Carrots and sticks have long been the favored tool for business managers looking to motivate their workers, whether it’s to encourage with the promise of a raise, or to threaten with firing.

But a recent study from the University of Iowa suggests that an employee’s personality is also a strong motivator of their behavior. Mick Mount and Ning Li, management and organization professors in the Tippie College of Business, note that a growing body of evidence suggests that if a worker’s personality doesn’t fit the job requirements, he or she will not be motivated by external factors—no matter how tasty the carrot or painful the stick.

They’ve used that observation in a newly published paper that lays out a Grand Theory of what makes people tick at the office.

“Our approach shifts the traditional perspective that employee motivational forces are primarily imposed by external situational factors to a view that individual motivation is generated by the pursuit of high-order goals that emanate from one’s personality traits,” they write in their paper, “The Theory of Purposeful Work Behavior,” published in the Academy of Management Review.

Mount and Li reviewed decades of research by behavioral scientists to create their theory that tries to explain why people do what they do at work. The theory can help businesses engage in better hiring and training practices to make sure the right worker is in the right job. By determining why smart people who work hard sometimes fail and sometimes succeed, employers can develop tools that motivate workers to perform more effectively. The theory uses what is called the Five Factor Model (FFM), which captures five broad dimensions of personality that are used to describe human personality: extroversion/introversion, agreeableness, conscientiousness, emotional stability, and openness to experience.

Behavioral scientists for decades have used the FFM to see how people perform at work and interrelate with each other, and it’s proven remarkably effective at explaining human behavior. The Mount and Li theory differs from past research in that it ties FFM personality types to the work environment and the nature of the person’s job. In their integrated theory, workers’ personality traits create high-order goals that they strive to attain in their lives. When the characteristics of their jobs are aligned with their high-order goals, Mount and Li found they tend to be more productive workers.

“Striving to naturally express personality traits leads us to invest more personal resources—mental attention, emotional connections and energetic activity—to fulfill particular types of higher-order goals,” they write. “These implicit goals represent essential, enduring personal agendas that reside at the top of the individual’s goal hierarchy.”

They say that if our job allows us to work towards one of those four higher-order goals—status, autonomy, achievement and communion, or being with other people—then we find a level of psychological fulfillment that intrinsically motivates us to perform our jobs well. If not, then the worker is too bored to care.

So, for instance, if an employee is an ambitious, go-getting extrovert whose high-order goal in life is status, then it will be hard for an employer to motivate the person if he or she works in a repetitive job with no advancement opportunity.

Conversely, if a worker is a shy, retiring type whose goal is autonomy, he or she will not be motivated to perform better by promises of a promotion to management because the last thing he or she wants is to be in charge of other people.

“The implication for businesses, then, is that we first need to understand which goals matter to employees and then match those goals to characteristics of jobs so we can make work more meaningful and intrinsically motivating to the person,” Mount says.

The paper was co-authored with Murray Barrick of Texas A&M University.