Does hypnotic susceptibility influence information processing speed and motor cortical preparatory activity?

Responsiveness to suggestions while hypnotized is termed hypnotic susceptibility. An association between reaction time and hypnotic susceptibility has been demonstrated, but whether distinct changes in brain activity accompany this relationship remains unclear. We investigated the effect of hypnotic susceptibility on the speed of information processing and motor cortical preparatory activity. Twenty-one "low" (Low(HS)) and fifteen "high" (High(HS)) hypnotically susceptible right-handed participants performed precued simple (SRT) and choice (CRT) reaction time key-press tasks under hypnotized and non-hypnotized conditions. Force and surface electromyography data were recorded from left and right index fingers. The contingent negative variation (CNV) was derived from electroencephalography data. Mean reaction time and premotor time was shorter in High(HS) participants than Low(HS) participants for both simple and choice reaction time tasks. High(HS) participants in the hypnotized state performed fewer errors than High(HS) participants in the non-hypnotized state and Low(HS) participants in either state for the SRT task. High(HS) participants made fewer errors overall than Low(HS) participants for the CRT task. Mean C3/C4 CNV amplitude was larger in High(HS) than in Low(HS) participants. Furthermore, larger CNV amplitude was associated with shorter premotor time. Our findings indicate that shorter reaction time in the high hypnotically susceptible group is associated with a greater change in brain activity during motor preparation. One interpretation is that hypnotic susceptibility and neural mechanisms of arousal and selective attention are linked.