Which reinforcement schedule delivers rewards after an unpredictable number of responses?

The correct answer is variable-ratio reinforcement, which is characterized by providing rewards after an unpredictable number of responses. This type of reinforcement schedule creates a situation where the reinforcement (or reward) is delivered after a variable number of behaviors, which means that the exact timing is not fixed. This unpredictability encourages continuous behavior, as the individual knows that a response might eventually result in a reward, but the number required to achieve that reward can vary significantly.

For instance, gambling is a classic example of variable-ratio reinforcement. Players do not know when they will win, which keeps them engaged and playing, as they continue to respond with the hope that their next game will be the one that brings a reward. This leads to a high rate of responding because the reward can come after any number of attempts, creating a strong and persistent behavior pattern.

In contrast, fixed-ratio reinforcement involves rewards after a set number of responses, which can lead to a pause in responding immediately after the reward is given. Fixed-interval reinforcement provides rewards after a specified time period, leading to a pattern of behavior that is more predictable and often less consistent. Variable-interval reinforcement, while also unpredictable, rewards responses after varying time intervals rather than varying amounts of behavior. Thus, variable