What reinforcement schedule involves reinforcing a response after an unpredictable number of responses?

The reinforcement schedule that involves reinforcing a response after an unpredictable number of responses is known as a variable-ratio schedule. This means that the reinforcement is delivered after a varying number of responses, which creates a scenario where the subject does not know when the next reinforcement will occur.

This unpredictability encourages a high rate of response, as individuals are motivated to keep responding in anticipation of the next reinforcement. For example, in gambling scenarios, the payoff is often based on a variable-ratio schedule, where one might win after a different number of bets each time. The uncertainty of when the reinforcement (or reward) will occur keeps the individual engaged and responding consistently.

In contrast, the other options refer to different schedules of reinforcement. A fixed-interval schedule would involve reinforcing a response after a specific period, a fixed-ratio schedule would deliver reinforcement after a set number of responses, and a variable-interval schedule would provide reinforcement at unpredictable time intervals rather than based on the number of responses made.