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Biomedical subjects

N R Ellis

Publications and source records attributed to N R Ellis.

At least 19 recordsLinked to original sources
PubMed1992

The influence of physical fitness on automatic and effortful memory changes in aging.

A cross-sectional study was carried out in order to determine the influence of cardiovascular fitness on age-related declines in cognitive performance. Forty-eight volunteers were divided into Young (n = 13, 18-27 years), Middle-Aged (n = 22, 60-65 years) and Old (n = 13, 65-88 years) groups and tested on a battery of cardiovascular, pulmonary, hemodynamic, and biochemical tests in order to assess physical fitness. Cognitive performance was evaluated by a variety of memory tasks distributed along an automatic-to-effortful processing continuum. Memory for location and frequency of occurrence were selected as representative of automatic processing, whereas, an auditory free-recall task was selected as representative of effortful processing. Age-related performance declines were observed for the free-recall task, but no such age-dependent association was observed for frequency and location memory. With regard to the influence of physical fitness; the Middle-Aged and Older participants were divided into High and Low Fitness groups and significant differences were observed between these groups for the effortful but not the automatic memory tasks. These data suggest that the relationship between physical fitness and cognitive performance in old age is task dependent. Furthermore, the apparent prophylactic effects of physical fitness on effortful memory, do not appear to extend to cognitive tasks requiring less effortful processing.

Age Factors↗
PubMed1991

Automatic and effortful memory processes in elderly persons with organic brain pathology.

This study investigated the automatic and effortful memory encoding model of Hasher and Zacks (1979) and the potential it may hold for aiding in the differentiation between aging-related memory decline and dementia. College students, normal elders, and dementia patients were compared on a 96-item picturebook task utilizing measures of free recall, recognition accuracy, memory for location, and memory for frequency. There were no differences between students and elders on any of the dependent measures. However, differences were found between elders and patients on each measure, and a discriminant function correctly classified the two groups with 93.3% accuracy. Subsequent discriminant analysis found patients could be correctly classified into diagnostic subgroups, i.e., dementia of the Alzheimer's type (DAT), multi-infarct dementia (MID), and Korsakoff's disease (KD) with 80.8% accuracy. The model holds promise as a guide for clinicians who are asked to make differential diagnoses of memory-impaired individuals.

Adolescent↗
PubMed1991

Memory for spatial location in retarded and nonretarded persons.

Item memory and memory for spatial location were examined in college students, mildly retarded persons and moderately retarded persons. They performed under semantic or nonsemantic encoding instructions to remember pictures presented in a large book. Recall and relocation (unexpected) tests followed immediately after studying the pictures and, again, 24 h later. Mildly retarded persons were deficient in memory for items (effortful processing), but not in memory for location (automatic processing). Moderately retarded persons were deficient in both types of memory. Additionally, there were IQ-related differences in the long-term memory of location information, as well as item information. Location memory, as opposed to item memory, was shown to be (1) sensitive to encoding instruction, (2) insensitive to differences in intelligence, and (3) more sensitive to long-term forgetfulness.

Adolescent↗
PubMed1991

Further evidence for cognitive inertia of persons with mental retardation.

Two experiments confirmed and extended earlier research (Ellis, Woodley-Zanthos, Dulaney, & Palmer, 1989) showing that persons with mental retardation are more rigid than persons without mental retardation. In Experiment 1 subjects read Stroop words, practiced naming the colors of Stroop words, and then read the Stroop words again. Postpractice reading interference was related to amount of practice, and the interference effect was much greater in persons with mental retardation. We hypothesized that the practice led to automatization of a reading suppression response that had greater cognitive inertia for persons with mental retardation and, therefore, had a greater effect on postpractice reading for them. This cognitive inertia effect was shown to be quite durable in persons with mental retardation, lasting more than 3 months for 10 of 13 subjects. The effect disappeared within a month for persons without mental retardation.

Adolescent↗
PubMed1990

Is memory for spatial location automatically encoded?

Naveh-Benjamin (1987, 1988) has shown that memory for spatial location does not meet the criteria for automatic encoding as claimed by Hasher and Zacks (1979). Age, intention, concurrent processing demands, practice, strategies, and individual differences affected memory for location. These variables should have affected effortful but not automatic processing. The experiments reported in the present paper, in which a different task was used, showed that intention, practice, and concurrent processing demands did not affect memory for location. I concluded that (1) the location task used by Naveh-Benjamin included effortful subtasks and also incidental cover or concurrent processing tasks that interfered directly with performance, and (2) the variables that he manipulated may not have affected the encoding of location. The need to differentiate processes from task performance in analyzing the automaticity issue is discussed. The dominant mode for remembering location is automatic, but such information may also be remembered voluntarily.

Adult↗
PubMed1989

Memory for spatial location in children, adults, and mentally retarded persons.

Two experiments extended earlier research showing age- and intelligence-invariance in memory for spatial location. Second and sixth graders, college students, and mildly retarded persons relocated pictures after looking through a 100-picture book. There were no differences due to age, IQ, or instruction (intentional or incidental) in location memory; there were differences in picture recall. In a second experiment persons with Down syndrome, as a group, were less accurate in location memory than were college students, but many individuals performed as accurately. A 3-month follow-up on the subjects with Down syndrome revealed greater consistency in location memory than in recall. Overall, the results show that young children and mildly mentally retarded persons process spatial location information as well as do college students. Some, but not all, of the more severely mentally retarded persons had deficits in processing memory for location. All persons with mental retardation had deficits in effortful processing as reflected by free recall.

