The Brain percives tools as temporary body parts

Researchers have confirmed that when we use a tool, even for just a few minutes, the tool becomes a part of what is known in psychology as our body schema, according to a report published in Current Biology, a Cell Press publication.

"Since the origin of the concept of body schema, the idea of its functional plasticity has always been taken for granted, even if no direct evidence has been provided until now," said Alessandro Farnè of INSERM and the Université Claude Bernard Lyon. "Our series of experiments provides the first, definitive demonstration that this century-old intuition is true."

In the new study the researches reasoned that if one incorporates a used tool into the body schema, his or her subsequent bodily movements should differ when compared to those performed before the tool was used.

Indeed, that is exactly what they observed. After using a mechanical grabber that extended their reach, people behaved as though their arm really was longer, they found.

It's a phenomenon each of us unconsciously experiences every day, the researchers said. The reason you were able to brush your teeth this morning without necessarily looking at your mouth or arm is because your toothbrush was integrated into your brain's representation of your arm.

The findings help to explain how it is that humans use tools so well.

"We believe this ability of our body representation to functionally adapt to incorporate tools is the fundamental basis of skillful tool use," Cardinali said. "Once the tool is incorporated in the body schema, it can be maneuvered and controlled as if it were a body part itself."

Read the full article on Science Blog.

Karen Hopkin of Scientific American reported on this on 60-Second Science, a daily podcast.