Meditative states based on yoga texts and their effects on performance of a letter-cancellation task.

Performance in a six-letter cancellation task was studied in 35 male experienced meditators with experience ranging from 6 to 12 months. Each participant was studied in four sessions, two Meditation and two Control sessions. The Control sessions were (i) Cancalata or nontargeted thinking and (ii) Ekagrata or focusing on a single topic, in this case, meditation. The Meditation sessions were (i) Dharana or focusing on the symbol "OM" and (ii) Dhyana or an effortless single-thought (of OM) state. Ekagrata and dharana differ in that the former involves focusing with multiple thoughts whereas the latter involves focusing with a single thought, i.e., the significance of OM. The net scores on the six-letter cancellation task were significantly higher after a session of Dharana and lower after the Cancalata session, while there was no significant change after Ekagrata and Dhyana sessions. Focusing on the symbol OM in Dharana may favorably influence selective attention, concentration, visual scanning abilities, and a repetitive motor response compared to other sessions.