Archive for June, 2012

Contagious desires

June 20, 2012

Summary

Have you ever noticed that other people around you influence what you find desirable?  Why are we so susceptible to this kind of social influence?  An article by Lebreton and coworkers identifies brain circuits involved in our tendency to want what other people want.  This tendency and the underlying brain circuits may be important in helping us learn from others during our childhoods.

More details

Have you ever noticed that other people around you influence what you find desirable?   Maybe there is some kind of food, other item, or even person that didn’t seem to be too interesting to you until others started ooo-ing and ahh-ing over them.  Why are we so susceptible to this kind of social influence?  This desire contagion seems to be a deep-seated human tendency, and one that is very adaptive during our early development, because we learn a lot from our parents or caretakers from an early age what is desirable and safe, vs. what should be avoided.  But how does the brain mediate this social contagion of desire?  An article by Lebreton and coworkers (The Journal of Neuroscience, May 23, 2012 issue) addresses this question of what brain circuits are involved in the “mimetic desire phenomenon” or “goal contagion.”  The study recruited healthy, young adult (20-39-year-old) subjects who watched videos of people (but not including the faces of the people) reaching for one of two identical objects of different colors.  This was followed by tasks in which the subjects were asked how much they would like to use or acquire either of the identical objects of different color.  During the tasks, some subjects underwent functional magnetic resonance imaging (fMRI).

As expected, the study found that objects that had been sought by the person in the video were more likely to be desired by the subjects.   According to the authors, the fMRI data indicated that mimetic desire was mediated by an interaction between the “mirror neuron system” (parietal lobe and premotor cortex) and the “brain valuation system,” i.e. the brain reward system (ventral striatum and ventromedial prefrontal cortex).  Based on their analysis, the authors argued the mirror neuron system acted on the brain valuation system.

By design, the videos of people reaching for the objects did not include the people’s faces, because the authors wanted to eliminate a focus on joint attention, i.e. the phenomenon that people tend to look at the same stimuli that others are looking at.  The authors argue that the mimetic desire phenomenon that they are studying is distinct from joint attention because the former (mimetic desire) has to do specifically with desire (positively-valenced motivation), whereas the latter (joint attention) could have to do with any type of attentional/motivational salience, including desire, but also novelty or threat (negatively-valenced motivation).  The authors also argue that the phenomenon they studied is distinct from empathy or emotional resonance, because the subjects could not see the face and hence the emotional state of the person reaching in the videos.  In the study, there was no correlation within the subjects between mimetic desire and empathizing or mentalizing ability as measured by other psychological tests (“empathy questionnaire” and “reading mind in the eyes” tests).

Although the authors carefully distinguish the mimetic desire phenomenon from certain processes affected in autism spectrum disorders (ASD), namely joint attention and empathy, this mimetic desire phenomenon still seems potentially relevant to ASD, because individuals with ASD tend to be less influenced by the desires of others around them.  The authors do note, at the end of their manuscript, that the interaction between the mirror neuron system and the brain valuation system interaction might represent an essential method for social learning in early childhood, before sophisticated language skills have developed.  At the end of the paper, the authors raise the hypothesis that the mirror neuron system might be functionally disconnected from the brain valuation system in individuals with ASD, resulting in their being relatively unaffected by the motivations of others.  But because this study did not involve subjects with ASD, more studies would be needed to test that hypothesis.

Reference:

Lebreton M, Kawa S, Forgeot d’Arc B, Daunizeau J, Pessiglione M (2012) Your goal is mine:  unraveling mimetic desires in the human brain. Journal of Neuroscience 32(21):7146-7157.

©2011-2013 Edward S. Brodkin.  All Rights Reserved

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