METHOD

Subjects

The subjects in the four trained groups were 108 school children whose ages ranged from 10 to 17 years and who were attending a 10-day residential yoga training course during their vacation. There was also a control group of 27 children who were matched with the other four groups on age and who were attending an English medium school. They were similarly assessed before and after 10 days during which they carried on with their routine activities. Hence, performance of this group primarily is pertinent to answering the question of whether an observed effect is merely a retest effect. All subjects were judged right-hand dominant, based on their self-reports as well as actual observation of the hand used by the subject to hold a pen while writing.

Design

The subjects were given the memory test on the first morning of the 10-day camp. The subjects were grouped by age; then subjects of a particu1ar age, e.g., 10 years, were randomly assigned to four training groups (ns = 27). Hence the four groups were of comparable average ages (see below). They had the same routine and learned the same yoga practices, with one difference. Each group was given a different pranayama technique to practice four times a day. The four techniques involved (i) breathing exclusively through the left nostril-chandra anuloma viloma (group's M age was 13.4, SD = 1.4 yr.), (ii) breathing exclusively through the right nostril surya anuloma viloma (group's average age was 14.0, SD = 1.5 yr.), (iii) breathing through both nostrils alternately-nadishudhi pranayama (group's M age was 13.8, SD = 1.2 yr.), or (iv) breath awareness without nostril manipulation (group's M age was 14.6, SD = 1.6 yr.). The fifth control group (group's M age was 13.6, SD=0.9 yr.) of 27 children continued their routine activities for ten days.

Assessment

The subjects were told that the memory tests were for their self-assessment to understand the benefit they derived from the course. They were subsequently given a report, so they were enthusiastic and interested. They were not given further details about the study. The control group were also told that the tests were for their self-assessment and were also given a report. For both verbal the spatial tests a correct response was scored as 1/1 and an incorrect response as a practice trial showed that many subjects got a maximum score (with no scope for further change) when a free-recall test was used, so for the actual assessment a delayed recall test was used as this is known to be more difficult (Russell, 1979). However, there was no special interest in assessing the effect of interference on recall.

On both tests 20 subjects were assessed at a time while seated approximately a meter apart to avoid distraction. The test material was projected on a screen, allowing 10 sec. for each slide. After the 10 slides were shown, a mathematical problem (e.g., 7 minus 4 plus 9 minus 3 plus 6 minus 5 minus 8 plus 2) was projected on the screen: immediately after this, the subjects were asked to recall and write down (or in the case of spatial memory, to draw) within 60 sec. the 10 test items which had been shown to them.

To test verbal memory standard nonsense syllables of three letters, e.g., xol, were selected from a prepared list (Baddeley, 1993). Two different sets of 10 nonsense syllables were presented on Days 1 and 10. The test for spatial memory consisted of 10 simple line drawings. Geometrical or other shapes which could be described verbally, e.g., a square or a circle, were not used. The drawings were very simple and easy to reproduce. As described for verbal memory, there were two separate, similar sets of 10 line drawings each for Days 1 and 10.

Subjects were asked to make a note of which nostril was dominant, i.e., the phase of the nasal cycle, when completed the test. The subjects were asked to test this by occluding the nostrils, one at a time, to cheek which nostril was more congested and which was more easy to breathe through.

Pranayama Practices

The four separate pranayama practices given to each group were practiced as 27 rounds, four times a day (Nagendra, Mohan, & Shriram 1988). The four practices are described below.

(i) The surya anuloma viloma pranayama, or heat-generating breathing practice, involves breathing exclusively through the right nostril while the left nostril is gently occluded. (ii) Chandra anuloma viloma pranayama, or heat dissipating breathing practice, involves breathing through the left nostril whole the right nostril is occluded. (iii) Nadisudhi pranayama or cleansing-breathing practice requires the nostrils to be manipulated with the right hand so that breathing is alternately through left and right nostrils. During practices i, ii, and iii a cross-legged posture is assumed and awareness of the breath is maintained. During the fourth practice, i.e., (iv) Breath awareness, the subject maintained awareness of the breath without manipulation of nostrils.

Analysis

For both verbal and spatial memory tests a correct answer was scored as 1, whereas a wrong answer was scored 0. For each of the five groups separate two-factor analyses of variance were used to test for significance between the verbal and spatial memory test scores, between scores obtained on Days 10 and 1 and for the interaction of tests by days. Data of the 27 subjects in each group were used for analysis, hence there were 27 replicates.

The multiple-comparison Tukey test was used to assess the least significant difference in different comparisons of the groups means for each of the five groups, separately.