Andrew works for NASA and gets paid once a month, where as his friend George works at a fast food restaurant and gets paid once a week. Despite the difference in when they are paid, both are paid on a schedule of reinforcement.

Fixed-interval

Explanation: fixed-interval schedule is a schedule of reinforcement where the first response is rewarded only after a specified amount of time has elapsed. Despite the difference in when Andrew and George gets paid, both are paid on a fixed interval schedule. I.e each of them have a specified period of time they receive their reinforcement. A fixed interval reinforcement schedule is when behavior is rewarded after a set amount of time.

its d i know cause i've been googling it