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Fly-ball project

Description : Intercepting Fly Balls

Teams :
- the 'Control and Learning of Finalized Displacements' research team at the Institute of Movement Sciences (ISM), Marseille (France)
- The 'Coordination of Movement' research team at the Centre for Humanmovement Sciences, University of Groningen, the Netherlands

Principal author: Reinoud Boostma

Year : 2007

In the ongoing collaboration between Reinoud Bootsma's group in Marseille and Frank Zaal's group in Groningen, we have studied the way observers know when and how to start running to be able to intercept an approaching fly ball. In the past, we have concentrated on a possible role of optical expansion. The series of experiments performed in Marseilles and in Groningen indicated that the role of optical expansion is only small, as would fit with the hypothesized use of the Chapman strategy, that consistst in zeroing out the optical vertical acceleration of the ball. In the present series of experiments we test this hypothesis more directly. By having participants judge, but also really intercept, approaching virtual fly balls, the pattern of their responses can be held against the pattern expected from the use of the Chapman strategy. Furthermore, the role of the amount of optical texture, potentially affecting the sensitivity of the perceptual system sub-serving the judging of the appropriate diretion of running, will be investigated. The CAVE at Luminy provides a unique platform for these studies, with the L-configuration allowing displacements up to 6 m.