...who did not differ in frontal EEG asymmetry before training, were randomly assigned to the meditation training (MT; n = 11) or waiting-list (WL; n = 10) group. MT participants were told that nine 30-min sessions of meditation instruction were available to them and were encouraged to attend as many sessions as possible. A standard protocol was used to measure positive and negative affect before and after 15 min of attempted focused-attention meditation according to provided instructions (“relax with your eyes closed, and focus on the flow of your breath at the tip of your nose; if a random thought arises, acknowledge the thought and then simply let it go by gently bringing your attention back to the flow of your breath”).Some results from the paper:
MT and WL participants did not differ in frontal EEG asymmetry before training, paired t(13) = 0.16, r = −.01, p = .88, d = 0.06 (see Figure, click to enlarge). During training, MT participants attended an average of 6.73 (SD = 1.35, range = 4−8) instruction sessions and reported engaging in independent 15-min intervals of meditation an average of 2.24 (SD = 1.01, range = 1−5) times per week. MT participants averaged 6 hr 13 min of training (SD = 1 hr 35 min, range = 3 hr 15 min to 9 hr 8 min) across the 5 weeks. After training, MT participants had significantly greater leftward shift in frontal EEG asymmetry than WL participants did across all time points, paired t(13) = 10.80, r = .40, p less than .001, d = 3.18 (see Figure).
Comparison with the control group (WL) seems somewhat shakey. They were doing nothing except knowing they would be offered training after the first group? What about being given an amount for some other kind of 'instruction' (religious, philosophical, whatever) for the same intervals?
Some clips from the discussion:
With training, focused-attention meditation shifts frontal EEG asymmetry toward a pattern associated with positive, approach-oriented emotions. Further, this shift does not require hundreds or even dozens of hours of practice. Individual MT participants in this study averaged only 5 to 16 min of active training (i.e., instruction, independent practice) per day across 5 weeks, but still exhibited a strong change in EEG asymmetry compared with the WL group. Our results suggest that the benefits of meditation may be more accessible than was previously believed. However, this study does not indicate if such asymmetry is pervasive or is limited to the time of meditation and the brief intervals that immediately surround it...We suggest two explanations for the increase in EEG asymmetry that emerged after so little training. First, our MT participants were able to decide when to practice, and for how long; this flexibility allowed them to determine for themselves when they would be most receptive to meditation, and choosing advantageous times may have heightened the efficacy of the meditation. Second, the small amount of active practice participants reported may have enabled a larger amount of passive practice to occur spontaneously, without a conscious decision to meditate; such passive practice may have strengthened the effects of meditation. This latter explanation is consistent with reports from some MT participants that they occasionally found themselves focusing their attention in the way they had been taught, even without having set out to do so.