More specifically, we combined self-report measures and a cognitive-behavioural task in a population randomly allocated to a yoga or a control group. Self-report measures of mood, stress, and mental health were administered at two time-points, before and after the 10-week course period, and scores provided by participants in the yoga and control groups were compared. We hypothesized that, similar to previous observations in healthy volunteers and patient groups, yoga would be associated with improved mood and psychological wellbeing. Secondly, participants completed a computerized Go/No-Go task after the 10-week yoga period. In this task participants are asked to respond when presented with one cue (in a “Go” trial) but must withhold that response when presented with a second cue (in a “No-Go” trial). By requiring individuals to inhibit pre-potent responses, this task has been used to tap aspects of executive function, and in particular those related to impulsivity (Band and van Boxtel, 1999). There is evidence that deficits in performance are related to difficulties in controlling violent behaviour;