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Videotapes of the catching action of 28 children aged 4 to 10 years were carefully observed from simultaneous frontal and lateral perspectives. For both one- and two-handed ball catching, three discernible modes of visual attention and limb movement spaced along a maturity continuum were determined. Only for the ten-year-olds catching two-handed did strategies of visual attention (predicting where the ball would be) and limb usage (grasping with the fingers) couple exclusively as in skilled, adult catching. Success in two-handed catching improved exponentially with age from 77% to 96%. For one-handed catching the success rate was 40% at ages 4, 5, and 6 years, 7.5 and 30% at 7 and 8 years, improving steadily to 92% at 10 years. In the middle of age range the drop in performance coincided with the highest incidence of mixed strategies. No gender differences on either strategy or performance were evident.

An eight-year-old boy learned to make one-handed catches by involvement in three 30-min. periods of instruction and practice consisting of modelling, videotape-based performance feedback, and variable practice interspersed with videotaped assessments on seven consecutive days. An adult-like catching action (both hands) emerged in the second session and was used exclusively thereafter. Catching success at the second and third assessments improved from 40% (preferred hand) and 30% (nonpreferred) to over 90% (both hands) on the final assessment. Following the intervention, success and the catching action were similar to those of skillful ten-year-old subjects observed in a previous study.

The purpose of this study was to determine whether movement production during modelling would register timing changes communicated by a model during video-demonstration of a throwing action .60 boys, 12 yr. of age, were placed in three groups and observed a computer-simulated, point-light demonstration of a darts-style movement used by a model to project a lightweight ball about 2.5 m in a forward direction. Only the relative motion of model's wrist, elbow, and shoulder were displayed. First, subjects were required to identify the action. Immediate response was 88% for the fastest demonstration (model's natural cadence with a wrist velocity of 3.5 rad./sec.), 81% (1.45 rad./sec.). and 65% (0.92 rad./sec.). Second, 3 subjects (1 from each of the original groups) modelled the action when the directional change of the model's arm and its spatial arrangement were held constant but the timing of traverse of the arm was randomly varied (3 levels). Analysis showed that all subjects produced the correct sequence of movement. There were no difference in production of the spatial parameters of the demonstrations but significant differences in the modelling of the timing parameters. These findings are related to the use of visual demonstrations during motor skill instruction and, particularly, the communication of specific aspects of an action.

The purpose of this study was to determine whether videotaped demonstrations of an action which displayed only the motion pattern of a model's limb as compared with one which showed both form and motion provide sufficient information for modelling a given pattern of movement. Video-demonstrations of an arm-movement sequence which ended with a throwing action were shown to adult subjects whose task was to model precisely what they saw. Each demonstration lasted 6 sec. and was shown 6 times. It portrayed the arm of a model, who held a small ball, performing a sequence of movements (flexion and extension of the elbow) which ended in the ball being thrown about 2.5 m with a 'darts-style' action. Three types of demonstration were presented: one showed the whole arm in dark clothing against a light-coloured background, another showed the arm as the relative motion of patches of light situated at the shoulder, elbow, and wrist joints, and the third showed the arm as the relative motion of the upper and lower segments of the arm represented by strips of light-reflectant material. These were the stimuli for the between-groups experimental conditions. Goniometry techniques were used to compare the performance of subjects relative to the model. Analysis showed that the order of the preparatory sequence was correctly produced after 4 trials under all conditions. Range of arm movement in projecting the ball closely approximated that of the model after 4 trials in all conditions. The time taken for the arm to project the ball remained constant across trials under all conditions and was always slower than the demonstrated cadence. Differences in timing were significant at [alpha] .06 with movement most like that of the model when the whole arm was observed.