Expectancy theory of motivation is given by

Victor Vroom developed the Expectancy Theory of Motivation. While Porter and Lawler later expanded and refined this theory, the original concept was introduced by Vroom.

The theory's foundation lies in understanding that:
1. Expectancy: An individual's belief that effort will result in performance.
2. Instrumentality: The belief that performance will result in rewards or desired outcomes.
3. Valence: The importance or value an individual places on the reward.