ASU Research E-Magazine: The Ticking Inside

When someone asks us to count 10 seconds, what is it about our internal clock that prompts us to chant “one thousand one, one thousand two...”? How do comedians know the precise moment to deliver a punch line?

When you say “Good job!” to your dog, how does it know exactly which behavior you’re referring to?

Peter Killeen works full time to answer those and other behavioral questions. An ASU professor of experimental psychology, Killeen uses various mathematical models to understand behaviors such as perception, learning, and motivation.

“It’s the ability to spend long, uninterrupted hours on these questions that permits one to really make radical progress,” Killeen says.

Timing is important in everything from jokes to conversation to lovemaking.

“Some of the world’s greatest tragedies have been the result of bad timing,” Killeen says. When people get excited—whether it’s elation or fear—their internal clocks tick faster.

Killeen studies why people time things the way they do and how their internal timing systems operate. But what about nonverbal organisms—do they gauge time in a manner to humans?

In a representative experiment, Killeen turns on the lights in pigeons’ cages for four seconds and eight seconds. The pigeons have learned how to respond differentially to the time increments by tapping certain buttons. Tapping the correct button provides a food reward.

Reinforcement is a second portion of Killeen’s work. For example, if you praise your dog, how does it know which behavior warranted the praise, so he can repeat it? To scientists, this is the “allocation of credit” problem, Killeen explains.

Learning is best when a trainer’s definition of the good behavior is the same as the trainee’s. Killeen has devised a mathematical way to see how animals define the behavior that is being reinforced. He does this by experimentally varying the requirements for reward until he finds the point at which his and the animal’s definitions of the behavior coincide.

It is at this point, where the experimenter and subject are speaking the same language, that learning is optimal, he says.—Amanda Kingsbury