Rhythm-induced trance is one of the many documented modes of altered states of consciousness. It has been subject to much scrutiny in research, and often coincides with spirit possession in sacred African dance rituals. Spirit possession, where one experiences spirits controlling his/her mind and body, is a common feature in cultures worldwide. Is the trance state caused by spirit possession, or can it be explained by science?
The context of trance possession varies between different ceremonies and cultures. Steven M. Friedson (1996) describes, in detail, his experience in Malawi with the Tumbuka people, a Bantu speaking group known for their expertise in healing. Their healing rituals are characterized by all-night sessions with continuous drumming and singing. A learned healer is commissioned to facilitate these sessions, and oversees spirit possessions occurring in the group. Friedson describes the ritual as follows:
This kind of spirit-possession trance [in which the conscious will is taken over by the spirit] usually occurs during the treatment phase, when the particular drum modes are sounded. Following homeopathic principles, the drum modes resonate with the particular mode of the vimbuza spirit, heating it past a critical threshold into the world of living. It is during this musical treatment that the vimbuza takes over the personality of the patient and “comes out,” expressing themselves through the vimbuza dance. – Steven Friedson, Dancing Prophets, p. 114
A possession ritual in Liberia, however, looks pretty different. Ceremonies may last only a couple of hours. It is much more based in Christianity, where congregates dress in all white, chant psalms after possession, and claim to be in contact with God. The rhythm on the drum is monotonous, and doesn’t use specific modes as in the Tumbuka ceremony. What this ceremony does have in common with the former is the trance state itself. People convulse, dissociate from themselves, and feel a loss of conscious control.
Some say that trance states are the result of drumming’s effects on the central nervous system. Andrew Neher, a researcher from the 60s, is one of these people. The point is made that multiple frequencies of drums activates multiple neural pathways, similar to light frequencies. Rhythmic light induces similar brain patterns to drumming, where brain waves respond to amplitude and frequency of the stimulus (aka visual/auditory driving). Brain wave frequency is noted to be in between 8 and 13 cycles per second, varying between individuals, but stays constant in the individual himself. Several ceremonies in Africa are noted to have rhythmic frequencies between 7 and 9 cycles per second. The rhythms in these ceremonies are often slowly increased, eventually matching everyone’s individual brain frequencies. The body’s stress increases the release of adrenaline and decreases blood glucose, resulting in the release of adrenochrome, a substance chemically related to hallucinogens.
These trances can also be a result of highly focused attention. Long term potentiation (LTP) is the continuous activation of neural networks that strengthen and reinforce cognitive processes. Different states of consciousness activate different sets of neural networks, or tunings, made possible by LTP. In this interpretation, trance possession is not translated as a reduction in brain activity, but rather as an alternative brain function. This is comparable to REM sleep (dream sleep), where the brain shows patterns of working thought despite an individual being asleep and not fully conscious.
Though we have these theories, scientists are limited in their understanding. One reason is because you can’t really put on an African dance ritual in the lab. Also, there are limits in our knowledge and understanding of the human brain. Though many theories have been put forth, such as the “tuning” of neural networks, they are difficult to test. New theories are coming out often to debunk previous ones and there is no absolute true theory to human brain science.
But maybe the trances are the work of spirits?
Also, I recommend that you blast some funky rhythms with these speakers: