When children's perceptions are accurate, they can learn from what they see, feel, or hear. On the other hand, if sensory information is faulty or if the input from the various senses fails to merge into a coherent picture, the child's experiences of the world can be confusing. People with autism seem to have one or both of these problems. There may be problems in the sensory signals that reach the brain or in the integration of the sensory signals-and quite possibly, both.
Apparently, as a result of a brain malfunction, many children with autism are highly attuned or even painfully sensitive to certain sounds, textures, tastes, and smells. Some children find the feel of clothes touching their skin so disturbing that they can't focus on anything else. For others, a gentle hug may be overwhelming. Some children cover their ears and scream at the sound of a vacuum cleaner, a distant airplane, a telephone ring, or even the wind. Temple Grandin says, "It was like having a hearing aid that picks up everything, with the volume control stuck on super loud." Because any noise was so painful, she often chose to withdraw and tuned out sounds to the point of seeming deaf.
In autism, the brain also seems unable to balance the senses appropriately. Some children with autism seem oblivious to extreme cold or pain, but react hysterically to things that wouldn't bother other children. A child with autism may break her arm in a fall and never cry. Another child might bash his head on the wall without a wince. On the other hand, a light touch may make the child scream with alarm.
In some people, the senses are even scrambled. One child gags when she feels a certain texture. A man with autism hears a sound when someone touches a point on his chin. Another experiences certain sounds as colors.