Highly hypnotizable subjects received a nonhypnotic instruction to respond to a particular digit in a display and a posthypnotic suggestion to respond to a different digit. On some test trials, these 2 responses were tested separately; on others, they were placed in conflict. Overall, subjects were no more responsive to posthypnotic cues than to nonhypnotic cues, nor did their response latencies differ. However, response to posthypnotic cues diminished when they conflicted with the nonhypnotic cues. Analysis of response latencies showed that posthypnotic responding interfered with nonhypnotic responding (and vice versa), even on those trials where there was no procedural conflict. Posthypnotic behavior is not inevitably evoked by the presentation of the prearranged cue. Furthermore, the interference between posthypnotic and nonhypnotic responses indicates that posthypnotic responding consumes attentional resources. Both findings indicate that posthypnotic behavior is not automatic in the technical sense of that term.
Int J Clin Exp Hypn. 2010 Oct;58(4):367-82. Tobis IP, Kihlstrom JF. University of Wisconsin, Madison, USA.