Biomedical subjects

W A Sparrow

Publications and source records attributed to W A Sparrow.

29 records · Page 2Linked to original sources

PubMed1997

Visual discrimination and motor reproduction of movement by individuals with mental retardation.

Visual discrimination and motor reproduction tasks involving computer-simulated arm movements were administered to 12 adults with mental retardation and a gender-matched control group to examine whether inadequacies in visual perception account for the poorer motor performance of individuals with mental retardation. In the discrimination phase subjects judged whether simulated arm movements were either of greater or lesser extent or shorter or longer in duration, respectively, than those of a standard display. In the reproduction phase accuracy in reproducing the movement in the standard display was measured. Results indicate that error in discriminating extent and duration was significantly greater for the individuals with mental retardation, who were also less accurate and more variable in matching the extent and duration of the standard displays. These outcomes implicate both perceptual and motor-reproduction inadequacies in skill acquisition for these individuals.

Adult↗

PubMed1994

The coordination and control of human creeping with increases in speed.

Changes were documented in the inter-limb and intra-limb timing of well trained adult males creeping at increasing speed on a motor-driven treadmill. A power function (y = axb) showed a good fit to hand and foot stride and support duration (y) and speed (x), a finding that parallels the changes expected in normal upright walking. Similarly, limbs of the same girdle maintained a half-cycle phase lag as speed increased. Swing duration, however, showed cyclical changes with increasing speed, a phenomenon not previously reported either for quadrupedal gait or normal upright gait. Ipsilateral hands and feet abruptly changed their phase-lags at a constant percentage of maximum speed in a manner similar to gait transitions observed in quadrupedal species. Explanations for these transitions were suggested, such as physical constraints on the speed of limb movement and the organism's biomechanical adaptation to increased metabolic energy expenditure.

Adult↗

PubMed1994

Energy expenditure and motor performance relationships in humans learning a motor task.

The ability of human subjects to learn minimum energy-demanding variants of biological motion was examined in three adult males trained to walk on hands and feet (creep) on a motor-driven treadmill at constant speed (0.64 m/s) for 16 3-min trials. Two subjects systematically decreased oxygen consumption and heart rate over trials. Following this acquisition phase, subjects completed walking and creeping trials at positive and negative treadmill grades and selected a freely chosen creeping grade that felt "most comfortable." One subject selected a grade that was more efficient than those imposed. Oxygen-consumption curves for walking and creeping converged with increasing positive grade, indicating that increased grade influences the metabolic energy viability of the task (creeping or walking). The acquisition data provide empirical support for the "principle of least effort" and lend support to the concept of a "comfort mode" in the execution of motor tasks.

Adult↗

PubMed1993

Intelligence and motor skill acquisition by discrimination learning.

This experiment investigated the relation between intelligence and acquisition of motor skill using predictions from Zeaman and House's 1963 attention theory. 20 undergraduate students and 20 subjects of low IQ (WAIS-R Full Scale IQ range 50 to 73, M = 60) made linear positioning movements of long and short amplitude to the left and right of a central starting position. Four conditions (right-long, right-short, left-long, left-short) were created by specifying the corresponding target area on the positioning apparatus. One or both of the paired cues were varied, i.e., left, right, long, or short, while the dimensions of direction and amplitude remained unchanged across conditions. A shift from one condition to the next followed a criterion response of four consecutive movements to the target area. Results supported the hypothesis that subjects of low IQ would require more trials to criterion than subjects of normal IQ across all conditions of direction and extent. There was qualified support for the hypothesised interaction between intelligence and cue shifts. The practical implications and theoretical significance of these findings are discussed.

Adolescent↗

PubMed1993

Effect of physical exercise on the performance of cognitive tasks.

This experiment examined the effect of physical exercise on measures of cognitive performance, Raven's Matrices, and an adaptation of the revised WAIS arithmetic subtest. We also tested the inverted-U hypothesis of an interactive relation between exercise-induced arousal and cognitive performance. 50 physically active men were assigned to five groups (n = 10) of equal physical fitness based on predicted maximum oxygen uptake. Three exercise groups undertook bench stepping at mean power outputs of either 47, 75, or 120 watts. One control group played Bingo and another control had no activity. There was no change in the Raven's Matrices scores pre- to posttest intervention, neither were there any between-group differences either pre- or posttest. The arithmetic scores were significantly higher over-all (p < .05) on the posttest, but there were no reliable differences between groups either pre- or posttest. These results suggest that short duration (6 min.) aerobic exercise has no effect on cognitive performance. This finding supports the majority of previous studies that used step-up tasks to examine the relation between physical exercise and cognitive performance.

Adult↗

PubMed1993

Constraints on the participation of individuals with mental retardation in mainstream recreation.

A questionnaire was designed to investigate the influence of skill level, behavioral characteristics, and labeling upon attitudes toward the participation of individuals with mental retardation in a recreation activity. The respondents were 320 members of 12 private tennis clubs. High multiple correlations between the predictor variables, attitude toward the behavior, and subjective norm, with behavioral intention supported the model of the theory of reasoned action. Attitudes, subjective norms, and behavioral intentions toward individuals with mental retardation were favorable regardless of the label assigned and perceived skill level. Perceived behavior of the target person, rather than skill level and label, was the more salient influence upon attitudes, subjective norms, and behavioral intentions.

