“You’re tough,” Nick said. “I should have you take a look at some of my grad students.”

“There’s no sense wasting your time. They either have it or they don’t.”

She handed the dog to Nick, who held it awkwardly against his chest while she set up three cinder blocks about ten feet apart. She hid the scent vial inside the center cinder block, then took the puppy back again.

Nick looked down at his chest; there was a large wet spot on his shirt. “This is why I don’t like mammals.”

Alena smiled. “You’re right: Animals do have pretty good instincts.”

Nick shook his head. “Now she gets a sense of humor.”

Alena set the dog down a few feet from the cinder blocks, then reached into her pocket and took out a small, round, mahogany-colored object; she pointed it at the dog like a key fob.

“What’s that?” Nick asked.

“You’ll see.”

They watched while the dog wandered aimlessly around the cinder blocks. After a few minutes it approached an empty block and sniffed at it; Alena did nothing and the dog wandered off again. A few minutes later it approached the center cinder block; the instant its nose neared the concrete, Alena worked her thumb, and the object in her hand made a crickety clicking sound—CLICK clack. She immediately ran to the dog and lavished it with affection.

Nick pointed to the clicker. “May I see that?”

She hesitated, but handed it to him.

Nick adjusted his glasses and looked at it. It was a glossy round buckeye with a thumb-sized slot carved into one side; projecting out of the slot was a thin tab of gunmetal steel. He pushed it with his thumb— CLICK clack. “It’s beautiful,” he said, handing it back.

“My father used to make them.”

“This is classic operant conditioning. You’re using that clicker to reinforce the behavior you’re looking for.”

“That’s right.” She moved the dog away and set it down again. This time it returned to the cinder block in half the time, and Alena once again hit the clicker and showered it with praise.

“He learns fast,” Nick said. “I’ve had freshmen who need a semester to get that far.”

“He’s just imprinting on the cinder block—now we have to tell him what he’s really looking for.” She moved the vial to the first cinder block and released the dog again; it immediately trotted to the same cinder block as before and waited for its reward—but this time there was none. The dog seemed confused. It pawed at the block and stared, but eventually lost interest and wandered away. When it finally approached the block concealing the scent vial—CLICK clack—Alena once again operated the clicker and praised the dog.