Varieties of attention in hypnosis and meditation.

In their commentary, Oakley and Halligan (2011) echo their recent thoughts regarding the cognitive neuroscience of hypnosis and suggestion (Oakley & Halligan, 2009, 2010). Here we address some of the issues they raise concerning the quest for neuropsychological markers of hypnotic states, the use of hypnotic vs. posthypnotic suggestions, and the potential for other forms of atypical attention such as meditative practices to elucidate hypnosis and de-automatization. Oakley and Halligan twice allude to the paucity of data indicating a special neuropsychological ‘‘state’’ of hypnosis sometimes known as ‘‘trance’’ (2011). The authors note, however, that recent investigations show some promise of identifying a neural marker of hypnosis. Whereas some evidence, including our own research, supports the idea that hypnotic phenomena typically follow suggestions even in the absence of a formal induction procedure (Mazzoni et al., 2009; McGeown et al., 2012; Raz, Kirsch, Pollard, & Nitkin-Kaner, 2006), other research findings may serve to support a distinctive physiological marker unique to hypnosis or to hypnotic suggestions (e.g., Cojan et al., 2009; Demertzi et al., 2011; Pyka et al., 2011; Raz, Fan, & Posner, 2005; Terhune, Cardeña, & Lindgren, 2010; Vanhaudenhuyse et al., 2009). Scholars, however, hardly agree even about the behavioral and phenomenological characteristics that typify ostensible hypnotic planes. For example, distinct sub-types of highly hypnotically suggestible individuals seem to diverge in their experience and behavior throughout hypnosis, challenging the view of hypnosis as a unitary concept (Terhune, Cardeña, & Lindgren, 2011). In addition, the literature provides mixed accounts of how psychological factors such as context, sense of control, relaxation, and expectation relate to hypnosis (Kihlstrom, 2008). An adequate psychological model, therefore, would be instrumental to understanding hypnosis from a physiological perspective. In research settings, as in clinical practice, specific suggestions often accompany hypnosis. Few reports, however, have investigated brain and behavioral correlates of ‘‘neutral’’ hypnosis sans post-induction suggestions (Cardeña, 2005; Cardeña, Jönsson, Terhune, & Marcusson-Clavertz, 2012; Kihlstrom & Edmonston, 1971; McGeown, Mazzoni, Venneri, & Kirsch, 2009). These few published accounts, moreover, rarely control for the effects of implicit suggestions—for relaxation, drowsiness, and focused attention—that are ubiquitous in classic hypnotic inductions. In addition, it appears that the influence of neutral hypnosis is different from that of hypnosis with explicit suggestions. For example, in response to incongruent Stroop stimuli, highly hypnotically suggestible individuals demonstrated increased conflict-related brain activity in the anterior cingulate cortex (ACC) following neutral induction (Egner, Jamieson, & Gruzelier, 2005); conversely, when offered an explicit suggestion to perceive the stimuli as meaningless symbols, participants showed decreased fMRI signal in the ACC (Raz et al., 2005). Further research, therefore, would need to carefully tease apart such hypnotic variations. Whether or not hypnosis involves distinct neurocognitive indices, posthypnotic suggestion (PHS) provides a useful experimental alternative to hypnotic suggestion. PHS refers to a condition during common wakefulness following termination of the hypnotic experience, wherein a subject is compliant with a suggestion made during the hypnotic episode. Thus, PHS keeps cognitive performance untarnished by potential confounding factors associated with the ritual of hypnosis. Oakley