"B.J., what are you doing?" Polly Surhoff calls from a seat in the shade by their backyard swimming pool. It's not a question. What Polly is really saying is, "B.J., please don't do anything that might require a trip to the emergency room."
The Orioles' elder-statesman outfielder has been standing on the diving board, letting daughters Kendall and Jordan -- ages 10 and 8, respectively -- jump off his shoulders, the ones he uses to make a living by batting and throwing a baseball.
Now he has 12-year-old Mason by the arm, trying to coax him into the water. The kid's stubbornly holding his ground.
"When Mason's mad at you," remarks older brother Austin, 13, who's sitting on the sidelines with his mother, "he'll say, 'You're out of the herd!' "
That's a favorite line from the film Ice Age. Mason loves movies. In the family car, there's a box containing some 60 DVDs that he keeps in a do-not-disturb sequence that nobody has been able to decipher. ("Maybe it's alphabetical according to production company," Polly sighs.)
But this is his Dad's herd, so the two wind up doing a super cannonball, holding hands as they go airborne.
After splashdown, Mason doggie paddles to the shallow end, where something on the lip of the pool catches his eye.
"Oooh, frog!" he exclaims. He scoops it up, eyeballs it, then turns it loose in the chlorinated water.
Unfortunately, it's a baby tree frog, half the size of a thumbnail and sorely in need of a tree right about now.
"We gotta get him out," B.J. tells his son. "He won't live in this water, Mase."
Mason cups the frog in his right palm, scrambles out of the pool and flings it into the grass. Hardly a Nature Channel moment, but the Surhoffs have come to regard these kinds of mundane afternoons as answered prayers, as do the parents of most autistic children.
For years, Mason was adrift in the world, as out of place as a tree frog in a swimming pool. His mother and father had doubts he'd ever talk. He threw ferocious, marathon tantrums they referred to as "tornadoes." Jordan has a scar over one eye where her brother, then about 8, clawed her like a cougar.
These days, however, Polly says of home life, "We never could have expected it to be this good."
Mason can put himself to bed now. He plays with his siblings and surfs the Internet.
And some nights, he'll gaze at a Technicolor sunset painting the horizon beyond their backyard pool and the rolling hills of Baltimore County and he'll gush, "That's heaven!"
The government is about to conduct the most comprehensive study of autism ever undertaken in the United States. Field research could begin in January and encompass some 6,000 case studies.
"There's more that we don't know than we know," says Marshalyn Yeargin-Allsopp, a medical epidemiologist at the federal Centers for Disease Control, which is coordinating the project.
Autism is a developmental disability believed to be largely genetically based. Experts don't have a clear picture of the physiological effects, only that there's a disruption of brain activity.
"There's something going on with how the neurons align themselves," says Rebecca Landa, director of the Center for Autism and Related Disorders at Baltimore's Kennedy Krieger Institute, who is doing her own study on early detection.
As Polly Surhoff puts it, "These kids are wired differently."
How different? Is Mason experiencing what amounts to brain static? Do things around him seem to move too fast or too slow? Does he have a fully developed sense of self?
On the low-functioning end of this so-called "spectrum disorder" is the mute child seemingly lost in a hypnotic trance, mesmerized by his or her own fluttering fingers or a dangling string.
On the high end are those savants made famous by Dustin Hoffman's movie portrayal in Rain Man, the data sponges who memorize the encyclopedia but can't grasp the humor of a knock-knock joke.
Between those two extremes lies a gray zone that the Surhoffs are navigating.
A sign made of jumbo letters cut from brightly colored construction paper hangs over a bookcase in a spacious second-floor room of the house. It reads: "Mason Surhoff's Public Library."
For the past two years, the library's sole member has been home-schooled by Allyson Black, a cheery, 25-year-old tutor who doubles as a sort of big sister extraordinaire.
She and Mason bought the bookcase and arranged the books in precise order according to subject: Comics, Sports, Places, Movies, Dinosaurs, Animals. That last category looms large in Mason's universe.
"How many years till we go to Africa?" Allyson asks.
"Nine," Mason answers. His parents have promised to take him on safari when he turns 21, as he reminds them almost daily.
"What will we see there?" says Allyson.
"Wildebeests and zebras are the mammalian herds."
"Where will we find them?"
"On the Serengeti."
Mason has a near-photographic memory and performs at an advanced level in math and science courses.