Motion illusion reveals fixation stability of karate athletes

Abstract

To investigate the effect of smooth pursuit effort against optokinetic nystagmus (OKN) on the magnitude of induced motion, we measured the magnitude of induced motion and eye movements of karate athletes and novices. In Experiment 1, participants were required to pursue a horizontally moving fixation stimulus against a vertically moving inducing stimulus and to point at the most distorted position of the perceived pathway of the fixation stimulus. In Experiments 2 and 3, participants were presented with the inducing stimulus with or without a static fixation stimulus. Experiments 1 and 2 showed a larger magnitude of induced motion and more stable fixation for the athletes than for the novices. Experiment 3 showed no difference in eye movements between the two groups. These results suggest that the magnitude of induced motion reflects fixation stability that may have been strengthened in karate athletes through their experience and training.

These data were previously reported in a somewhat different form at the annual meeting of the Psychonomic Society, Vancouver, November 2002. The research was supported by Grants-in-Aid for Scientific Research 13610095 to S.M and 14101001 to Yoshitaka Nakajima. We thank Kazuo Koga for insightful comments and providing information regarding eye movement recording.