Background and Purpose. The purpose of this study was to investigate the effects of knowledge of performance (KP), either immediate or delayed, on children.
Subjects. Sixteen non-disabled boys, ages nine to eleven participated in this study (X=10.2 years, SD = .83).
Methods. Eight subjects in each of the two KP groups performed a dynamic lifting task. Each subject lifted a weighted box (30% of the child's body weight) from the floor onto a table while attempting to minimize measured disk pressure (L5/S1) and maintain torso angle perpendicular with the horizontal plane. During the acquisition phase KP was provided (1) immediately following completion of the lifting task (Immediate KP) and (2) Eight seconds following the lifting task (Delayed KP). Retention testing immediately following and one week following the acquisition phase were performed without KP. Subjects were videotaped on three separate occasions and later biomechanically analyzed. Separate analyses of variance for repeated measures were used to compare task differences among the two KP groups for preacquisition, immediate retention, and delayed retention trials.
Results. Statistically significant performance and learning effects were found in both immediate and delayed KP groups for disc pressures and torso angles. No significant difference was found for disc pressure or torso angles. No significant difference was found for disc pressure or torso angles between groups.
Conclusions and Discussions. When relatively permanent changes in a dynamic motor task are desired, immediate KP and delayed KP are equivalent in the acquisition of a dynamic motor task. However, relatively temporary changes in the acquisition of a dynamic movement may be enhanced by providing immediate KP rather than delayed KP.
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