Doctor of Philosophy (PhD)



Document Type



Four experiments presented here investigated the task demand relationship of intertrial variability (IV) and regulatory conditions (RC), on the outcome and movement changes that occurred with dart throwing practice. The four tasks included: (1) a stationary target with one location (closed w/no IV), (2) a stationary target with five possible locations (closed w/IV), (3) a moving target with one movement pattern (open w/no IV), (4) a moving target with five possible movement patterns (open w/IV). After each throw, the X, Y coordinates of the dart and the target were recorded to calculate radial error (RE). Kinematics was recorded using an eight-camera motion system with markers on the upper body, throwing arm, and dart. Novice participants performed 160 throws on each of 3 days. Results for all four tasks indicated that the RE decreased significantly (p< 0.05) across trial blocks, at a different magnitude and rate for each task. The displacement patterns of the wrist, elbow, and shoulder indicated changes in movement coordination as novices practiced their respective tasks. During the three days of practice, learners became more consistent in the pattern used. The displacement at the elbow was significantly different from the shoulder and wrist for the two consistent tasks, while the variable tasks revealed the elbow and wrist to be similar. Analysis of the joint-linkage cross-correlations showed the elbow-wrist linkage to be significantly different from the elbow-shoulder and the shoulder-wrist linkages, for all four experiments. These observations suggested that the subject controlled the degrees of freedom at the shoulder, while the elbow and wrist remained linked throughout practice. Closer analysis of the magnitude of the changes indicated an inverse relationship between the movement coordination and outcome changes. Large changes in the movement pattern resulted in small changes in the outcomes and vice versa. The results of these experiments provide evidence that environmental context (EC) affects how one performs, and what changes occur in the outcome scores and movement coordination, but the magnitude of these changes presents differing information regarding skill acquisition. Overall, the results indicated the amount of IV in the EC had the greatest effect on the performance.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Richard A. Magill

Included in

Kinesiology Commons