Alternatively, a schedule of reinforcement is a pattern of reinforcement delivered to an organism after a specified period of time between receiving the reinforcer. For example, a mouse on a fixed-ratio schedule will receive a piece of cheese every time the mouse performs a trick. Likewise, the roommate will be rewarded with a single choice of an unhealthy meal once a week for each successful week of eating only healthy food. The reward for the roommate is reinforcement; the scheme provides for the opportunity to receive the reward once a week, as well as the specified period of time between receiving the reinforcement; and finally the target behavior is the response. However, when comparing and contrasting the roommate and the mouse, it is important to understand that the roommate's reinforcement pattern is considered a fixed-interval schedule, while the mouse's is a fixed-ratio schedule. This is because there is a finite amount of time between when the roommate can receive the reward, while the mouse can perform so many responses to receive the same amount of responses.