Schedules of Reinforcement

Description of the Strategy

The rate at which learning occurs varies according to the consequences that follow a behavior, and such consequences can occur on various “schedules.” Consequences that follow a behavior and strengthen the likelihood that the behavior will be performed again in the future are referred to as reinforcers. Reinforcers, ideally, are delivered following an appropriate, or desirable, behavior, and the frequency and conditions by which they occur will yield changes in the behaviors performed by a child. Indeed, much of the variability observed in children's behavior can be explained by differences in schedules of reinforcement.

Schedules of reinforcement can be defined according to two basic parameters: (1) ratio versus interval and (2) fixed versus variable. Ratio schedules provide reinforcement based on a number of behaviors, whereas interval schedules deliver reinforcement following behavior that occurs after the passage of a given interval of time. With fixed schedules, reinforcers are delivered after an exact number of responses or an exact interval of time, whereas with variable schedules, the rate at which reinforcement is delivered occurs according to an average number of responses or average intervals of time.

If the two parameters of ratio versus interval and fixed versus variable are crossed, almost any schedule of reinforcement can be classified into one of the four types: fixed ratio, variable ratio, fixed interval, or variable interval.

Under fixed ratio (FR) schedules of reinforcement, a reinforcer is delivered when a target response has been emitted a specified number of times. FR schedules require that reinforcers are delivered consistently following the same number of responses, and that the counting of responses required for the delivery of a reinforcer begins after the previous reinforcer has been provided. Under FR schedules, the time interval between reinforcers will necessarily vary, as the interval depends on the number of responses displayed.

A special case of the FR schedule is that in which the ratio of responses to reinforcers is 1:1. Specifically, an FR 1 schedule (“1” meaning delivery of a reinforcer after one response) is called a “continuous” schedule of reinforcement. Schedules requiring more than one response for a reinforcer are called “intermittent” schedules. Although continuous schedules will yield a higher rate of new response acquisition, intermittent schedules are typically more effective in producing a stable or consistent pattern of behavioral responding. In the natural environment, FR schedules are relatively rare, as reinforcers are not typically delivered in a consistent manner after exactly the same number of responses has been emitted. One example of an FR schedule is household chores, for which the child is provided with a reinforcer upon the completion of a set number of tasks.

Under a variable ratio (VR) schedule of reinforcement, the number of responses that the child must emit before a reinforcer is delivered varies around a set number. For example, on a VR 50 schedule, a reinforcer would be delivered after an average of 50 responses but would not always be delivered after precisely 50 responses.

VR schedules occur fairly commonly, such that in many circumstances it is difficult to predict when one's efforts will lead to a reinforcer. When rewards are unpredictable, the child must continue to exert effort at a steady rate. VR schedules are often observed in the social interactions of children, such that when children attempt to initiate play with their peers, some overtures will be reinforced by acceptance, whereas other invitations will be declined. Another example of a VR schedule is free throws with a basketball, such that the child must make a variable number of shots before one goes in.

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