From the 1950s, marketing began to shift is reliance away from economics and towards other disciplines, notably the behavioural sciences, including sociology, anthropology and clinical psychology. This resulted in a new emphasis on the customer as a unit of analysis. As a result, new substantive knowledge was added to the marketing discipline - including such ideas as opinion leadership, reference groups and brand loyalty. Market segmentation, especially demographic segmentation based on socioeconomic status (SES) index and household life-cycle, also became fashionable. With the addition of consumer behaviour, the marketing discipline exhibited increasing scientific sophistication with respect to theory development and testing procedures.
In its early years, consumer behaviour was heavily influenced by motivation research
which had increased the understanding of customers, and had been used extensively by consultants in the advertising industry and also within the discipline of psychology in the 1920s, '30s and '40s. By the 1950s, marketing began to adopt techniques used by motivation researchers including depth interviews, projective techniques, thematic apperception tests and a range of qualitative and quantitative research methods. More recently, scholars have added a new set of tools including: ethnography, photo-elicitation techniques and phenomenological interviewing. Today, consumer behaviour (or CB as it is affectionately known) is regarded as an important sub-discipline within marketing and is included as a unit of study in almost all undergraduate marketing programs.
For most purchase decisions, each of the decision roles must be performed
not always by the same individual. For example, in the case of family making a decision about a dining-out venue, the father or mother may initiate the process by intimating that he/she is too tired to cook, the children are important influencers in the overall purchase decision, but both parents may act as joint deciders performing a gate-keeping role by vetoing unacceptable alternatives and encouraging more acceptable alternatives. The importance of children as influencers in a wide range of purchase contexts should never be underestimated and the phenomenon is known as pester power.