Delivering reinforcement when the number of responses in a specified period of time is less than or equal to a prescribed limit. this maintains a behavior at a predetermined rate, lower than at its baseline or naturally occurring frequency.
this is a

Differential reinforcement of low rates of behavior

Explanation:

Based on the information provided within the question it can be said that this is a Differential reinforcement of low rates of behavior. Also known as DRL, this requires a minimum amount of time to pass before a reinforcement is introduced, but must be less than the prescribed limit. This technique was created by Ferster and Skinner in 1957.

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