Vision’s touchy-feely side

Tactile input has a greater impact on visual perception than we thought

When vision alone can’t tell you what’s going on in your environment, touch can lend a helping hand. A recent study from Vanderbilt University looked at the way this works by forcing people to feel out a visually ambiguous situation.

Researchers Randolph Blake, Kenith V. Sobel and Thomas W. James created such a scenario by asking subjects to describe the rotation of a virtual sphere with an indeterminate direction of spin while feeling the rotation of a tangible sphere.

The researchers found that when the subjects were touching and seeing at the same time, they tended to see the virtual sphere rotating in the same direction as they felt the real one rotating. But when they touched the real globe first and then saw the virtual one, the rotation of the first didn’t seem affect how they saw the rotation of the second.

In order to get a better idea of where these perceptions come from, the researchers had subjects perform some of the same tasks while monitoring their brain activity using a functional MRI. They found increased activity in a region of the brain that perceives visual motion, but not as much as when the subjects looked at a rotating sphere.

This suggests that touch is linked to the way that we perceive object motion. With our eyes closed, we can’t form a complete perception of a moving environment, but feeling can help to clarify our perceptions of the world around us.