Abstract

The results of recent neurophysiological studies support a strong involvement of frontal lobes in hypnotizability and episodic memory (Crawford et al., 1998; Gruzelier; 1998; Tulving & Lepage, 2000). The present study investigated the relation between individual differences in frontal tasks' performance and episodic memory as well as hypnotizability. In experiment 1, ninety subjects were assessed on a variety of frontal and non-frontal tasks. Frontal lobe processing was measured using a battery of neuropsychological tasks: the Stroop, the Wisconsin Card Sorting Test (WCST), the Target Detection Test (D2), the Trail Making Tests, the FAS Verbal Fluency Test, the Self-Ordered Pointing Test (SOPT) and the Continuous Performance Test. Episodic memory performance was measured using a Remember/Know (R/K) paradigm following the presentation of a study list under full and divided attention conditions. Hypnotizability correlated positively with frontal tests (WCST, Stroop, and SOPT). Highly hypnotizable subjects displayed faster processing across several frontal tasks. Hypnotizability was also related to a higher number of remember responses on a recognition task using the R/K paradigm, and to greater vulnerability to memory distortions in a divided attention condition. Ten High Hypnotizable (HH) and 10 Low Hypnotizable (LH) subjects selected from the same sample were asked to participate in a second experiment. Episodic memories formulated in response to cue-words in and out of hypnosis were rated for cognitive effort and content. Results did not support an effect of increased cognitive effort and response time due to the weakening of the executive system in hypnosis as predicted by the Dissociated-Control Theory of hypnosis (Woody & Bowers, 1994). Low and High hypnotizable subjects formulated equally vivid memories however, HH included more self-reference statements in their episodic memories. The results of both studies suggested that the phenomenological experience of hypnosis is goal-directed and that responsiveness and non-volition may be better explained in terms of experiences of autonoetic consciousness and executive control, rather than the activation of automatic responses resulting from a weakening of executive functions.