Electroencephalographic alpha, skin conductance and hypnotic capability
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
On the basis of alternative theories it was hypothesized that hypnotisability could be meaningfully enhanced by Antarctic isolation and laboratory controlled sensory deprivation. The research also sought to test Reyher's (1964) psycho physiological theory of brain function in contrast to E.R. Hilgard's (1976, 1977) neo-dissociation interpretation of hypnosis combined with J.R. Hilgard's (1974, 1979) imaginative involvement findings. An additional purpose was to determine the relationship between EEG alpha Density and hypnotisability while controlling for electro dermal arousal. Eight channels of EEG, bipolar skin conductance (SC) and hypnotisability data were collected in Antarctica before and after wintering-over isolation. Ss showed significant increases in hypnotisability and EEG alpha densities following wintering-over isolation. No significant correlation was found between EEG alpha and hypnotisability prior to isolation, but this correlation approached significance following isolation. Correction of EEG records using SC indices of arousal resulted in a significant correlation between EEG alpha and hypnotisability following isolation. In another investigation laboratory controlled sensory deprivation (SD) procedures were used with 10 Ss. The Stanford Hypnotic Clinical Scale (SHCS), a post-hypnotic suggestion for analgesia and pain threshold and tolerance tests were administered prior to SD, immediately after and 10-14 days later. EEG, SC, peripheral, core and chamber temperature data were collected prior to, during and after SD. A control group of 10 Ss was used to assess the effects of repeated hypnosis upon susceptibility scores (plateau effects) and demand characteristics. SD subjects showed significant and dramatic increases in SHCS scores and pain tolerance after SD which was maintained at follow-up testing. These increases were also significant in contrast to control Ss who failed to show significant changes in SHCS or pain measures. The first use of Orne's (1959) post experimental inquiry in such a study did not reveal demand characteristics that might account for results. The maintenance of hypnotisability and pain tolerance at follow-up failed to support Reyher's (1964) theory but was consistent with E. R. Hilgard (1977) and J. R. Hilgard (1974, 1979). Consistent with general EEG-sensory/perceptual deprivation/restriction research and the Antarctic study above EEG alpha densities increased significantly following deprivation, but mid- SD alpha densities were significantly lower than pre- or post- SD levels. Average SD skin conductance levels increased markedly from pre- to mid- SD and then returned to pre- SD levels. The potential of using such psycho physiological measures to determine SD exposure times for maximal hypnotisability enhancement is discussed.