Enhanced incidence of "the sensed presence" in people who have learned to meditate: support for the right hemispheric intrusion hypothesis.

If the "sensed presence" is the transient intrusion of the right hemispheric equivalent of the left hemispheric (and highly linguistic) sense of self, then any process that facilitates interhemispheric electrical coherence should enhance these experiences. As predicted, the "ego-alien intrusion" (sensed presence) factor was specifically and significantly elevated in 221 people who had learned to meditate (65 to 70% were involved in Transcendental Meditation) compared to 860 nonmeditators. Variants of a sensed presence were more frequent in female than in male meditators and were particularly evident in left-handers who had learned to mediate. The effect size suggests that learning a meditation technique is counterindicated for subpopulations, such as borderline, schizotypal, or dissociative personalities, who display very fragile self-concepts.