Does habitual, vigorous optokinetic stimulation alter optokinetic nystagmus and sensitivity to circularvection?

Previous studies have shown that experience with optokinetic stimulation can alter a subject's sensitivity to illusions such as circularvection (CV). The aim of the present experiment was to compare optokinetic nystagmus (OKN), optokinetic afternystagmus (OKAN), and sensitivity to CV between 2 groups of sportspeople: 1) squash players (n = 16), who regularly experience vigorous optokinetic stimulation while engaging in their sporting activity, and 2) weightlifters (n = 16), whose sport does not involve the same degree of optokinetic stimulation as squash, but who nevertheless have to achieve a high degree of physical skill. OKN, OKAN (frequency, slow phase velocity, and timeconstant), and latency to CV (Stage 2 and Stage 3) were measured using electro-oculographic recording inside an optokinetic drum. Contrary to predictions, there were no significant differences in OKN, OKAN, or latency to CV between the 2 groups. These results suggest that 1) the practice effects that alter the sensitivity to CV may decay relatively quickly, and 2) differences in recreational sporting activities between subjects may not be a significant confounding factor in visual-vestibular interaction experiments.