Our Brain Sees the Personal Space of Other People Just Like our Own

Our brains interpret the space near other people just as if this was the space near ourselves, according to research from Karolinska Institutet in Sweden.

The study gives a new approach to a question that psychologists and neuroscientists have long had concerning how the brain represents other people and the events that happens to those people.

“We usually experience others as clearly separated from us, occupying a very different portion of space,” sais lead author Claudio Brozzoli. “However, what this study shows is that we perceive the space around other people in the same way as we perceive the space around our own body.”

The new research showed that visual events taking place near a person’s own hand and those occurring near another’s hand are represented by the same region of the frontal lobe, the premotor cortex.

Shake a Hand if you Can

The brain is able to approximate what happens near another person’s hand, since the neurons that are activated are the same as those that are active when something happens close to our own hand. It is probable that this shared representation of space helps individuals interact, for instance, when shaking hands. It may also help us to intuitively be aware of when other people are at risk of getting hurt, like when we see a friend about to be hit by a car.

In the study, a series of experiments were done in functional magnetic resonance imaging (fMRI). In total, forty-six volunteers took part. In the first experiment, participants looked at a small ball attached to a stick moving first near their own hand, and then near another person’s hand.

The researchers revealed a region in the premotor cortex that contained neuron groups which responded to the object only if it was close to the individual’s own hand, or close to the other person’s hand.

New Neuronal Population Class

In another experiment, these findings were reproduced, before researchers went on, to show that results were not dependent on the order of stimulus presentation near the two hands.

“We know from earlier studies that our brains represent the actions of other people using the same groups of neurons that represent our own actions; the so called mirror neuron system”, explains co-author Henrik Ehrsson. “But here we found a new class of these kinds of neuronal populations that represent space near others just as they represent space near ourselves.”

According to the authors, this study gives a new perspective that could help make possible the understanding of behavioural and emotional interactions between people, since from the brain’s perspective, the space between us is shared.

A shared representation of the space near oneself and others in the human premotor cortex
Claudio Brozzoli, Giovanni Gentile, Loretxu Bergouignan, H. Henrik Ehrsson
Current Biology, 23 September issue, doi: http://dx.doi.org/10.1016/j.cub.2013.07.004