side (precue direction), or cross or not cross the body midline (precue midline). The retarded group performed significantly more slowly than the normal group on both RT and MT. Both groups, however, were able to utilize precued hand information as opposed to other precued variables, indicating that knowing which hand to use is important when organizing responses.     

Output organization in the free recall of mildly retarded children

Output organization in multitrial free recall of ‘unrelated’ lists can be quantified using measures of intertrial consistency or subjective clustering, the latter being based on subjective ‘categories’ revealed in a post-recall sort task. It has previously been shown with picture stimuli (Todman 1982) that recall and subjective clustering, but not intertrial consistency, increase with age for nonretarded children. In the present study, mildly mentally retarded children at three age levels were given the same task. Although recall increased with age, there was no age effect on subjective clustering or intertrial consistency. Output organization of the retarded groups was compared with that of nonretarded groups at three age levels. The nonretarded groups comprised previously tested children selected to equate each group with one of the three retarded groups on mean recall. Across all age levels, intertrial consistency was significantly (p < 0.02) higher for retarded groups.     

Knowledge and behavior relationships in the memory ability of retarded and nonretarded students

Twenty mildly mentally retarded adolescents were matched with two groups of nonretarded students, one of the same chronological age (CA 16) and the other of the same mental age (MA 9), to examine the influence of age and metamemory on recall. This was achieved using an adapted metamemory instrument which included relevant recall tasks. Recall scores showed that when tasks exhibited some organizational features, the retarded group was as accurate as their CA counterparts; when tasks were less organized, they responded much like their MA counterparts. Regression analyses indicated that, depending on task characteristics, chronological age emerged as a significant predictor of recall in certain situations, and in others, mental age accounted for more variance. Metamemory responses in one task accounted for more variance than either CA or MA.     

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.     

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.     

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.     

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.     

Visual novelty preference as a measure of recognition memory in moderately, severely, and profoundly retarded persons

A novelty preference method was used to examine memory processes in profoundly, severely, and moderately retarded persons. After viewing a photograph of a face for 30 seconds, subjects were shown the study face and a new one after intervals ranging up to 3 minutes. Data were obtained from 30 of 56 subjects with this method. Of the 30 subjects, 20 showed significant preference for looking at the new face in the test. Recognition memory as indexed by novel looking declined over the retention interval. Memory was stronger but decayed more rapidly for higher memorable (distinctive) faces. With refinement, the novelty preference method holds promise for the study of cognitive processes in nonverbal persons. But, since memory is being inferred from response preferences which reflect an induced motivational state, satiation, the relationship between this state and memory must be established.     

Some functional properties of iconic storage in retarded and nonretarded subjects

Four experiments, which examine some functional properties of iconic storage in mildly retarded subjects, are reported. Experiments I and III demonstrated that retardates report about three items, or one item less than normal subjects, after a single brief tachistoscopic exposure and that this span of attention was independent of size of array. Both normal and retarded groups reported more items correctly when arrays were arranged on two lines. Experiment II determined that exposure durations up to 250 msec did not influence the number of items reported by either group. Experiment IV compared the form of decay for both groups by cuing report of each of seven positions at five poststimulus delays. The presence of the typical W-shaped curve for both groups at all delays permitted the inference that items in iconic storage decay together rather than individually. Although quantitative differences existed between groups, in no case did intelligence interact with the manipulated variables. The results were discussed in relation to control processes and structural features within an information processing model of memory.     

Executive processing differences between learning-disabled,mildly retarded,and normal achieving children

This study examined possible executive processing differences between mildly retarded, learning-disabled, and normal achieving children. To this end, the groups were compared as to their ability to recall central and secondary words from base and elaborative sentences under conditions of high and low encoding effort. Executive processing was inferred from the children's ability to maintain optimal recall performance for central and secondary words. Groups were comparable in central recall, but differences in secondary recall occurred for the high- effort encoding condition. Qualitative differences related to the prioritizing of resources (as reflected in the correlation between central and secondary recall) and monitoring the transfer of information (as reflected from central and secondary recall insertions) were found between groups. The results were discussed in terms of an executive processing frame-work that views retarded children as suffering from inefficiencies related to the sharing of resources, whereas the learning-disabled children's inefficiencies were related to the discrimination of resources.The author is indebted to Karl Schemdli, Director of Special Education and Susan Swaim, Research Director, University of Northern Colorado Laboratory School, for their administration assistance in providing children for this study. The author is indebted to Dr. Jim Nicholes for his assistance in the data collection.     

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.     

Tower of Hanoi performance of retarded young adults and nonretarded children as a function of solution length and goal state

Three experiments were conducted with the Tower of Hanoi task to assess problem solving ability in 6-, 7-, 8-, and 10-year-old nonretarded children and mentally retarded young adults of varying maturational ages. In Experiment 1 we gradually reduced the number of moves required for solution until subjects could solve the 3-disk tower-ending problem. Although all groups experienced difficulty with the standard 7-move problem, all but the trainable retarded group readily solved the 6-move problem. The trainable group did not reach a comparable level of success until the 4-move problem. On the 7-move problem the retarded groups performed at the level of nonretarded groups that were maturationally $\text{1}\text{1}\text{2}$ to 3 years younger. An analysis of first moves indicated that subject groups differed in the strategies they used to solve the problems. In Experiment 2, practice effects were ruled out as a source of the superior performance on the 6- than on the 7-move problem. In Experiment 3, 7- and 10-year-old nonretarded children and mentally retarded young adults did not differ on 5-move problems in which configuration of the goal states was varied. A comparison of all 5-move problems judged to have the same depth of search requirements indicated that the tower-ending problems were significantly easier to solve than the partial-tower-ending problems, which in turn were easier than the flat-ending problems. A limited depth of search capacity sets boundaries on the use of sophisticated strategies and, to a large extent, accounts for the retarded groups' maturational lag.     

Labeling, rehearsal, and short-term memory in retarded children

A short-term memory task was used to explore the effects of verbal labeling and rehearsal on serial-position recall in mildly retarded 9- to 11-year-old children. A stimulus array consisting of seven cards depicting familiar animals was presented for seven trials. In Expt I, recall when subjects labeled the pictures as they were shown was compared to recall when no labeling occurred. Total recall was not affected, but for the older CA group primacy recall was hindered and recency recall was facilitated by labeling. In Expt II, three variations of rehearsal of the names to be recalled were compared. When prompting accompanied rehearsal, recall improved at both recency and primacy positions. When prompting occurred for the primacy positions only, recall was higher for these positions but not for other positions. These results support the view that verbal skills affect recall in mildly retarded children similarly to normal children.     

Comparison of selected gait parameters of trainable mentally retarded and nonretarded males

Although there were no significant differences in the single support phase of gait for 6 trainable mentally retarded boys (Mean age 9.6 yr.) and 6 nonretarded boys (Mean age 9.5 yr.), total gait time and time in double support were significantly different for the two groups, supporting previous research which showed gait was was deficient in trainable mentally retarded individuals.