ABSTRACT
The human performer is effectively a moving platform (trunk) with manipulative devices (arms and legs) operating with a ‘smart’ processor (the brain and central nervous system). Some 30% of the processor is dedicated to visual information (Hubel 1988). Humans conduct their daily activities in a dynamic, cluttered environment within which survival depends heavily on visually processed information. If vision is disrupted or somehow impaired, even the simplest of tasks becomes laborious. In sport, where participants and objects frequently move on complex and rapid trajectories, the need for efficient vision is paramount. The fact that some sports performers can control a volleyball spiked at speeds approaching 160 kph producing angular velocities greater than 500 degrees per second or, as in baseball, strike a small, hard ball (23 cm in circumference) moving at similar speeds with a round bat (20 cm in circumference), often projecting the object further than 360 metres, is fascinating to both spectators and scientists alike.
