Contrast effect in reinforcement refers to which of the following?

• A. No effect of reward value on behavior
• B. Positive contrast only occurs with food
• C. The quality of behavior is independent of reward magnitude
• D. Change in value of reward will change the quality of behavior

Answer: (D)

Contrast effect in reinforcement is about how changing the value of a reward changes how the dog performs the behavior. When a reward becomes more valuable than before, the dog tends to respond with more vigor, speed, or persistence. If the reward loses value, the same behavior can become weaker or less reliable. The key point is that the amount or quality of reinforcement relative to expectations shifts the quality of the behavior, not just whether a reward is present at all. This effect can involve different kinds of reinforcers, not only food. So the best description is that a change in the value of the reward will change the quality of the behavior.