A Variable Ratio Schedule is a type of reinforcement schedule used in behavioral psychology. In this schedule, a response is reinforced after an unpredictable number of responses. This means that the reinforcement occurs at random intervals, making it difficult for the subject to predict when the next reward will come. This schedule is often used in gambling, such as with slot machines, where players receive payouts after an unpredictable number of spins. The uncertainty of when the next reward will occur encourages continued engagement, as individuals are motivated to keep trying in hopes of receiving a payoff.