Suggestions for altered auditory sensitivity, the negative subject effect and hypnotic susceptibility: a signal detection analysis.

Two experiments used signal detection procedures to assess the effects of hypnotic susceptibility, a hypnotic induction procedure, and suggestions for altering auditory acuity on measures of sensitivity and response bias. In Experiment 1, low susceptibles showed higher sensitivity than high susceptibles, and hypnotic induction failed to affect the sensitivity of either highs or lows. Among the high susceptibles, suggestions to either increase or decrease acuity produced increments in sensitivity and reduced individual differences. Thus, suggestions (regardless of the direction of change suggested) probably motivated highs who would have otherwise performed inefficiently to perform as efficiently as the low susceptibles. With respect to response bias, high-susceptible hypnotic subjects given a suggestion for increased acuity behaved in terms of suggested demands; they showed an increased tendency to response "signal." Low-susceptible hypnotic subjects given the same suggestion responded in a counterdemand or "negative subject" fashion; they developed a bias to say "noise." Experiment 2 used a more difficult discrimination task to replicate and extend this counterdemand effect in low susceptibles. Implications for hypnosis research and for research on the negative subject effect are discussed.