Douglas Friedrich

Academic self-concept and teachers' perceptions of normal, mentally retarded, and learning disabled elementary students

The self-concepts of educable mentally impaired, learning disabled, and nonhandicapped children were assessed using the Student Self-Evaluation (SSE), Teacher Evaluation Scale (TES), and How I See Myself (HISM) test. A Groups × Age × Sex analysis of covariance, with IQ effects statistically controlled, was computed for each measure. On the SSE, the groups were significantly different, with nonhandicapped students having better self-concepts than learning disabled students, and learning disabled students having better self-concepts than educable mentally impaired students. Teacher estimates of self-concept (TES) indicated that nonhandicapped students have better self-concepts than have handicapped students. For the HISM scores, there was a Group × Sex interaction, but no significant main effects; there was no consistent pattern to the interactions. The results suggest that handicapped children, as a group, have a lower self-concept than have nonhandicapped children. Implications for educational programming and future research are offered.

Exploratory behavior in down's syndrome and normal infants

Abstract Comparisons were made of 10 Downs syndrome and 10 normal 12-month-old infants of mouthing, manipulative and visual measures of exploratory behavior. Infants were familiarized with a bell and duration measures were obtained for each behavior. No differences in any explatory behaviors were evident during this phase. Next, infants were presented with the bell paired with 15 novel objects, one at a time. Both groups demonstrated a preference for novelty in each mode of exploration. The normal infants mouthed and manipulated novel objects for longer periods of time than the Downs syndrome infants. No differences were found for visual exploration. Response decrement occured to the novel objects for the Downs syndrome infants. Differential exploratory behavior is of interest because of its relationship to cognitive development.

Threshold measures of sensory register storage (perceptual memory) on normals and retardates

The method of limits was used to estimate the perceptual or immediate memory thresholds for a sample of 12 normals and 12 institutionalized retardates matched on CA and perceptual intactness. A stimulus array, composed of six digits in a circular pattern, was presented tachistoscopically. On the first trial, the duration of the array increased at 100-msec intervals beginning from a 100-msec base. After three consecutive correct responses were recorded, the array duration decreased (Trial 2) in 100-msec steps until three consecutive incorrect responses were recorded. The same procedure for the remaining six trials was followed, with the exception that 50-msec steps were used. A poststimulus cue immediately followed the offset of the stimulus array for a duration of 100 msec. The offset of the cue was followed by the S naming the digit that was indicated by the cue. Averaging over trials, the mean thresholds for normals and retardates were 424.861 and 1,538.194 msec, respectively. Following a logarithmic transformation of the data, a 2 (groups) by 6 (trials) repeated-measures analysis of variance revealed a practice effect for normals, but not for retardates, and superior performance of normals on all trials. The results were interpreted within Atkinson’s memory model.

Nonselective read-out from iconic memory in normal, borderline and retarded adolescents

Abstract The hypothesis that retarded individuals read-out information from iconic memory at a slower rate, relative to their CA matched peers, was tested. Three IQ groups (normal, borderline and retarded) were selected with 10 subjects in each group. A tachistoscope presented a stimulus array and a post-stimulus cue for 100 msec. each, separated by a variable interstimulus interval (ISI). This stimulus array consisted of 10 letters arranged on two horizontal rows. The post-stimulus cue was a circle which surrounded the position of the correct letter. Nine ISIs were used and ranged from −100 (cue before array) to 500 msec. A 3 × 9 repeated-measures analysis of variance revealed non-significant effects for IQ and the IQ × ISI interaction. A significant effect was found for ISIs (p

Relationship between perception (input) and execution (output)

15 brain-damaged and 9 non-brain-damaged retarded Ss were given the following visual-motor tasks: (a) the WISC Block Design subtest, (b) the WISC Block Design multiple-choice procedure presented by Birch and his associates, and (c) the MPD circle-diamond figures, incorporating pencil and block procedures. A combination of the Block Design subtest and the circle-diamond figures was successful in indicating Ss with execution (motor) or integrative dysfunctions. The multiple-choice procedure proved invalid as a technique for differentiating Ss with executive or integrative dysfunctions from Ss with visual perceptual difficulties. The results argue against the commonly held notion that perception is a unitary process. Rather, the findings suggest that failures on visual-motor tasks by mentally retarded Ss result primarily from faulty executive or integrative components.

Learning Disability Fact and Fiction

Based on approximately 1,600 referrals of learning disabled, educable mentally impaired, emotionally impaired, other disabled and regular students, 94 empirically derived formulas for assessment of learning disability were used. The most discriminating formula, which included WISC, WRAT and grade level variables, resulted in moderate coefficients. An external validity study supported the original research conclusions. Because of the modest discriminating ability of even the best empirically derived formula, additional defining referents/measures of the learning disability were described.

Visual‐motor test performance: Race and achievement variables

Tested rural Michigan black (N = 60) and white (N = 60) children of variant academic achievement on the Minnesota Percepto-Diagnostic Test for visual-motor skill development. The test, which consists of six gestalt designs for the person to copy, includes four measures of such skill development: Degree of copied design rotation and errors of separation of circle-diamond, distortion of circle-diamond and distortion of dots. In general, analyses that statistically controlled for intellectual level indicated that race was not a significant variable in the relationship of achievement level and visual-motor test performance. That is, such analyses resulted only in a significant achievement effect; low achievers, in comparison with high achievers, performed poorly on the copying test. Only with distortion of circle-diamond errors was a race interactive effect noted; i.e., black low achievers had significantly more errors than black high achievers, white low achievers or white high achievers. Results were discussed in relation to environmental determinants and symptomatology correlates.

Read-Out Times from Iconic Memory in Normal and Retarded Adolescents.

The method of limits was used to obtain an estimate of readout times for a sample of 12 normal and 12 retarded subjects matched on chronological age. The procedure required tachistoscopic presentation of a stimulus array (2, 4, or 6 digits) for a variable duration, followed by a post-stimulus cue. The subjects task was to recall the digit indicated by the cue. The results indicated that read-out time (a) increased as the number of digits increased, (b) was longer for retardates relative to normals, and (c) decreased with practice for both intelligence groups. The implications of a read-out deficit in retarded individuals were discussed.

Memory Performance of Young, Middle, and Old Adults.

Young, middle-aged, and older adults were assessed on tasks operationally defining short-term memory structural limitations and process abilities. The tasks were typical of previously related memory research with children and adolescents: monaural and dichotic word lists of variant association structure and rate of presentation. Although a number of minor chronological age-related differences were noted between monaural and dichotic word list performances, the findings indicated both structural capacity and organizational strategy deficiencies over successive adult age groups. In addition, older adults indicated significantly more heterogeneity of performance variance, both between and within age group comparisons. Results were summarized within the Cattell-Horn developmental model of fluid and crystallized abilities.

Comparison of intrusion errors and serial position curves on monaural and dichotic listening tasks: A developmental analysis.

Based on a repeated measurement study of 7-, 10-, 14-, and 17-year-olds with monaural and dichotic presentations of word lists varying in associative structure and presentation rate, intrusion and serial position dependent variables were analyzed. Intrusion analyses supported previous reports on word list recall; vis, 7- and 10-year-olds recalled fewer words from monaural and dichotic lists and had more intrusive errors than adolescents. Based on similar orders of report (strategies) for monaural and dichotic word presentations, serial position curves for the two types of presentation were compared. Within-age comparisons were strikingly similar. Between-age comparisons of monaural and dichotic presentation serial position curves support the notion that there are ontogenetic limitations in memory structure and control processes.