Jason Mitchell and Mahzarin R. Banaji, of Harvard University, and C. Neil Macrae, at the University of Aberdeen, published a fascinating piece in Neuron in May 2006, ‘Dissociable Medial Prefrontal Contributions to Judgments of Similar and Dissimilar Others’ (abstract on PubMed or pdf download here). I came across the article through the Mind Matters blog in a piece by Stephen Macknik (director of the Laboratory of Behavioral Neurophysiology at the Barrow Neurological Institute in Phoenix), entitled How Harvard students perceive rednecks: The neural basis for prejudice. Both the original article and the blog post by Macknik are worth checking out.

In the experiment, the team headed by Mitchell showed the subjects photographs and asked the subjects questions about the beliefs, feelings, or attitudes of the people in the pictures. Subjects were told the pictures were of either ‘liberal northeastern’ or ‘conservative Midwest fundamentalist Christian students’ after doing a survey which determined which group the subjects were most like. The categories for the photographs were false, the pictures being taken from dating websites and randomly assigned to either of the groups. The photos were reassigned for each subject, and gender, age and other distinguishing marks controlled for (or likely just avoided by the original choice of photos). In other words, college students were being told that other ‘college students’ were either ‘like them’ or ‘different from them,’ with (apparently) no visual cues for either identity. The research team was interested in what parts of the brain were being used in attempts to ‘mentalize,’ that is, to perceive the thoughts, motives or perceptions of others.

In particular, the researchers discussed that slightly different parts of the medial prefrontal cortex (mPFC) are used when trying to mentalize, depending upon whether the target of observation is believed to be similar or dissimilar (should I write ‘the Other’ to prove I’m a cultural anthropologist?) to the self. Specifically, a more ventral (front) part of mPFC is used when ‘mentalizing’ about others perceived as similar, as opposed to a higher (dorsal) part of the mPFC used to deduce the thinking or feelings of others when confronted with photos of people thought to be ‘unlike’ themselves. The difference is significant because the different regions suggest that these perceptions are being accomplished in distinct fashion.

… simulation theories of social cognition suggest that this [ventral] region should be specifically engaged for mental state inferences about others perceived to be similar to oneself, since mentalizing on the basis of self knowledge can only take place if another person’s internal experience is assumed to be comparable to one’s own. As such, this hypothesis suggests an important ‘‘division of labor’’ in the contributions made by different subregions of mPFC to mentalizing. Whereas ventral mPFC may be expected to contribute to mental state inferences about similar others, the dorsal [upper or top] aspects of mPFC—more traditionally associated with mentalizing tasks—should be specifically engaged by mentalizing about dissimilar others, that is, individuals for whom overlap between self and other cannot be assumed.

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