TOEFL Speaking Task 3

The concept of 'behavioral momentum' refers to the tendency of a behavior to persist even when the original reinforcement is removed or weakened. Just as physical momentum keeps an object moving in the absence of an external force, behavioral momentum is built through a history of consistent reinforcement. When a behavior has been consistently rewarded in a particular context, it becomes more resistant to disruption. In psychology, this is often used to explain why some habits are hard to break, even when the rewards for them are no longer present. The key is that past reinforcement creates a kind of 'inertia' for the behavior.

Professor: Let me illustrate this with a study we did with dogs. We trained two groups of dogs to press a lever to get food. For Group A, every time they pressed the lever, they got a treat—100% of the time. For Group B, they only got a treat sometimes—say, 50% of the time. After several weeks, both groups had learned the behavior well. Then we changed the situation: we stopped giving treats entirely, but we also introduced a distraction, like a loud noise. What happened? Group A, the ones who had been reinforced every time, stopped pressing the lever fairly quickly when the treats stopped. But Group B, the ones who had been reinforced only half the time, kept pressing the lever much longer, even with the noise and no treats. Their behavior had greater momentum—it was more resistant to disruption because their reinforcement history was less predictable, which built a stronger habit.