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How People Put Themselves Into Other People's Shoes

Do you sometimes identify with the hero while reading a good thriller? How exactly does your brain imagine and appropriate the actions of a fictional character?

This uniquely human ability to adopt someone else's viewpoint is now better understood, thanks to work by Jean Decety's team at Inserm in France, just published in Nature Neuroscience.

The researchers showed that when we imagine ourselves executing an action, the principal brain region that comes into play is the premotor cortex. The same premotor cortex is also activated when we imagine someone else doing the same action, but so are other brain structures such as the parietal cortex in the right hemisphere, which plays a specific role in our ability to distinguish ourselves from others.

This difference in mental processing allows us to understand and (if we approve) to accept other people's intentions.

What goes on when you read a good thriller describing extraordinary events happening to someone who has an otherwise normal existence? Some of these situations are evocative of our own experience, and we often end up identifying with the central character.

In neuropsychological terms, this phenomenon is known as "perspective-taking," and it's essential for social cognition. We can understand other people's motivations because we can imagine ourselves "in their shoes."

This human capacity to adopt someone else's perspective is essential for effective communication. It enables us to understand and (again, if we approve) to accept other people's intentions, desires and beliefs. Almost every day, consciously or subconsciously, we ask ourselves, "What would I do in his/her place?"

Jean Decety and Perrine Ruby wanted to decipher the neurological mechanisms underlying this essential facet of social cognition. Using a positon emission tomograph (PET scanner), they examined which brain regions were stimulated when people were asked to mentally simulate an action from two different subjective perspectives:

* First, when the person imagined doing the action him/herself;

* Second, when the person imagined someone else doing the same action.

For example, in one test, the subjects were presented with familiar objects and were asked to imagine themselves or another person using them.

The PET scan images yielded exciting results: The same brain regions in the frontal cortex (all the premotor regions) were stimulated whether the subjects imagined themselves or someone else performing a given action.

However, the two thought processes also elicited activity in regions specific to the type of simulation. Indeed, the mental representation of a "first person" action specifically involved the so-called somatosensory region of the brain, while the mental representation of the same movement being executed by someone else triggered activity in regions located in the parietal cortex and the frontal lobe of the right hemisphere.

These findings demonstrate the common involvement of some brain regions and the specific involvement of others according to whether we imagine ourselves or someone else performing an action.

On the basis of this new insight, the researchers suggest that, to understand other people's behavior, we create a mental representation of ourselves, and then "project" ourselves into the action we imagine being executed by the other person.

In doing so, the brain maintains the distinction between its "owner" and people exterior to it, through a mechanism that discriminates between self and non-self.

This difference in the way the brain handles its own perspective and that of other people seems crucial to understanding the intentions and actions of other people.

Indeed, the researchers also found that the brain areas involved in self-awareness are impaired in some people with schizophrenia. They are now extending these psychopathological studies to the cerebral origins of cognitive defects such as multiple personality disorder and the abnormal body representations associated with schizophrenia.

(Reference: "Effect of subjective perspective taking during simulation of action: a PET investigation of agency" Perrine Ruby and Jean Decety, Unité Inserm 280, Lyon, France. Nature Neuroscience, May 2001, vol 4, n°5, pp 546 - 550.)

Related website:

Inserm

[Contact: Dr. Jean Decety]

30-Apr-2001

 

 

 

 

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