Motivation theories, in its simplest from, are seeking to explain the driving force (s) that convert our thoughts into behaviors. There are numerous theories of motivation, where each are either explaining the same motivational concept with a different verbiage or they are offering a new motivational theory. Regardless, attempting to understand them all would be a very cumbersome task, if not impossible, as there are as many motivational theories as there are scholars that studied and continue to study them. The reality is that understanding motivation is a very complex undertaking because there are many inter-related factors that play within the equation, it isn't a simple cause and effect relationship. If you are interested in reading a Reflection on Motivational Theories.
The categorization of the motivation theories, is an attestation to the complexity of the phenomenon. Therefore, for the purpose of deepening our understanding of motivational concept, we will categorize the Motivational Theories based on "Elsevier's Dictionary of Psychological Theories", where they are divided into three broad categories:
This is the largest category of motivational theories. They are based, like the name suggest, on the role that pleasure plays with regards to organizing our lives. These theories will generally posit that the best way to motivate an individual is from exposing him or her to naturally motivating stimuli. Drive-Arousal or drive-reduction are important concept and both have the potential to lead to optimal motivation.
This category emphasizes the cognitive processes involved within an individual. These theories posit that motivation is the result of active information-processing where an individual, subconsciously or consciously positively evaluates the acting out of a specific behavior, thus is motivated.
This category of motivational theories promotes the concept that motivation is the pursuit of activities that lead to "Growth", "Self-fulfillment", and "Self-Actualization". Among the psychologists, it is generally well accepted that the higher an organism, higher is his level of motivation.