Tools Are Body Parts to Brain
In a report in the journal Current Biology, researchers claim that the brain interprets a tool, such as a hammer, as a temporary extension of your physical body. Karen Hopkin reports

[The following is an exact transcript of this podcast.]

If all you have is a hammer, they say that everything looks like a nail. But when you use that hammer, it looks like your arm—to your brain, anyway. A report in the June 23rd issue of the journal Current Biology shows that the brain interprets tools as just an extension of your physical self.

To move our bodies around in space, the brain builds what’s called a “body schema,” a representation of all our various parts. And this so-called schema is frequently updated to keep up with our ever-changing bodies. Otherwise, you’d think you were still a bitty baby. Now scientists have taken this body-image overhaul a step further. They’ve shown that when we use a tool, even for a few minutes, the brain sees it as a temporary body part.

Subjects were asked to pick up a block. They then used a long, mechanical grabber to pick up the same block. Then they tried to snag the block barehanded again. And it took longer than their initial grab. That’s because they were briefly behaving like their arms were still augmented. So next time you feel like a total tool, you might just be hitting the nail on the head.

—Karen Hopkin