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.