“I see a four,” Evan said.

“Good. What color is the number?”

“It’s white.”

“Good.”

More numbers flashed on the screen. Five, three, six, nine. Then letters appeared.

“What do you see now?” the man asked.

“Numbers and letters.”

“What colors are they?”

“They’re all white.”

“All of them?”

“Yes,” Evan said.

The screen faded to black. “You did good, Evan,” the man said. “Now we’re going to try something different.”

The black screen flashed and was suddenly full of spinning gears. The gears were of various sizes and colors, and they spread across the screen in an unbroken chain, each one touching one or two others and all of them moving in unison. The smallest gears moved quickest; the larger ones seemed barely to move at all.

“What do you see?” the man asked.

“I see gears.”

“What are they doing?”

“They’re turning.”

“Good, Evan.”

The gears stopped.

“If the top gear was turning toward the left,” the man at the computer said, “which direction would the bottom gear be turning?”

“Up,” Evan said immediately.

“Which is that, clockwise or counterclockwise?”

“Up,” Evan repeated.

Evan’s mother spoke: “He doesn’t know about clocks, or left or right. I tried to teach him—I mean, we all tried to teach him.…” Her voice trailed off.

The man stepped from his computer and bent to look into the tube at the boy. “If this gear was moving like this,” he said, pointing and turning a circle with his finger, “then which direction would this gear way over here move?”

“Up,” Evan said, pointing along the gear’s outside edge, indicating a clockwise rotation.

The man smiled. “So it would.”

The next series of images were more complex, but Evan’s answers were just as immediate and just as correct. He didn’t have to think about it.