Autistic people may have a tangling of the senses

People with autism experience a more extreme version of the world than the rest of us. For more than 90 percent, sounds are louder, colors are brighter, and touch can be a disturbing intrusion. The reason, according to a new study, may be that many autistic people also have synesthesia, a condition of intertwined perception in which one sense stimulates another.

Most people with synesthesia don't find the condition disturbing; many enjoy it. It makes the world a more interesting place.

Synesthetes may see the sound of a symphony as a skein of rippling lines, for example, or a black letter "A" as bright red. People with synesthesia say their experience is not the same as imagination, but they also realize their perceptions are in their own mind and not part of the objects.

"Their experience is somewhere in between, neither imaginary not external, an extra layer in the mind," says cognitive neuroscientist Simon Baron-Cohen of the University of Cambridge, England, who led the study.

Synesthesia has been linked to autism in a few isolated instances. But Baron-Cohen felt that the underlying similarities warranted closer scrutiny. Scientists believe synesthesia is caused by an overabundance of connections between neurons. Curiously, a similar surfeit has been proposed as the cause of autism.

While these interconnections may provide synesthetes with a rich intermingling of sensory experience, people with autism might find the blending of the senses distracting, sometimes to the point where they become withdrawn or soothe themselves with monotonous movements, such as rocking.

People with autism were almost three times as likely to have some type of synesthesia, the researchers report in Molecular Autism. -- ScienceNOW