What characterizes a fixed interval schedule in operant conditioning?

A fixed interval schedule in operant conditioning is characterized by the provision of a reward after a specific time period has elapsed. This means that the reinforcement is given consistently at set intervals, regardless of how many times the desired behavior is performed during that interval. For example, if a worker receives a paycheck every two weeks, this is a fixed interval schedule—after that specific period of time, they receive the reward.

Such schedules are significant because they influence the behavior of the individual by creating a predictable pattern for when to expect reinforcement. This predictability can lead to behaviors being established or increased leading up to the point of reinforcement, often resulting in a "scalloping" effect in which the individual intensifies their behavior as the reinforcement time approaches.