DISCUSSION

The present study showed that after ten days of yoga breathing practices (pranayamas) all four trained groups showed a significant increase in spatial memory scores but not the control group. On the verbal memory scores each of the five groups showed no significant increase but relatively large standard deviations were noted. The percentage increase in scores suggested some differences. Blakeslee (1980) stated that the left hemisphere is more involved with verbal memory, while the right hemisphere is more involved with the recall of non-verbal, spatial information. It appears here that there was no specific lateralized effect of breathing through a particular nostril over the 10 days of pranayama practice by these children. The performance also did not appear to be related to the nostril which was patent at the time of testing.

Several factors could have contributed to the increase in spatial memory scores of the four trained groups. Children were enthusiastic about performing well on tile tests, which they had been told were a way of assessing the benefits they had obtained during the course, but this may have been less applicable for the control group as they received no special treatment. The positive effects of motivation on learning and memory scores increased in the trained groups, while verbal scores did not, makes it unlikely that increased motivation could have contributed only to one set. Also, reduced anxiety can improve the performance on tasks requiring learning and memory (Saltz, 1970) and the anxiety-reducing effects of yoga practice, which are already known (Wallace, Benson, & Wilson, 1971) also could have facilitated this. The lack of higher spatial memory scores for the control group indicates that the increase was not due to familiar material given as a retest.

Although the scores on the verbal and spatial tests were not significantly different, on Day 1 and Day 10 means were significantly different for left and both nostril-breathing groups, so the practice of yoga improved delayed recall scores on the spatial task but not on the verbal task.

The absence of a lateralized effect of selective nostril breathing in the present study could be explained by different factors. Three previous studies reported lateralized effects of uninostril breathing on selective measures of hemisphere functions. The earliest report (Beubel, 1977) described relatively better verbal performance during both naturally occurring right nasal dominance and right forced uninostril breathing by practitioners of Kundalini yoga. In the study by Klein, et.al. (1986) naturally occurring shifts in the nasal patency were reported to be associated with modified performance on verbal or spatial tasks corresponding to the contralateral hemisphere. Both verbal and spatial tasks involved deciding whether stimulus pairs were same or different. For the verbal tasks stimuli were upper and lower case letter pairs, while for the spatial task the stimuli were pairs of random seven dot patterns. Forced unilateral-nostril breathing did not produce a change. In contrast, a subsequent study of undergraduate students whose group average age was 20.7 yr. (Jella & Shannahoff-Khalsa, 1993) showed that forced left- nostril breathing increased spatial performance on a cognitive task. This paper-and-pencil task tested mental rotation, manipulation, and twisting of two and three-dimensional stimulus objects. However, it did not confirm that forced right-nostril breathing increased verbal performance on a task modeled on the Miller- Analogies and SAT tests. Perhaps the difference between the results obtained with normal breathing and with forced uninostril breaching reflects that forced uninostril breathing using a nose plug may be uncomfortable. The present study indicated no lateralized effect following yoga breathing through a specific nostril. Assessments were made on Days 1 (before) and 10 (after) a period of practicing yoga breathing regularly. The 10 days may not have been adequate to produce lateralized changes in these children. Alternatively, the results suggest that the hemisphere-specific effect of selective nostril breathing might be immediate, measurable during or immediately after the selective nostril breathing. The effect was then not observed following regular practice for a specific period as in the present study. Further studies comparing the effect during or immediately after the practice with the effect over a period of time would make this point more clear, as might the application of sophisticated imaging techniques.