First developed by Yale School of Management professor Victor Vroom in 1964, the expectancy theory of motivation attempts to explain what keeps employees working. Its underlying principle is that employees perform in work situations because they expect to receive a direct reward, a factor called expectancy. Their performance is tied to both the degree to which they think they'll be rewarded, which is a factor called instrumentality, and the degree to which they want the reward, which is called valance. Understanding this theory is key in small businesses, many of which frequently run lean and, as such, could greatly benefit from having a well-motivated and highly productive workforce.

Multiplicative or Additive

The model underlying the expectancy theory states that Motivation is equal to Expectancy multiplied by Instrumentality multiplied by Valance. Under the theory, if any of the factors are zero, the employee will be unmotivated. However, in the real world, employees work hard at times even if they're not sure they'll get the reward they hope for. As such, research included in the "Oxford Handbook of Motivation" implies that the equation should be additive: Motivation equals Expectancy plus Instrumentality plus Valance.

Lack of Values

One of the expectancy theory's greatest strengths is also one of its greatest weaknesses. The theory is inherently rational, assuming that employees always act purely out of self-interest and their desire for reward. However, the theory also omits the possibility that an employee may be motivated by other factors. Many employees are motivated to do the right thing or to be team players, regardless of the reward. Because the theory doesn't account for this, it can lead to an employer missing out on an excellent motivational tool.

Timing Issues

The expectancy theory looks at every motivational factor as a stand-alone event. Under the theory's worldview, employees work on a project for a certain reward, then go on to the next one for the next reward. It, however, doesn't take into account an employee who does the right thing on a project or two because of a desire to get promoted to meet her long-term career plan. That employee is motivated by a reward, but she's not motivated by a reward tied to a project. This makes the expectancy theory weak at predicting long-term patterns of behavior.

Implementation Challenges

Employees usually don't walk into their managers' offices with neatly typed lists of the rewards they want, sorted in order of how bad they want them. However, the expectancy theory assumes that managers have access to employee instrumentality and valance factors. Without knowing exactly what employees want and how bad they want it, it becomes very hard to anticipate how motivated they will be to take on a task, even if a reward is offered. Sales contests are a microcosm of this. Invariably, the prize gets a few producers excited while the rest tune the contest out and achieve limited, if any, productivity gains. This happens because, in the real world, managers don't always know how to motivate each member of their teams.

The Real Problem

Ultimately, expectancy theory has a core problem: instead of describing the complexities of employee motivation, it uses complex language to describe a simplistic view of why employees try. In plain English, it says that employees work hard to get something in return. However, it misses the rest of the story, which is that employees work hard to get something in return, but that something might come down the line in a way that's unrelated to the project on which they worked hard in the first place.