Getting to know the right side

The right hemisphere controls actions on the left side of the

body. It’s responsible for spatial skills and recognising faces (see

Chapter 7), as well as other visual processing. The right hemi-

sphere also controls the thinking skills. Damage to this area can

lead to difficulties in reasoning, attention problems, and even poor

memory for visual images.

Researchers have used split brain experiments to understand

more about how the right and left hemispheres work together. As

a treatment for epilepsy, the corpus callosum (the bridge that links

the two hemispheres) is cut. This prevents information from cross-

ing between the two hemispheres.

Here’s how a typical experiment works. A picture of a dog flashes

up on the right side of a computer screen and, therefore, of the

visual field. Because this image is processed by the left hemi-

sphere, which deals with language, the patient is easily able to

recognise the picture and says ‘Dog’. However, if the picture

flashes up on the left side of the computer side (processed by the

right hemisphere), the patient says she can’t see anything! Without

the corpus callosum intact to link information between the two

hemispheres, the right hemisphere of the brain is unable to com-

municate to the left hemisphere what it sees, and therefore the

person can’t translate what she sees into language.