Resisting Temptations and the Power of Suggestion

Have you ever struggled to resist a delicious chocolate bar while you were on a diet? Or have you tried to resist drinking the sixth tequila shot which you knew would make you feel miserable the next day? Resisting temptations is difficult. However, a recent study published in Social Cognitive & Affective Neuroscience indicates that there are methods to help you.

Our research team at the Charité hypothesized that hypnotic suggestions and/or autosuggestions (giving suggestions to oneself) may be able to reduce the attractiveness of unhealthy temptations, or more specifically, snack food.
We invited 32 participants who were responsive to hypnosis and assigned them to two groups. One group was hypnotized by a professional hypnotist, while the other group used autosuggestion. Participants in the hypnosis group were suggested to experience disgust whenever they would encounter a color cue after hypnosis, namely green (half of the participants) or blue (the other half). They were further suggested that they would experience disgust only regarding specific snacks, namely either sweet snacks (half of the participants) or salty snacks (the other half). This was done to assess if hypnosis can target specific stimuli, rather than merely inducing a general feeling of disgust. In the autosuggestion group, participants were instructed to make the disgust association (regarding specific snacks and the cue color) on their own, and they were given as much time for this as the hypnotized participants. Afterwards, participants entered a functional magnetic resonance imaging (fMRI) scanner and carried out a virtual auction on sweet and salty snacks (e.g. Mars bars, Snickers bars). These snacks were shown on a background that was blue for half of the time and green for the rest of the time.

Experimental procedure and the paradigm used in the scanner. Source: Ludwig et al, Soc Cogn Affect Neurosci, 2013

We found that participants of both groups were less willing to pay for the snacks targeted by hypnosis or autosuggestion (salty or sweet) when shown on the relevant cue color (blue or green background, depending on the participant). Surprisingly, there were no behavioral differences between the hypnosis and the autosuggestion group. Also, on a self-report questionnaire, participants of both groups indicated that they had indeed experienced disgust regarding the targeted snacks. However, participants subjected to hypnosis described the effects as more automatic, physical, and genuine (not merely simulated) compared to participants who had used autosuggestion. Finally, the fMRI data analysis showed that the ventromedial prefrontal cortex (vmPFC) was activated less when participants (in both groups) made decisions about targeted snacks shown on the cue color compared to the other snacks. The vmPFC is known to correlate with the perceived attractiveness of stimuli. Thus, the fMRI data are consistent with the idea that the targeted snacks were indeed perceived as less attractive than the other types of snacks following the interventions. Interestingly, hypnosis affected vmPFC activation more than autosuggestion.

Effects on VMPFC were stronger in the hypnosis group compared to the autosuggestion group. Source: Ludwig et al, Soc Cogn Affect Neurosci, 2013

In sum, both hypnosis and autosuggestion can decrease the attractiveness of unhealthy snacks. Moreover, neural and self-report evidence indicate that hypnosis has stronger effects than autosuggestion. Future studies should test the longevity of these effects and should determine whether the differences in brain activation and self-report between the groups are relevant for real-life behavior. The next time you want to resist chocolate, take some time to relax and suggest to yourself that it is disgusting - you might be surprised how powerful a suggestion can be.

Reference

Ludwig et al, Soc Cogn Affect Neurosci, 2013

By Dr. rer. nat. Vera Ludwig, Postdoctoral Fellow, Divison of Mind and Brain Research at the Charité.
this article was originally published 2014 in CNS Volume 7, Issue 1, Mind and Brain