There is a multitude of psychological theories about what motivates man. Is the force inside man, outside man, conditioned or not conditioned, goal directed or not goal directed? These are all very controversial issues in academic research into what gets people to want to work. Most people in organizations are not concerned with academic controversies and rely on their commonsense view of behaviour.
The simplest motivation theory suggests that man is motivated by a series of needs or motives. This theory argues that some of the motives are inherited and some learnt: that some are primarily physiological, while others are primarily psychological. Other theories deny the existence of needs or motives. Therefore, at one extreme the behaviourists argue that behaviour is a series of learned responses to stimuli, and at the other extreme systems theorists talk about all systems - individuals, groups, and organizations - having needs.
Motivation can be either a conscious or an unconscious process: the allocation of time and energy to work in return for rewards. Both internal and external stimuli lead to action. Internalized values, hopes, expectations, and goals affect the decision process of the individual, and thereby affect the resultant behaviour. Motivation is not an 'engine' built inside an individual - as so many training managers believe. It is the individual responding to a whole range of experiences, and responding as a totality, not as 'a need'. If we are threatened by physical force, the stimulus for activity is external. If the hormone secretions in our bodies operate effectively then we will wish to behave in physically satisfying ways. In both examples, some of the force is inside the individual, while some of the stimulus is external. How the individual will respond, how much energy he will expend, and how important are the consequences (rewards) are all factors which moderate his motivation.
There have been many attempts to classify personal moderators in the decision process. The most popular construct is the need, and categories of needs (e.g., body needs, safety needs, social needs, achievement needs) dominate the literature. Goal categories, remarkably like need categories, are also popular (e.g., money, status, power, friendship). Satisfaction theories are a variation of goal theories, but have produced even 14 more controversial classifications (e.g., implicit and explicit rewards).
There is no space here to go into what is primarily an academic debate on theories of behaviour. I will contend that people are motivated to realize the outcome of ends or goals. Where I use the term 'need', I do so in the sense of ends or goals desired by the individual. I have difficulty in accepting a 'need' as a personality construct. However, desiring or wanting an outcome does reveal something about a person, and 'need' can be used to refer to that wanting. To many psychologists this view will be heresy, but I doubt if managers care what the energy force is called (need, want, goal, etc.).
Organizational psychologists adopt hierarchies of goals or needs, along the lines suggested by Maslow, McClelland, Ghiselli, and Likert. Maslow's need classifications are the most extensively used, mainly because they seem to fit organizations rather than because they have been empirically verified. We have little data to support the concept of a hierarchy of needs in which lower order needs are satisfied before higher (hierarchically) order needs. However, while need hierarchies may be difficult to accept, there is a great deal of data on the relevance of these needs or ends or goals for individuals working in organizations, and it is these data which are of value to managers.
The managers' dilemma is that, while they must accept the individual differences that exist among their staff, organizational (and particularly personnel) practices assume that such differences do not exist. The field of organization theory has been - and still is - plagued by the conflict between the individual and the organization. As the orientation of this book is towards organizations, it is important to deal with sameness or similarities between people, while acknowledging differences within groups.
(From Managing people at work by John Hunt)