When it comes to disorders of the mind, our society has a tendency to seek out the safety of clear-cut categories. We want there to be a bright line separating normal from abnormal, health from sickness.

Alas, the human brain is a category buster, an organ so complicated that it continues to surprise and confound.

Consider autism. In recent years, autism has received an increasing amount of attention, largely because of a dramatic increase in its incidence. According to a new report from the Centers for Disease Control, about 1 in 88 children is now diagnosed with autism-spectrum disorders, which include "classic" autism as well as Asperger syndrome.

These diagnoses are often based on observed deficits in social interaction, such as a lack of eye contact or verbal conversation. Temple Grandin, a noted autistic doctor, describes the experience of spending time with nonautistics as akin to being "an anthropologist on Mars."

Because of these obvious shortcomings