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Biomedical subjects

K M Newell

Publications and source records attributed to K M Newell.

9 recordsLinked to original sources
PubMed1992

Postural stability, tardive dyskinesia and developmental disability.

The postural stability of four adult populations was examined through force platform methods. The four groups were classified as: (1) developmentally disabled (severely and profoundly mentally retarded) with tardive dyskinesia; (2) developmentally disabled but with no history of neuroleptic medication; (3) tardive dyskinetic but of normal intelligence; and (4) a normal and healthy control group. Postural conditions included standing still with arms at side, standing still with one arm or both arms parallel to the ground, and standing still while swinging both arms in the sagittal plane. The findings showed that both tardive dyskinetic and/or developmentally disabled groups exhibited greater sway and variability in centre of pressure motion in contrast to the control group. The developmentally disabled with tardive dyskinesia group also exhibited a strong tendency to produce a different form to the postural sway strategy in that they produced rhythmical centre of pressure motions during stance that were, to some degree, task dependent. The findings show that the combined effects of developmental disability and tardive dyskinesia produce qualitatively and quantitatively different features in postural stability patterns. The data suggest that postural stability measures may be a useful index to assess tardive dyskinesia.

Antipsychotic Agents↗
PubMed1989

Body scale and the development of prehension.

This study examined whether common dimensionless ratios define the critical point in the shifts in the grip coordination pattern of preschoolers and adults engaged in a displacement grasping activity with cubes that varied in object size. The findings indicated that there was an interaction between task constraints and organismic constraints in determining the grasping pattern utilized. However, when the object size is scaled to hand size there are common dimensionless ratios that correspond to the grasping patterns and the limb orientations employed across the age range utilized. Furthermore, 5 grip configurations accounted for the majority of grip variance in both age groups. The findings suggest a strong role for the impact of body scale on the development of coordination and provide preliminary evidence for the view that the development of prehension is a reflection of the constraints imposed on action.

Adolescent↗
PubMed1989

Task constraints and infant grip configurations.

The prehensile grip configurations of infants aged 4 through 8 months were examined as they grasped objects that varied in size and shape. The findings revealed that infants as young as 4 months systematically differentiate grip configurations as a function of the object properties in essentially the same way that 8-month-old infants do. However, the younger 4-month-old infants predominantly used the haptic system in addition to the visual system for information pick-up regarding object properties, whereas 8-month-old infants predominantly used information from the visual system alone to differentiate grip configurations according to the object properties. Infants apparently perceive the same action-relevant information through different emphases of the sensory modes to drive the action system with a similar grip configuration for a given object. It is proposed that the traditional description of an orderly sequence to the development of infant prehension (e.g., Halverson, 1931) is too conservative and inflexible to capture the functionally adaptive prehensile behavior of infants to changing task constraints.

Exploratory Behavior↗
PubMed1979

Coordinating visual and kinaesthetic memory codes.

Four experiments examined the Connolly & Jones (1970) model which postulates that translation between modalities in the cross-modal paradigm occurs before storage in short-term memory. In general, the results provided no support for the translation notion. Delaying until the end of the retention interval knowledge of the reproduction mode failed to produce a matching performance decrement. Subjects were able to maintain the code of original presentation through the retention interval even when they did not expect reproduction to be in this mode. In addition, the asymmetry in the cross-modal matching of visual (V) and kinaesthetic (K) information, whereby K-V performance is more accurate than V-K performance, was found to occur only under certain visual display conditions. The implications of these findings for general models of cross-modal translation were discussed.

Cues↗
PubMed1979

Temporal anticipation of response initiation by mentally retarded persons.

The ability of retarded persons to anticipate a signal to initiate discrete movements of varying complexity was investigated in two experiments. The results revealed an interaction between temporal anticipation and response complexity. Experiment 1 showed no reduction in reaction time (RT) in discrete aiming movements when the foreperiod was changed from a random interval to a fixed interval (1 or 3 seconds). Reaction time did not vary with length of the interval or the difficulty of the movement. Experiment 2 showed a reduction of RT to a simple release response at a fixed 1-second warning interval. The findings reflect the difficulty retarded persons have in programming more complex movements and the interaction of temporal anticipation in this response-initiation process.

Adult↗
PubMed1978

Decision time and movement time as a function of response complexity in retarded persons.

The decision time (reaction time [RT]) and movement time of retarded persons as a function of the amplitude and precision of a discrete movement in both simple and choice RT paradigms was examined. The results showed that RT for retarded persons was considerably longer and more variable than for nonretarded persons. Movement difficulty only elevated RT with both populations in the choice RT paradigm, and the RT regression coefficient for the retarded subjects was considerably greater than that for the the nonretarded group. Retarded subjects' movement time was significantly slower than that of the nonretarded subjects. Movement difficulty elevated movement time for both populations, as defined by Fitts's (1954) law. The slope of the movement-time regression coefficients was significantly higher for retarded persons and did not change across 5 days of practice. These findings suggest that information-processing differences in motor skills between populations can be attributed to response parameters.

Achievement↗