RESULTS There was a significant increase in Critical Flicker Fusion Frequency in the group who received yoga training (P < .005, 't' test for paired data) and a significant reduction in the degree of optical illusion perceived by the same group (p < .005, for In trials and p < .005 for out trials, 't' test for paired data). The control group (without yoga training) showed no significant change. The group mean values of CFF and degree of illusion ("di") for both in and out trails ± SEM of both yoga and control groups on Day 1 and Day 10 are provided in Table1.