The strength of reinforcement or punishment is dependent on schedule and timing. A reinforcer or punisher affects the future frequency of a behavior most strongly if it occurs within seconds of the behavior. A behavior that is reinforced intermittently, at unpredictable intervals, will be more robust and persistent, compared to the ones that are reinforced every time the behavior is performed. For example, if the misbehaving student in the above example was punished a week after the troublesome behavior, that might not affect future behavior.