Hypnosis and the relationship between trance, suggestion, expectancy and depth.

In the first of two recent papers, Pekala, Kumar, Maurer, Elliot-Carter, Moon and Mullen (2010a) review what they consider to be the relationships between trance or altered state effects, suggestibility, and expectancy, and how they relate to the concepts of hypnosis and hypnotism. They also suggest that these concepts can be assessed with an instrument they term the PCI-HAP (Phenomenology of Consciousness: Inventory-Hypnotic Assessment Procedure). In the second paper (Pekala, Kumar, Elliot-Carter, Moon, & Mullen, 2010b), they set out to determine empirically whether these concepts can predict hypnotic depth scores using the PCI-HAP. They conclude that their results support the view that all of these component processes may be involved in 'hypnotism' and experiences of hypnotic depth. However, according to their conceptualization, 'hypnosis' itself involves, or consists of, only altered state or trance effects. These papers raise a number of fundamental methodological, semantic and conceptual issues that are discussed in this commentary. Topics discussed include distinctions between concepts such as 'hypnosis', and 'hypnotism,' the role of inductions and suggestion in producing hypnotic phenomena, and the measurement and conceptualization of 'hypnotic depth.' It is concluded that many of the problems relating to the definition and conceptualization of terms associated with hypnosis may be clarified by placing the terms in their historical context, and that difficulties in identifying the origins of the experiences and behaviours associated with hypnosis may stem from insufficient attention to the role of suggestion and expectancies in producing hypnotic phenomena, and an over-reliance on the role of the procedures and mechanics of the induction process.

Am J Clin Hypn. 2010 Jul;53(1):47-59. Wagstaff GF. Department of Psychology, University of Liverpool, Eleanor Rathbone Building, Bedford Street South, Liverpool, UK, L69 7ZA.