Exquisite visually-guided movements underpin expertise in fast interceptive sports. The assumption that skilled performance relies on superior visual skills has been challenged by studies of sporting expertise which typically advocate vision to be a poor predictor of sporting success. This discordance is addressed in this thesis by examining whether visual degradation (in the form of blur) affects the performance of an interceptive action where successful execution demands precise spatial and temporal visual-motor control. The vision of skilled cricket batters was blurred using contact lenses (four increasing levels: plano, +1.00, +2.00, +3.00) in each of two experimental phases. In the first phase batters faced a bowling-machine and in-situ bowlers to examine the effect of blur on bat-ball interception. The highest level of blur (+3.00) was required to produce a significant decrease in batting performance when facing the bowling-machine at medium-paced ball-velocities (105-115 kph). A similar effect of blur was found when facing in-situ bowlers of comparable ball-velocity, however performance was found to be affected by a lower level of blur (+2.00) for faster-paced ball-velocities (120-130 kph). The +1.00 blur was concluded even at this higher ball-velocity to have no measurable effect on interceptive performance in a natural setting. The second phase sought to investigate the effect of blur on anticipation: a perceptual skill established to be an important component of expertise in many interceptive sports. It was established, using temporal occlusion of a bowling sequence, that optimal anticipation required an opportunity for bat-ball interception (facilitating close coupling between perception and action). Coupled anticipation demonstrated velocity-dependent resilience to blur; +3.00 and +2.00 were required for respective decreases in the anticipation of action-sequences for medium- and fast-paced ball-velocities. Remarkably, results suggest that blur may enhance uncoupled (verbal) anticipation according to the movement velocity of the bowler. Experimental results led to the conclusion that clear vision is not necessarily required for optimal interceptive performance, even when the demanding spatio-temporal task simulates the conditions experienced at the highest levels of competition. Results are interpreted based on the predictions of the dual-pathway theory of vision, including differences in the underlying visual information processed via these pathways.
| Identifer | oai:union.ndltd.org:ADTP/272657 |
| Date | January 2010 |
| Creators | Mann, David Lindsay, Optometry & Vision Science, Faculty of Science, UNSW |
| Publisher | Awarded By:University of New South Wales. Optometry & Vision Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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