Adolescent↗

PubMed1992

Performance on trials without knowledge results (KR) in reduced relative frequency presentations of KR.

Following Salmoni, Schmidt, & Walter's (1984) discussion of knowledge of results (KR) as a variable influencing learning, the effect of varying relative frequency of KR while holding absolute number of trials constant was examined. In two experiments, the same treatment groups were compared in acquisition, retention (after 2 min and 24 hr), and on their pattern of responses on the sequence of no-KR trials following a KR trial. In Experiment 1, differences between groups in acquisition were consistent with the number of KR trials received, and there were no differences between groups in either of the retention conditions. Experiment 2 replicated Experiment 1 with a more difficult task. There were no between-group differences in acquisition. In Retention 1, the 100% and 33% relative frequency groups outperformed the less frequent KR groups, whereas in Retention 2, this trend was reversed. The findings from Experiment 2 provide qualified support for the hypothesis that reduced relative frequency of KR in acquisition facilitates performance in retention. The pattern of responses on the sequence of no-KR trials following a KR trial were consistent with Adams' (1971) perceptual-trace decay hypothesis.

Journal Article↗

PubMed1989

Creeping patterns of human adults and infants.

The patterns of swing and support for the hands-and-feet or hands-and-knees gaits (creeping) of human adults and infants are compared based on data from a number of studies. Human infants show considerable variability in their creeping gait patterns, whereas adult patterns are less variable and fairly consistent after a few minutes of practice. Creeping on hands-and-knees appears to dictate a gait pattern characteristically different from creeping on hands-and-feet. The highly inefficient nature of adult creeping supports the view that our early hominid ancestors were poorly adapted to quadrupedal locomotion. Data obtained from high-speed film analysis of human creeping patterns show that the number of foot lengths per stride in creeping is about twice that for normal upright walking at the same speed. The support pattern of human creeping is different from that of nonhuman primates. These findings are discussed in the context of debate concerning the origin of the Laetoli hominid footprints and the knuckle-walking hypothesis.

Adult↗

PubMed1987

Mechanical efficiency and metabolic cost as measures of learning a novel gross motor task.

"Efficiency, " or economy of movement with respect to energy expended in achieving the goal of the task, is implicit in many definitions of skilled performance. This study examined changes in mechanical efficiency and transport efficiency on a novel gross motor skill. The subjects were 5 physically fit adult males who were asked to perform 20 3-min trials walking on hands and feet (crawling) on a motor-driven treadmill at constant speed (0.76 m/s). Transport efficiency, the metabolic cost of transporting the body mass a given distance at constant speed, improved significantly over practice trials. Mechanical efficiency, derived from the mechanical power output of individual body segments, showed an overall improvement of 13.7% by the last day of practice. Even though this improvement was not statistically significant it appears to be greater than that expected due to physiological training effects. The efficiency measures correlated significantly with changes in limb kinematics. It was concluded that with practice subjects tailored their movement pattern to produce energy efficient adaptations to task constraints. These findings provide empirical support for theoretical perspectives that have emphasized biological principles in the organization of motor coordination and control.

Journal Article↗

PubMed1983

The efficiency of skilled performance.

The observed ease or effort of performance has traditionally been considered an integral part of any definition of skill (e.g., Guthrie, 1935). Empirical investigations of skill learning and performance have, however, largely ignored the effort or efficiency with which the movement is performed. This situation has arisen despite the fact that in many skills, particularly athletic endurance events or industrial work tasks, efficiency of performance may be essential to the goal of the task. This paper focuses on the energy demand of various skills and its relationship to issues of learning, performance, and individual differences in preferred rhythm. It is shown that across a variety of tasks the individual's freely chosen work-rate is the most efficient. The significance of preferred rhythm to theoretical perspectives on rhythmic activity is discussed.

Journal Article↗

PubMedDate not supplied

Ageing effects on knee and ankle joint angles at key events and phases of the gait cycle.

The objective of this research was to determine whether joint angles at critical gait events and during major energy generation/absorption phases of the gait cycle would reliably discriminate age-related degeneration during unobstructed walking. The gaits of 24 healthy adults (12 young and 12 elderly) were analysed using the PEAK Motus motion analysis system. The elderly participants showed significantly greater single (60.3% versus 62.3%, p < 0.01) and double ( p < 0.05) support times, reduced knee flexion (47.7 degrees versus 43.0 degrees , p < 0.05) and ankle plantarflexion (16.8 degrees compared to 3.3 degrees , p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8 degrees compared to 22.0 degrees , p < 0.05) during the swing phase. The plantarflexing ankle joint motion during the stance to swing phase transition (A2) for the young group (31.3 degrees ) was about twice ( p < 0.05) that of the elderly (16.9 degrees ). Reduced knee extension range of motion suggests that the elderly favoured a flexed-knee gait to assist in weight acceptance. Reduced dorsiflexion by the elderly in the swing phase implies greater risk of toe contact with obstacles. Overall, the results suggest that joint angle measures at critical events/phases in the gait cycle provide a useful indication of age-related degeneration in the control of lower limb trajectories during unobstructed walking.

Adaptation, Physiological↗