This study explored the link between personality and hypnosis by focusing on the Tellegen Absorption Questionnaire (or TAS; Tellegen & Atkinson, 1974). The relevance of imagination and attention to this link are reviewed together with studies critical of the assumed association between absorption and hypnotizability. The psychometric properties of the TAS were also reviewed as a possible source of mixed findings reported in the literature.
The procedures used to develop the TAS are criticised and unpublished studies examined which indicate that the TAS has a complex internal factor structure, and not the unifactorial structure previously assumed. Specifically the research programme of this thesis explores the factorial structure of the TAS with more appropriate techniques than used previously and examines the nature of its relationship with hypnosis in the light of its factorial structure.
Four separate but interconnected studies were undertaken, in Study 1 the items comprising the TAS were factor analysed and, the scale found to possess a low level of common variance (at most 25%), and an unclear, but unmistakably complex, factorial structure. At least four latent variables were identified and subscales derived. A single higher order factor was found to be present among the correlations of the oblique rotated primary factors.
Study 2 examined the ability of the four subscales, derived from Study 1, to discriminate between groups of high and low susceptible hypnotic subjects. "Synesthesia" was found to be the most relevant variable in this study. However, highs and lows were poorly discriminated generally. Argument was made that this may have been due to a lack of separation between the contexts of hypnosis and absorption testing.
A modified absorption questionnaire (MODTAS) with a likert scaled (instead of dichotomous) response format was developed and factor analysed in Study 3. MODTAS was found to have a higher level of common variance and clearer factorial structure than the TAS. The scale was found to consist of five correlated primary factors. These were identified as: Altered States of Consciousness, Synesthesia, Imaginative Involvement, Aesthetic Involvement in Nature, and ESP Experiences. A single higher order factor was found to account for the correlations among five previous factors. Study 4 examined the relationship of these five subscales to hypnotic susceptibility. All were significantly related.
However, multiple regression analysis indicated none made significant unique contributions to the prediction of susceptibility. It was concluded that the five variables are related to susceptibility through their relation with the higher order factor, rather than their specific content.
The implications of these findings were discussed with respect to the nature of the link between personality and hypnotic susceptibility. It is argued tentatively that these data support a model where hypnosis, imagination and several other variables can be viewed as expressions of a single underlying human capacity. However, they appear related to this underlying variable as primary factors to a higher order factor and not as the elements of a simple, single ability measure. Imagination and hypnosis are both held by this model to be expressions of a higher order factor but are processes that are not considered to be identical.
Several candidates were considered for the identity of the higher order variable. Imagination is rejected as inadequate to explain all of the manifestations of the higher order factor which were apparent in the previous studies. Flexibility in the ability to selectively shift between different patterns in the deployment of attention is argued to be the most plausible link between the factors of absorption and hypnosis. This variable should be pursued by further research to evaluate the model that has been proposed here.