Can Hypnosis Make You Ticklish? Using Suggestion to Modulate Agency

Sense of agency is the subjective sense of control we have over our actions. According to comparator model accounts, this arises when the predicted sensory effects of movements match actual sensory feedback. A consequence of this matching is sensory attenuation of self-generated actions. This explains why, typically, we cannot tickle ourselves. Mechanically manipulating the sensory consequences of actions, however, can create a mismatch and the illusion that they are externally produced; that is, self-tickling becomes ticklish. Across three experiments, we aimed to create similar alterations in agency using hypnosis. We compared different suggestions-based on real-world examples of agency disruptions-for participants of different levels of hypnotizability, with and without a hypnotic induction. We found that suggestions designed to model self-monitoring deficits increased perceived ticklishness. These effects were stronger in high-hypnotizable participants and after an induction. Demand characteristics may explain behavioral but not subjective responses to tickling.