Since the Great Depression there have been many studies, hypotheses and theories on the subject of human motivation. The first of its kind to be applied to the workforce was Maslow’s Hierarchy of Needs, which is a theory still included in today’s management textbooks. Later theories directly addressed the management-employee relationship--highlighting influential factors that managers can use to understand their subordinates. Motivational forces such as money, environment, cultural values, power and rewards are the focal points of more recent theories.

Hierarchy of Needs

In the late 1930s Abraham Maslow, a psychology professor at Brandeis University, began interviewing his subjects on the basis of their needs. In 1943 he published the Hierarchy of Needs. His works illustrated, in a pyramid formation, the five categories of human needs, from the physiological to self-actualization. Physiological needs are basic food, water and shelter. Once these rudimentary needs are met, individuals aspire to fulfill other needs in hierarchical order: safety, love and relationships, self-esteem, until finally self-actualization. Incidentally, his theory also states that as each level of need is obtained, its value diminishes because the individual is continually striving to get to the next level. Maslow’s theory was the first of its kind to be applied to business, as employees' quests for self-actualization are used in today's managerial practices to motivate them.

Motivation-Hygiene Theory

Frederick Herzberg’s theory discusses the basic conditions humans need in the workplace and juxtaposes them against what they need to perform. Hygiene, as discussed by the psychologist, refers to any factors that relate to the everyday position, such as relationships with superiors and co-workers, salary, work conditions and policies. He states that if the hygiene factors aren’t met, it will lead to job dissatisfaction, not actual motivation. For instance, if an employee isn’t content with the company’s policies, she will not be comfortable at the workplace--which could actually decrease job performance. Increasing employees’ productivity is the result of recognition, responsibility, accountability and growth. If these elements aren’t apparent in the job function, workers will not strive to succeed.

Learned Needs Theory

The Learned Needs Theory is one of the few motivational theories that take into account a worker’s culture. In 1961, David McClelland, a psychological theorist, drafted a theory stating that an individual values one of the three basic needs--power, affiliation and achievement--because of cultural influences. One worker might have the need to control his own environment, thus aspiring to gain power over it. It might be essential for another employee to establish relationships with other project team members, and her need for affiliations is what helps to drive her productivity. Or, the aspiration to be acknowledged or notarized for a work relating to a project could motivate another worker to succeed. Under this theory a manager must assess which of the three motivations govern the individuals he manages, to maximize workers' productivity.

Expectancy Theory

Victor Vroom, a business professor at the Yale School of Management, developed the Expectancy Theory in 1964--which was later amended by the Lyman Porter and Edward Lawler theory in 1968. Vroom theory states that employee motivation is the product of three factors: valence (employee’s desire to achieve the goal), expectancy (employee’s confidence in task completion) and instrumentality (employee’s belief that there will be a reward upon completion). The theory suggests that lack of confidence, desire or reward could lead to a decrease in productivity. Porter and Lawler theory take this theory a step further by categorizing two types of rewards: intrinsic and extrinsic. Intrinsic rewards are the inner satisfaction or sense of accomplishments an employee feels for completing a project, whereas extrinsic rewards are external forms such as the remuneration, prizes or promotion one receives for a job well done--both of which can lead to an increase in productivity.