In psychology, a fixed-ratio schedule (FR) is a type of operant conditioning schedule in which a behavior is reinforced after a fixed number of responses. In other words, the reinforcement occurs after a set number of times the behavior is performed.
For example, a rat may receive a food pellet after it presses a lever five times. Once the rat has completed five lever presses, it receives a reward. Another example is an employee who earns a bonus after completing a certain number of tasks or making a certain number of sales.
Fixed-ratio schedules can result in high rates of responding, as the subject becomes motivated to perform the behavior repeatedly in order to receive the reward. However, there is often a pause in responding immediately after the reward is given, followed by a high rate of responding again as the subject works towards the next reinforcement.
Fixed-ratio schedules can also lead to behavioral patterns known as ratio run and post-reinforcement pause. Ratio run refers to the high rate of responding that occurs before the subject reaches the reward threshold, while post-reinforcement pause refers to the pause in responding that occurs immediately after the reward is given.