Final answer:
The airline's frequent flyer program represents a fixed ratio reinforcement schedule since it requires a set number of responses (miles) for a reward (free flight).
Step-by-step explanation:
An airline offering a frequent flyer program where people earn a free flight after accumulating 25,000 miles is an example of a fixed ratio reinforcement schedule. In this type of schedule, a set number of responses (in this case, miles flown) must occur before a behavior is rewarded (receiving a free flight). This is different from variable ratio schedules, where the number of responses needed for a reward varies and can create high and steady response rates due to the unpredictability of the reinforcement.
Comparatively, with a fixed interval reinforcement schedule, behavior is rewarded after a set amount of time, regardless of how many times the behavior is performed within that time. For example, if a patient is allowed a dose of medication every hour, they will only receive it after the hour has passed, which is irrespective of the number of requests made within that hour.