A person's belief that the effort they put into completing a task will lead to performing at a desired level is called

Expectance

Explanation:

In psychology, the expectancy theory of motivation says that people act in certain ways because they are motivated because of what they expect the result of that behavior will be. This is the reason why people select one behavior over others (because they expect to get better or more desirable results by the one they choose).

Therefore, this theory of motivation doesn't focus on needs but rather on desired outcomes.

This belief that the person has, that the effort they put into completing a task will lead to performing at a desired level is called "expectance" and it basically states that better efforts will result in better performance.