Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Commerce, Law and Management, Graduate School of Business Administration, 201 / This dissertation examined the role of brands in consumer decision making in online environments versus offline environments. The effects of the information type and quality available in a given purchase environment influences consumer choice. The premise on which this study was based is the accessibility-diagnociticity model which states that the weight given to any piece of information which would be used for consumer decision making depends on the accessibility of that piece of information, the accessibility of alternative inputs and diagnositicity or perceived relevance of the inputs (Feldman & Lynch 1988). Information available to consumers plays a significant role in their decision making and there has been limited studies investigating this in the online versus offline shopping environments. The challenge of online shopping for some product categories is that there is limited capacity to provide touch, smell and taste information. The dissertation reports three experiments which were conducted to test the hypotheses. Participants were randomly assigned to different shopping environments with varying levels of information. The findings extend the theory of the diagnosticity of information (Alba, Hutchinson, & Lynch, 1991; Feldman & Lynch 1988; Herr, Karde, & Kim, 1991; Lynch, Marmorstein & Weigold, 1988; Lynch 2006) indicating that, when consumers observe that they do not have enough information to make a purchase decision, they do not make a decision unless the brand is familiar. vii The findings from the research offer fresh insights that familiar brands have greater advantage in online shopping than unfamiliar brands, particularly for experiential products. The results suggest that in purchase situations where there is limited sensory information, consumers rely on brand familiarity to make decisions or they do not make a decision if the brands are unfamiliar. The results of the dissertation showed that when there is limited information in consumer decision making processes, consumers use their knowledge about brands to make or not make a decision. The results contradict the long tail theory (Anderson, 2006) which proposes that the businesses would make more profits from niche offerings of unfamiliar brands. The results of the study were not conclusive on the effects of shopping environments on price sensitivity for familiar and unfamiliar brands. The results suggested the predicted pattern, though the interaction was not statistically significant and there is need for future research on online price elasticity. Future research should also explore the effects of these new sources of information like blogs, consumer and expert reviews, Facebook, etc. on consumer decision making in the offline and online environments