Alcohol increases hypnotic susceptibility

One approach to hypnosis suggests that for hypnotic experience to occur frontal lobe activity must be attenuated. For example, cold control theory posits that a lack of awareness of intentions is responsible for the experience of involuntariness and/or the subjective reality of hypnotic suggestions. The mid-dorso-lateral prefrontal cortex and the ACC are candidate regions for such awareness. Alcohol impairs frontal lobe executive function. This study examined whether alcohol affects hypnotisability. We administered 0.8 mg/kg of alcohol or a placebo to 32 medium susceptible participants. They were subsequently hypnotised and given hypnotic suggestions. All participants believed they had received some alcohol. Participants in the alcohol condition were more susceptible to hypnotic suggestions than participants in the placebo condition. Impaired frontal lobe activity facilitates hypnotic responding, which supports theories postulating that attenuation of executive function facilitates hypnotic response, and contradicts theories postulating that hypnotic response involves enhanced inhibitory, attentional or other executive function.     

Goal-directed fantasy, hypnotic susceptibility, and expectancies

We conducted an initial screening session in which hypnosis was presented as a "test of imagination" and administered with other imagination measures. In a second session, we instructed high- and low-hypnotizable subjects to imagine along with suggestions but to resist responding to motoric suggestions. Subjects received either instructions to use goal-directed fantasies (GDFs) or no facilitative instructions. Sizable individual difference effects were secured. Hypnotizable subjects exhibited more suggestion-related movements and reported greater involuntariness than did low-hypnotizable subjects. With GDF instructions, low- and high-hypnotizable subjects reported equivalent GDF absorption and frequencies. However, hypnotizable subjects exhibited greater responsiveness and reported greater involuntariness than did those low in hypnotizability, even when their GDFs were equivalent. Thus, no support was generated for the hypotheses that sustained, elaborated suggestion-related imagery mediates response to suggestion (Arnold, 1946) or that absorption in suggestions is of particular importance for low-hypnotizable subjects (Zamansky & Clark, 1986). Our finding that measures of response expectancy paralelled responding and reports of nonvolition support the hypothesis that expectancies mediate the relation between imagination, involuntariness, and responding (Kirsch, 1985; Spanos, 1982). Hypnotizable imagining subjects in the study discussed here exhibited greater responsiveness than a comparable sample of subjects did in a previous countersuggestion study (Lynn, Nash, Rhue, Frauman, & Stanley, 1983) in which no attempt was made to foster an association between imagining and involuntary responding in the initial screening session.     

Enhancing hypnotic susceptibility: interpersonal and rapport factors

This research supported the hypothesis that hypnosis can be thought of as a set of potentially modifiable social-cognitive skills and attitudes. A low-interpersonal-training treatment devised by Gorassini and Spanos (1986) was compared with a treatment designed to modify not only cognitive factors but also to augment rapport with the trainer and diminish resistance to responding (high-interpersonal training). Fifty percent of the initially unhypnotizable subjects in the high-interpersonal condition tested as being highly susceptible to hypnosis (high susceptibles) at posttest on the Harvard Group Scale of Hypnotic Susceptibility (Shor & Orne, 1962); 25% of the unhypnotizable subjects in the low-interpersonal condition responded comparably. Eighty-three percent of the medium-susceptibility (medium susceptibles) subjects tested as being highly susceptible at posttest in both conditions. Practice-alone control subjects' performance was stable across testings. The study was the first to demonstrate that treatment gains generalize to a battery of novel, demanding suggestions (generalization index) that have been found to differentiate highly susceptible subjects from unhypnotizable simulating subjects. The importance of rapport was evidenced by the finding that rapport ratings paralleled group differences in hypnotic responding and that rapport correlated substantially with susceptibility scores at posttest and with the generalization index. Whereas initial hypnotizability scores correlated significantly with retest susceptibility scores, initial hypnotizability failed to correlate significantly with the generalization index.     

Moderating influences of hypnotic susceptibility on signal-detection task performance

This study investigated the differential influence of hypnotic susceptibility level on signal detection task (SDT) performance in waking and hypnotic conditions. As assessed by the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS: A) and the Stanford Hypnotic Susceptibility Scale, Form C (SHSS: C), 20 high (9–12), 20 medium (4–8), and 20 low (0–3) hypnotizables participated. In counterbalanced conditions of waking and hypnosis, Ss (Subjects) were given 36 signal detection trials, consisting of 12 strong signals, 12 weak signals, and 12 “no” signals. No differences were observed in the waking condition between low, medium, and high hypnotizables on strong and weak signal trials. In hypnosis, high hypnotizables exhibited significantly superior performance on the strong signal trials in comparison with low hypotizables, and performed significantly better on the weak signal trials than did the low and medium hypnotizables. Low and medium hypnotizables performed similarly in waking and hypnotic conditions, while high hypnotizables showed significant enhancements in performance for strong and weak signal trials during hypnosis. This research was supported, in part, by a grant from Fort Hays State University.     

Moderating influences of hypnotic susceptibility on signal-detection task performance

This study investigated the differential influence of hypnotic susceptibility level on signal detection task (SDT) performance in waking and hypnotic conditions. As assessed by the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS: A) and the Stanford Hypnotic Susceptibility Scale, Form C (SHSS: C), 20 high (9–12), 20 medium (4–8), and 20 low (0–3) hypnotizables participated. In counterbalanced conditions of waking and hypnosis, Ss (Subjects) were given 36 signal detection trials, consisting of 12 strong signals, 12 weak signals, and 12 “no” signals. No differences were observed in the waking condition between low, medium, and high hypnotizables on strong and weak signal trials. In hypnosis, high hypnotizables exhibited significantly superior performance on the strong signal trials in comparison with low hypotizables, and performed significantly better on the weak signal trials than did the low and medium hypnotizables. Low and medium hypnotizables performed similarly in waking and hypnotic conditions, while high hypnotizables showed significant enhancements in performance for strong and weak signal trials during hypnosis. This research was supported, in part, by a grant from Fort Hays State University.