The contributions from philosophical and physiological sources have generated several stages of evolution in motivational theory since the late 19th century. In the 1800s Descartes’ dualism was often used to distinguish between animal and human motivation. By the end of the 19th century, behavioral theorists such as the American psychologists William James and William McDougall had begun to emphasize the instinctive component of human behaviour and to de-emphasize, and in some cases eliminate from discussion, the more mentalistic concept of will. Other behaviourists, as exemplified by the American psychologist John B. Watson, rejected theories of both instinct and will and emphasized the importance of learning in behaviour. This group conceived behaviour to be a reaction or response (R) to changes in environmental stimulation (S); their S-R psychology subsequently gained popularity, becoming the basis for the school of behaviourism. By the 1920s, the concept of instinct as proposed by theorists such as James and McDougall had been roundly criticized and fell into disrepute. Behaviourism dominated the thinking of motivational theorists and a new motivational concept, drive, congenial to behaviourism’s S-R approach, was born. Drive, initially proposed by the American psychologist Robert S. Woodworth, was developed most fully by Clark Hull, an American psychologist who conceived motivation to result from changed internal bodily needs, which were in turn satisfied by obtaining specific items from the environment. Thus, hunger motivation was thought to occur as a result of a changed internal need for energy that motivated food-seeking behaviour in the environment.

Behaviourism dominated motivational research until the 1960s, but even in the 1920s and ’30s dissenting voices were heard. Researchers such as the American psychologist Edward C. Tolman and the German psychologist Wolfgang Köhler argued for the existence of a more active processing of information in both humans and animals and rejected the mechanistic S-R psychology. These early cognitive psychologists opened the way for other researchers to examine motivation resulting from the expectation of future events, choices among alternatives, and attributions concerning outcomes. In other words, with the advent of cognitive explanations of motivated behaviour, it became possible to argue that behaviours were sometimes purposive. The cognitive approach has proved useful in the analysis of several types of motivation, among them achievement behaviour, dissonance motivation, and self-actualization (see below Cognitive motivation).

Changing perspectives and research on motivation have led away from large, all-encompassing theories of motivation to smaller, discrete theories that explain specific motives or specific aspects of motivation under particular conditions. These microtheories of motivation are conveniently categorized as falling within three major areas: biological, behavioristic, and cognitive explanations.

Genetic contributions

As indicated above, the idea that some motivated behaviours are the result of innate programs manifested in the nervous system had been proposed by James and McDougall in the late 1800s and early 1900s. These early instinct approaches fell into disfavour during the 1920s because of their proponents’ inability to discriminate between instinctive and learned behaviours and because of the realization that labeling an observed behaviour as instinctive did not explain why the behaviour occurred. In Europe, however, a group of biologists interested in the evolutionary significance of animal behaviours kept the concept alive and continued to study the genetic basis of behaviour. Three of these researchers (the Austrians Karl von Frisch and Konrad Lorenz and the Netherlander Nikolaas Tinbergen) were awarded a Nobel Prize in 1973 for their work on the subject. They were early entrants in the field of study known as ethology, which studies the behaviour patterns of animals in their natural habitat. Ethologists argue that the evolutionary significance of a particular behaviour can best be understood after a taxonomy of behaviours for that species has been developed as a result of observation in nature. They propose further that the significance of a behaviour is often clearer when observed in the context of other behaviours of that animal. Ethologists use naturalistic observation and field studies as their most common techniques.

The research conducted by the ethologists showed that some behaviours of some animal species were released in an automatic and mechanical fashion when conditions were appropriate. These behaviours, known as fixed-action patterns, have several salient characteristics: they are specific to the species under study, occur in a highly similar fashion from one occurrence to the next, and do not appear to be appreciably altered by experience. Furthermore, the stimulus that releases these genetically programmed behaviours is usually highly specific, such as a particular colour, shape, or sound. Such stimuli are termed key stimuli or sign stimuli and when provided by a conspecific organism (a member of the same species) are known as social releasers.

One thoroughly researched example of this type of genetically programmed behaviour is the courtship behaviour of the three-spined stickleback, a small fish. During the reproductive season, male sticklebacks become territorial and defend a portion of the streambed against other intruding stickleback males. Ethological analysis of this aggressive behaviour reveals that it is a series of fixed-action patterns released by the reddish coloration of the ventral (under) surface of the intruding males. A female stickleback entering the territory is not attacked because she does not possess the red coloration. Instead she is courted through a complex series of movements termed the zigzag dance. This behaviour pattern performed by the male stickleback is released by the shape of the ventral surface of the female, which is distended as a result of the eggs she carries. (See animal behaviour: Components of behaviour: Movement).

Although the largest number of studies conducted by ethologists has been on nonhuman animals, some ethological researchers have applied the same kinds of analyses to human behaviour. Prominent among these is the Austrian ethologist Irenäus Eibl-Eibesfeldt. In a book entitled Love and Hate: The Natural History of Behavior Patterns, he summarized many years of cross-cultural research on human genetic behaviour patterns. Interestingly, research on the facial expressions associated with emotion has provided some support for the existence of innate motivations in humans.