IMPROVEMENT IN VISUAL PERCEPTION FOLLOWING YOGA TRAINING
Shirley Telles, R. Nagarathna and H.R. Nagendra
Vivekananda Kendra Yoga Research Foundation
No.9, Appaiappa Agrahara, Chamarajpet, Bangalore 560 018
Visual discrimination was tested in two groups of 18 College students each, with ages ranging from 17 to 22 years. One group (the
'yoga' group) had 10 days training in yoga. Including asanas (physical postures), pranayama (voluntary regulation of breathing), tratakas (visual focusing exercises), meditation, and lectures on the theory of yoga. The control group carried on with their routine activities. The ability to detect intermittent light of fixed luminance, at varying frequencies was tested in both groups at the beginning and end of 10 days. While Initial values were similar for both groups. at the end of 10 days the frequency at which the yoga group was able to detect the flickering of the stimulus, was significantly more than the initial values (Wilcoxon's paired signed ranks test), whereas the control group showed no significant change. The final value of the yoga group was also significantly more than that of the control group (t test for unpaired data).
Meditation has been described as a training in awareness, which when kept over long periods produces definite changes in perception, attention, and cognition (Brown, 1977). Significant changes were reported in the visual perception of advanced meditators, who were able to distinguish subtle differences in color and shade, and were on the whole more perceptually sensitive (Brown & Engler, 1980). Another study described an increase in visual sensitivity following the practice of the mindfulness Buddhistic meditation (Brown, Forte & Dysart, 1984.) Subjects were able to detect shorter light flashes, and they required a shorter interval to differentiate between successive flashes correctly. In contrast the control group did not change.
It has also been shown that processing of sensory information at the thalamic level is facilitated during the practice of pranayama (Telles et al. 1992), and meditation (Telles & Desiraju, 1993, Telles et al. in press) These two practices, along with physical postures (asanas), cleansing practices (kriyas), devotional sessions, and lectures on the theory and philosophy of yoga were found to bring about an improvement in hand steadiness in college students following 10 days of practice (Telles et al. 1993). This improvement was believed to be due to improved eye-hand co-ordination, attention, concentration, and relaxation, as well. Hence the present study was carried out to assess whether practising the same yogic techniques for 10 days would significantly alter visual perception.