Adolescent↗
PubMed1989

Automatic-effortful processing and cognitive inertia in persons with mental retardation.

A modified Stroop Color-Word Interference Test (Stroop, 1935) was used to assess automatic-effortful processing in persons with mental retardation and college students in three experiments. In Experiment 1, retarded persons experienced greater Stroop interference than did college students. This was attributed to a failure of control (effortful) processing needed to suppress the automatic reading responses of retarded subjects. In Experiments 2 and 3, all subjects practiced the Stroop color-naming task over three or four daily sessions. Changes in Stroop interference over practice were viewed as reflecting automatization of the suppression of the reading response. Both groups automatized the suppression response at about the same rate, but the automatized responses had far greater and more durable suppression effects for retarded subjects. This persistence of automatized responses, which were no longer adaptive, was described as cognitive inertia, a phenomenon similar to cognitive rigidity as defined by Kounin (1948).

Adolescent↗
PubMed1987

Developmental aspects of memory for spatial location.

The purpose was to show whether or not the encoding of location met criteria defining an automatic process (L. Hasher & R. T. Zacks, 1979, Journal of Experimental Psychology: General, 108, 356-388; 1984, American Psychologist, 39, 1372-1388). Among other criteria, automatic processes are not expected to show developmental changes beyond an early age, to be unrelated to intelligence level, and to be unaffected by instructions. In the first experiment preschool through sixth-grade children were compared on a 40-picturebook task following incidental (remember the names of pictures) or intentional (remember location) instruction. Subjects viewed and named pictures in sets of four, arranged in quadrants in the opened book, and then attempted to recall names of the objects pictured and to relocate pictures on blank pages. In the second experiment, second and sixth graders, college students, elderly persons, and mentally retarded persons were compared on a 60-picturebook task following either incidental or semantic incidental instructions (give the function of objects pictured). Memory for location was invariant across age groups and intelligence level. The only exception was that 3 and 4 year olds were more accurate following intentional instructions. Otherwise there were no differences between intentional and incidental instructions. Semantic instructions resulted in slightly more accurate locations. The results were interpreted as supportive of the Hasher and Zacks' automaticity hypothesis.

Child↗
PubMed1987

Automatic and effortful processing by mentally retarded and nonretarded persons.

Automatic and effortful processing by brain-injured and cultural-familially mentally retarded and nonretarded persons were compared in a letter priming task. Both retarded groups responded considerably slower than did the nonretarded group. Inhibitory effects due to a prime stimulus and facilitative effects following brief presentations of prime stimuli were similar for all groups. Facilitative effects remained at the same level for the nonretarded group but clearly continued to increase for the retarded groups along the longest presentation intervals. The findings were interpreted as showing similar automatic processing effects in all groups. Effortful processing by retarded persons, on the other hand, was slower to develop and possibly greater than that by nonretarded persons.

Adolescent↗
PubMed1985

The effects of exercise on the health, intelligence, and adaptive behavior of institutionalized severely and profoundly mentally retarded adults: a systematic replication.

Institutionalized severely and profoundly mentally retarded adults participated in a 7-month program of rigorous aerobic-type exercises. The effects of the treatment on the physical fitness, intelligence, and behavior of subjects were assessed. Fifty men and women were matched in pairs based on IQ, CA, and sex and assigned randomly to an experimental (E) or control (C) group. Those in the E group met 3 hours per day, 5 days per week and received a treatment that consisted of an exercise program that included jogging, running, dance-aerobics, and circuit training. The C group continued their normal institutional training programs. The treatment produced significant improvement in the cardiovascular efficiency of subjects; however, no changes in intelligence or adaptive behavior were obtained. Although standardized tests reflected little improvement in psychological or behavioral variables due to treatment, subjective reports suggest that exercise training may serve as a more practical habilitation program for severely and profoundly mentally retarded individuals than those typically employed in institutional settings.

Adolescent↗
PubMed1985

Structural memory deficits of mentally retarded persons.

Short-term memory of mentally retarded and nonretarded persons was compared in four experiments on the Brown-Peterson task in an attempt to relate short-term memory deficit to control or structural processes. Type of stimulus, pictures and letters, was varied along with encoding time. On pictures, with liberal encoding time, rate of forgetting did not differ. Retarded groups forgot letters more rapidly after limited encoding time. Increases in encoding time improved retention for retarded persons, but this variable did not normalize forgetting rate. In a direct comparison, retarded persons retained pictures better than letters. The converse was true for nonretarded persons. Evidence for both encoding and storage deficiencies of retarded persons was found. Differences in memory were found under conditions that precluded the use of voluntary cognitive strategies. These differences were interpreted as evidence for structural memory deficits of retarded persons.

Adolescent↗
PubMed1985

Note on the recruitment of subjects for mental retardation research.

Analysis of questionnaires mailed to 42 distinguished mental retardation researchers suggests that many of them feel handicapped by existing subject recruitment policies. Cited frequently as a major impediment was the time delay attending the securing of parental consent.

Human Experimentation↗
PubMed1985

Short-term memory for pictures and words by mentally retarded and nonretarded persons.

Mentally retarded and nonretarded persons were compared in a Brown-Peterson short-term memory task for the retention of words and pictures over intervals up to 30 seconds. The retarded subjects forgot more rapidly over the initial 10 seconds. They also retained pictures better than they did words; the nonretarded subjects retained these stimuli equally well. The results were theoretically interpreted as reflecting a structural memory deficit in retarded individuals, who were viewed as having greater facility with an imaginal memory code than with a verbal code. Transforming information from one code to another may also have been more difficult for retarded persons.

Adolescent↗