Electroencephalographic measurement of possession trance in the field

https://doi.org/10.1016/S1388-2457(02)00002-0Get rights and content

Abstract

Objectives: To verify the utility of a portable electroencephalogram (EEG) measurement system developed for investigating spontaneous EEG from vigorously moving healthy subjects in a possession trance under a natural condition.

Methods: A portable multi-channel EEG telemetry system was developed to record the EEGs of 3 healthy male Balinese while they were performing a ritual dedicatory drama in the field. After reducing extraneous artifacts using a digital filter, the EEGs and their power spectra were analyzed in terms of evolution from one state to another.

Results: During the drama, one of the subjects became possessed while the others did not. The EEG of the possessed subject did not show any pathological findings including epileptic discharges, but indicated enhanced power in the theta and alpha frequency bands during the trance. This finding was not observed in the other two subjects, who did not go into trances, with no pathological EEG findings.

Conclusions: The measurement system and data analysis methods we developed have allowed us, for the first time, to obtain an EEG from healthy subjects who are vigorously moving while in a possession trance. The present technique enables us to use a spontaneous EEG as a marker of the underlying physiology of a state of possession trance.

Introduction

In some traditional cultures, it is widely observed that ordinary, healthy participants in a ritual ceremony enter a state of possession, or a possession trance, without psychoactive drugs. Based on a survey of 488 human societies worldwide, Bourguignon (1973) reported that 90% had institutionalized some form of altered state of consciousness and 57% associated these states with a possession trance. Therefore, it is likely that some biological mechanisms common to all human beings may underlie possession phenomena. Nevertheless, since possession trance has so rarely been investigated from a psychophysiological perspective, such mechanisms are not clear. In the late 1960s, Prince (1968) pointed out that possession states had not been studied physiologically although the unusual behavior and the alterations of consciousness that are associated with possession phenomena suggest an altered state of cerebral physiology. He suggested that future improvements in a portable electroencephalogram (EEG) recording system, including a telemetry system, would make it possible to record physiological data from possessed individuals in the field under natural conditions. Until now, however, no one has yet successfully recorded an EEG under such conditions.

There are at least three major problems facing researchers who wish to make a physiological study, under natural conditions, of a person in a state of possession. First, as Bourguignon and Peitay (1965) have pointed out, the sacred context of most possession phenomena make it extremely difficult to record physiological data in the field. Second, the standard telemetry system does not work in the field because there is no electric power supply and the system lacks portability. In addition, since the equipment is not shockproof, any vigorous movement that a possessed subject makes would easily cause malfunctions during the recording. Third, even if an EEG could be recorded, it would be seriously contaminated by various kinds of artifacts, especially those caused by physical vibratory shocks continuously applied to the electronic circuits of the transmitter during the recording. We have been trying to overcome these difficulties for a long time.

In the present study, we have two aims. The first is to verify the practical utility of the EEG portable recording system that we developed for field use and the reliability of the analysis procedure for a spontaneous EEG excluding the artifacts from body movement. The second is to report the first EEG findings on the subject of possession trances as a pilot study.

We selected Bali Island, Indonesia, as the site for our study based on cultural anthropological studies. Bali is well known as a traditional society where possession trances frequently occur in ordinary healthy people in a ritual ceremony (Covarrubias, 1937, Mead, 1942, Belo, 1960). There are several festal dramas and ritual ceremonies in which participants go into possession trances, but they are performed in a garden deep inside a temple, on grounds that are open only to villagers. Foreigners are rarely allowed in. It is impossible for foreigners to even obtain information about the time and place of such a performance beforehand. We visited Bali several times since 1973 to find a ritual drama or ceremony suitable for our study as well as to establish a relationship of mutual trust with the Balinese people. Due to the sanctity of the rituals and the inviolability of the performance space, it was difficult to persuade performers to put an electric device on their body during a performance, nor could we bring a recording system into the performance space. It took us 11 years to establish mutual trust with the local community and to obtain the consent for our research from executive officers of the temple and religious administrators. We finally received permission to enter a performance space for EEG recordings in 1984.

We had begun the development of a portable multi-channel EEG telemetry system that could be used in the field in the mid-1980s, and continued to test and improve it in the 1990s. With this system, we have been able to identify the temporal and spectral characteristics of extraneous artifacts in the data obtained from vigorously moving subjects, and have developed analysis methods to effectively reduce them.

In this way, we have finally succeeded in recording a multi-channel EEG from a possessed subject in a Balinese ritual ceremony.

Section snippets

Subjects

In Bali, Indonesia, the participants and/or spectators of ritual ceremonies and dramas are known to go into a possession trance without any psychoactive drugs. This phenomenon is called Kerauhan. One of the prominent characteristics of Kerauhan is the fact that it usually occurs not in a professional shaman but in ordinary healthy people en masse during ritual ceremonies. In this study, we focused on a Kerauhan that occurred during a dedicatory ritual drama called ‘Calonarang’. In this drama,

Subjects 1 and 2

Approximately 50 persons participated in the drama. At the beginning, 30–40 players, including Subjects 1 and 2, entered the performance space and started vigorously beating a bamboo musical instrument with a stick. During the drama, they sat at the side of the performance space, continuously playing their instruments. At the climax, about 60 min into the drama, Subject 1 along with a few participants suddenly became possessed. He left his musical instrument and jumped into the center of the

Discussion

We successfully recorded EEGs during possession trances under natural conditions for the first time. This was achieved by establishing a stable relationship of mutual trust with the Balinese people and by developing the necessary recording and analysis systems. The recorded EEG in this study showed an enhancement of the theta and alpha bands of spontaneous EEG activity, and differed from epileptic disorders and mental disorders.

Acknowledgements

We express our special thanks to the Balinese people who accepted us and allowed us to carry out our experiment during their ritual ceremony. We also sincerely thank Ms Sari Sudo and Mr Ida Bagus Sunarta for their continuous support for 20 years in Bali, and the members of the Yamashiro Institute of Science and Culture for their technical support.

References (29)

  • P.M Coons et al.

    EEG studies of two multiple personalities and a control

    Arch Gen Psychiatry

    (1982)
  • M Covarrubias

    Island of Bali

    (1937)
  • D.D Daly

    Epilepsy and syncope

  • M.C Dillbeck et al.

    Short-term longitudinal effects of the transcendental meditation technique on EEG power and coherence

    Int J Neurosci

    (1981)
  • Cited by (0)

    View full text