Monday 21 January 2013

The A - Z of Sports Vision - Gaze

The difference between gaze control and eye movements is that gaze control takes into account movements of the head as well as just the eyes. Often, if you’re following an object such as a moving ball, you need to move your head so that you can accurately fixate the point at which you make contact with the ball (by bat, foot, racket etc.) In many sports, the ball moves too fast for the athlete to be able to follow it accurately without moving your head. In fact, the common exhortation to “keep your eyes on the ball” simply isn't possible. In cricket, Land & McLeod (2000) found that elite batsmen actually moved their gaze ahead of the ball, so that they were “lying in wait” for the bounce of the ball on the pitch. This enabled them to make the most appropriate stroke response. Similar strategies were found in table tennis by Ripoll and Fleurance (1988). Players need to be able to track the path of the ball early in its flight so they can predict the bounce point. In tennis, Ripoll & Fleurance found that players visually tracked the ball for on average 150 milliseconds for flat forehands, and 185ms if there was topspin as well. Similarly in cricket, Land & McLeod found that elite batsmen tracked the ball for the first 150 – 200ms of its flight. Just because you’re looking at one place, doesn't necessarily mean that your attention is focused on the same spot. For instance, a boxer who wants to make a body shot can do so without taking his eyes off his opponent’s face. If he had to look down every time, it would give his intention away to his opponent. The fact that he doesn't have to suggests that the two systems – gaze control and attention – are completely separate. However, more recent research has suggested otherwise. Shepard et al (1986) found that it wasn't possible for participants in their studies to change their gaze from one point to another whilst maintaining their visual attention on the initial point. Studies using brain imaging have since discovered that the same nerve pathways within the brain are involved in both moving the gaze and shifting visual attention. So athletes can be looking at one place whilst thinking about somewhere else, but moving the eyes means shifting the attention. It’s also been found by Shepard and others that the shift of attention comes before the shift in gaze. Elite athletes seem to be able to control their attention and gaze on crucial positions at crucial moments in many sports. This is the “Quiet Eye”. But you’ll have to wait until “Q” to find out more about that. David Donner

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