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This research investigated Schmidt's variability-of-practice prediction and the breadth-of-a-movement class. Schmidt's hypothesis was tested by varying the parameters of ball and distance in overarm throwing. Breadth-of-a-movement class was tested by employing two novel tasks not previously used in variability-of-practice designs. 203 kindergarten and first-grade subjects were randomly assigned to one of four conditions, three experimental and one control. Experimental subjects performed 45 trials in their respective training conditions, weight, distance, weight/distance, in one session. Two novel striking tasks were administered to all subjects pre- and posttest to assess the variability-of-practice hypothesis, and the generalizability of overarm throwing and striking. Variability-of-practice in the overarm throw appeared to strengthen the striking schemas of the kindergarten boys. Results suggest some support for the inclusion of throwing and striking in a single-movement class. The concept, breadth of movement class, however, requires further study.

The resulcs of a previous study by the authors ( 2 ) disclosed that there were significant differences between males' and females' expressed concepts of self in performance of selected motor skills. The population in this earlier investigation contained both skilled and non-skilled performers. Scanning the data obtained from this population suggested that the so-called highly skilled performers rated themselves more favorably than did the lesser skilled Ss. Furthermore, these data suggested that a study delimiced to investigation of only highly skilled performers might result in obtaining similar self-racings from females and males in such a group. METHODCriteria were established for classifying Ss as highly skilled as follows: MALES, ( a ) awarded a college varsity letter from a 4-year institution and ( b ) scored at better than the 60th weighted T score on the Larson Motor Abilicy Battery. FEMALES, ( a ) nationally ranked competitors in badminton, swimming, tennis, track and field, softball, or volleyball and ( b ) scored ac becter than the 60th weighted T score on the Scott General Motor Ability Battery.Thirty-six males and 49 females, ranging in age from 18 to 23 yr., who met these crireria were voluntary Ss for this study. All male Ss and 18 female Ss were college students enrolled at the University of California at Los Angeles in the Fall semester, 1961. The remaining females were enrolled concurrently in one of several neighboring four-year institutions. Each S performed a sequence of four motor skills: ( a ) run, ( b ) catch, ( c ) throw, and ( d ) standing broad jump. N o record of his achievement in these performances was made. Upon completion of the sequence each S responded to a Perception Checklist (1 ) . AV (Attitude Valence) scores were obtained for each S on each skill by adding algebraically the number of plus items and the number of minus items selected by S in his response to the checklist. These AV scores represent his self rating for each motor skill performance. AV scores for each skill were then totaled for each group and mean AV scores were computed for the motor skill sequence for males and for females. The r ratio was used to determine whether there were differences between the males and females in their mean self-ratings of their performances of the motor '

No abstract

Four criterion measures were used to assess the vulnerability to change of two variables, stability and object projection, included in a perceptual-motor enhancement program for 60 boys and girls enrolled in a 20-wk., 20-session program, as were 36 male and female controls. Both samples ranged in age from 2 yr., 0 mo. to 5 yr., 8 mo., and all were within the normal range of development. Three beam-walking tests (the beam at different heights and angles) and the overhand throw comprised the criterion measures used for assessment of program effectiveness in stability and object projection. Stability measures were distance divided by time, and object projection scores were determined by velocity of the overhand throw. A three-factor analysis of covariance was utilized to determine significant main effects of age, sex, and treatment. No significant differences were observed. Analysis by age and sex were significantly different on the Inclined Beam test. Analysis by treatment yielded significant differences on the Inclined Beam test and the Overhand Throw. Analysis by age and by sex showed a significant difference in the performance of the Overhand Throw. In summary, performance status of the overhand throw by preschool age children can be improved beyond maturational expectations through guided instruction.