Threats to the External Validity of Brand Extension Research

The findings of prior research suggest that a brand's extendibility is constrained by the degree of perceived fit between the brand and extension product categories. However, there are many examples of brands that have been extended successfully into “perceptually distant” domains. Drawing on theories of consumer information processing and product adoption, the authors identify three background traits of prior work that may help explain the discrepancy between prior research and marketplace observation: (1) limited extension information, (2) failure to account for consumers' new product adoption tendencies (i.e., earlier versus later), and (3) single exposure to proposed extensions. In this study, the authors find that the effects of fit disappear when attribute information is added to extension stimuli and are applicable only for later product adopters. The authors also find that perceived fit increases with greater exposure to an extension. Beyond implications for brand extension research, this study underscores the need to recognize that certain research design factors related to external validity, which are often assumed irrelevant, can alter what is held to be true.