Professor Vroom is an authority on the psychological analysis of behavior in organizations, particularly on leadership and decision making. His 1964 book, Work and Motivation, is regarded as landmark in that field.

Expectancy theory was formulated by psychologist Victor Vroom. According to Vroom to motivate someoe mere offering a person something to satisfy his important needs will nt be sufficient. In order for the person to be motivated, he must also be reasonably sure that he has the ability to obtain the reward. An employee's motivation increases when he values a particular outcome highly and when he feels a reasonably good chance of achieving the desired goal. This definition says that : Any individual acts in a way to reach a maximal effect with a minimal effort.

Stated in other words workers motivation wioo be high when they believe that high levels of effort will lead to high performance and high performance will lead to the attainment of desired outcomes. Further according tothe theory a man's motivation is determined by three influencing factors-

1. Expectancy
   As already explained a person’s level of expectancy determines whether he or she believes that a high level of effort will result in a high level of performance. Expectancy is, thus, the belief that efforts are linked to performance

2. Instrumentality
   Instrumentality is a person’s perception about the extent to which performance at a certain level will result in the attainment of outcomes. There should be firm conviction within the employee that high performance will lead to desirable outcomes. Instrumentality is, in short, the belief that performance is related to rewards

3. Valence
   Valence is the importance placed upon the reward. It refers to how desirable each of the out comes available from a job or organization is to a person. This is becase according to the theory people may differ in the preferences for outcomes

High motivation therefore results from high levels of expectancy, instrumentality, and valence. If any one factor is low, motivation will be low. Managers should strive to ensure that employees’ levels of expectancy, instrumentality, and valence are high so that they will be highly motivated.