The suggestible brain: posthypnotic effects on value-based decision-making

Abstract

Hypnosis can affect perception, motor function and memory. However, so far no study using neuroimaging has investigated whether hypnosis can influence reward processing and decision-making. Here, we assessed whether posthypnotic suggestions can diminish the attractiveness of unhealthy food and whether this is more effective than diminishing attractiveness by one's own effort via autosuggestion. In total, 16 participants were hypnotized and 16 others were instructed to associate a color cue (blue or green) with disgust regarding specific snacks (sweet or salty). Afterwards, participants bid for snack items shown on an either blue or green background during functional magnetic resonance imaging measurement. Both hypnosis and autosuggestion successfully devalued snacks. This was indicated by participants' decision-making, their self-report and by decreased blood oxygen level-dependent signal in the ventromedial prefrontal cortex (vmPFC), a region known to represent value. Different vmPFC subregions coded for cue and snack type. The cue had significantly stronger effects on vmPFC after hypnosis than after autosuggestion, indicating that hypnosis was more effective in genuinely reducing value. Supporting previous findings, the precuneus was involved in the hypnotic effects by encoding whether a snack was sweet or salty during hypnotic cue presentation. Our results demonstrate that posthypnotic suggestions can influence valuation and decision-making.

The role of frontal executive functions in hypnosis and hypnotic suggestibility.

“…Similarly, Ludwig et al (2014) have shown reduced activation in reward-related frontal regions (ventromedial PFC) following a post-hypnotic suggestion to diminish the attractiveness of unhealthy food. In both these cases the reduced neural activity in the frontal regions was directly related to the task (ACC for conflict, and vmPFC for reward) and no post-hypnotic activations/deactivations were established.…”

Hypnosis and top-down regulation of consciousness

“…For instance, only preliminary research has used suggestion to induce agnosia (Weitzenhoffer & Hilgard, 1967), visuospatial processing (Priftis et al, 2011), or changes in affect (Wheatley & Haidt, 2005) or decision making (Ludwig et al, 2013). More broadly, although it is unlikely that suggestion will effectively modulate low-level biological functions, relatively little is known about the psychological limits of hypnotic suggestion, namely which psychological functions are impervious to the influence of suggestion.…”

What’s in a word? How instructions, suggestions, and social information change pain and emotion

“…One recent study tested the effects of hypnotic suggestion on disgust for different salty and sweet snacks (Ludwig et al, 2014). The results showed a significant modulation of snack preferences based on hypnotic, and to a slightly smaller extent, non-hypnotic suggestion.…”