Final answer:
In scheduling, an interval refers to the time-based component that dictates when reinforcements are administered in operant conditioning, with fixed interval schedules providing reinforcement at regular times and variable interval schedules doing so unpredictably.
Step-by-step explanation:
An interval in terms of scheduling, particularly within the context of psychology and operant conditioning, refers to the time-based parameter that determines when reinforcements are given in a reinforcement schedule.
Specifically, a fixed interval reinforcement schedule is one where behavior is rewarded after a set amount of time, regardless of how many responses occur within that interval.
Conversely, a variable interval reinforcement schedule rewards behavior after unpredictable amounts of time have passed, thus making the reinforcement seem random to the individual or animal in question.
An example of a fixed interval schedule is a post-surgery patient receiving pain medication at regular hourly intervals. In contrast, the variable interval reinforcement schedule is exemplified by a fast-food restaurant manager who may receive random quality checks, and subsequent rewards, at unpredictable intervals.