"I could touch animals for days," said Callie, "but I will, like, hate human touch a lot."
Callie calls her friend David "Nature Man." He loves horses and fishing.
"With most things, I have a short attention span," David told Pauley. "But with fishing, I can do it for so long, be very patient, and I don't get bored or anything."
" I could probably use some of that," said Christian.
There are more questions than answers about autism. Why, for example, are autism diagnoses increasing so dramatically? In the United States, one of 68 children is diagnosed as "on the spectrum." Among boys, it's one out of 42.
At MIT's McGovern Institute for Brain Research, in Cambridge, Mass., neuroscientist John Gabrieli has made some intriguing discoveries.
"We had teenagers with and without autism in an MRI scanner," said Gabrieli. "And while they were in there, they saw two kinds of faces -- either faces that were looking directly at them, as if they were quite interested in what they were thinking about; or faces whose gaze was averted; they were looking away."
In typical teenagers, there was lots of activity in the back of the brain when they were shown the face that was looking away.
"We think that's a bit of social cognition," said Gabrieli, "trying to think, 'Why is this person not looking at me. They should be looking at me. Is there something dangerous going on there? Do they not like me?'"
But when autistic teenagers look at the same faces, there appears to be almost no activity - no differential sensitivity to social cues.
"In fact, there's almost nothing going on there at all," said Pauley.
"Well, actually, the way we do this kind of research, there could be a lot going on, but we don't know what it is."