FLICKR, TAMBAKO THE JAGUAR
In a famous 1998 psychology experiment, researchers at Princeton placed a rubber hand in front of subjects while having the person hide their real hand behind a screen, then stroked both the real and fake hands with a small paintbrush. The subjects all reported “feeling” brushstrokes on the rubber hand. Their minds had been tricked into registering the prop as a part of their body, an indication, the researchers suggested, of how we sort out what belongs to us and what doesn’t.
A study published this week (October 26) in the Journal of Neuroscience repeated the experiment in mice using rubber tails, the first time this illusion has been tried in animals other than primates. The mice, it turned out, responded just the way humans did. After watching the rubber tail being stroked in synchrony with their actual tail, mice reacted to someone reaching for the fake tail the way they would if it were their own, twisting away in fear.
The finding suggests that non-primate animals might distinguish self from non-self similar to the way humans do, by associating visual cues with tactile ones. The experiment was performed by researchers at the National Rehabilitation Center for Persons with Disabilities in Tokorozawa, Japan.
The perception of body ownership is powerful in humans (we can be tricked into thinking smartphones are part of our body). A better understanding of the process could be helpful for understanding conditions in which that perception goes awry, as is often the case in schizophrenia, Henrik Ehrsson of the Karolinska Institute in Sweden told New Scientist. The discovery that mice experience this phenomenon could pave the way for neurological studies that would not be feasible in humans, he says, potentially offering a more detailed explanation of the illusion.