Which of the following is an example of a fixed interval schedule?

A fixed interval schedule is a type of reinforcement schedule in operant conditioning where a reward is provided after a specified period of time has elapsed, assuming the desired behavior has occurred at least once during that interval. In the context of the question, receiving a paycheck every week exemplifies this concept, as employees are rewarded with their wages at regular, predetermined intervals regardless of their performance in between those pay periods.

This schedule encourages employees to maintain consistent work behavior because they know when to expect their paycheck, reinforcing their efforts to perform their job effectively. The predictability of the weekly paycheck aligns with the definition of a fixed interval schedule, making it a clear example of this type of reinforcement.

In contrast, the other choices involve varying or less predictable forms of reinforcement or are based on performance rather than time intervals. For example, a lottery for attendance or surprising inspections do not adhere to a consistent timing structure, while praising students sporadically does not follow a fixed interval pattern, thus distinguishing those options from a fixed interval schedule.