In modern theories of consumer behaviour, much stress is given on this particular sequence of events of first knowing one's self and then proceeding to make a purchase. Experts believe "that people purchase a product or brand only if these things are consistent with, enhance, or in some way fit well with the conception they have of themselves" (Ross, 1971, p. 38). Thus, self-image, or self-concept has found a central place in the works of many modern consumer behaviour theorists.
"Any bit of knowledge that a person has about himself or the environment is a "cognition," or "cognitive element."" (Wicklund, and Brehm 1976, 2). Self-cognition is not objective, but the sum total of subjective thoughts one has about one's self. It is taken as "the totality of the individual's thoughts and feelings having reference to him/her self as an object" (Rosenberg, 1979). Modern consumer behaviour theories postulate that a consumer who is not aware of his/her self, and fails to achieve "self-congruity" is bound to suffer in the act of purchasing a product from pre-choice anxiety, and/or post-choice regret arising from cognitive dissonance.
In theories that attribute a "brand" with personality (Sirgy, 1985), the same principles can well apply to the development of the brand image of a product, as they apply to the consumer's path to proper purchase. Similar theorists hold that consumers select brands by the same process they select companions; "just as people take care in choosing friends who have a similar personality to themselves, so brands, which are symbolic of particular images, are chosen with the same concern" (De Chernatony and McDonald, 1997, p. 145). In today's marketing theories, products are assumed to have a personality that is not only determined by the product's physical characteristics (actual self), but also by the marketing mix promoting a brand image (ideal self) beyond the functionality of the product. In fact, according to many, self-image/brand-image congruity plays a key factor in driving consumer behaviour, and a brand image or product image, like the human self, can possess " a set of attributes such as friendly, modern, youthful and traditional" (Sirgy, 1985, p.195).
The concept of the self that a person holds has many dimensions, and includes both physical and psychological attributes. Self-concept bases itself upon human self-prototypes and moderates the psychological functioning of an individual to exhibit consistent behavioural patterns in the various social roles that a person has to play. Such self-prototypes or self-schemata control, organize, and influence the information processing function of a person that includes the processing of both self-related and other information (Markus, 1977). The selection, interpretation, filtration, and assimilation of incoming information depend upon the self-schemas possessed by each individual (Kihilstrom, 1981). Absorption, rejection, or alteration of new information is based upon its consistency with the existing self-structure (Snygg and Combs, 1949).
Earlier research on measuring and analysing self-images was confined to the domain of psychologists who studied the differences that could be seen between the individual's perceptions of his/her real