What type of schedule requires a variable number of responses to obtain a reinforcer?

The correct answer is the variable ratio schedule. In a variable ratio schedule, the reinforcement is delivered after a variable number of responses have been made. This means that the exact number of responses needed to receive reinforcement changes over time, creating unpredictability for the learner. This type of schedule is often associated with high rates of response and strong resistance to extinction, as individuals continue to respond in anticipation of a reward, unaware of when it will come next.

For example, gambling is a classic scenario of a variable ratio schedule; a person might win after an unpredictable number of plays, keeping them engaged as they try to achieve a win.

The other types of schedules mentioned involve different parameters. A fixed ratio schedule provides reinforcement after a specific, set number of responses, which creates a more predictable pattern of reinforcement. A fixed interval schedule offers reinforcement after a specific amount of time has passed, not based on the number of responses. Continuous reinforcement delivers a reward after every single response, therefore not incorporating variability.