N400 as an index of uncontrolled categorization processing in brand extension.

This study examined the ERP (event-related potential) correlates of categorization processing in brand extension with irrelative task. Participants faced two sequential stimuli in a pair consisting of a soft drink brand name (S1) and a product name (S2) which comprised two categories: beverage (typical product of the brand, e.g. Coke branded soda water) and clothing (atypical product of the brand, even though sometimes it was seen in the real market, e.g. Coke branded sport wear). The N400 was recorded and more largely distributed in frontal, frontal-central and central areas when S2 was clothing compared with beverage. The study did not require the participants to evaluate that the brand extension was appropriate or not, the N400 recorded here was, therefore, irrelative to the task difficulty and the conscious categorization process. We speculated that it reflected an integration processing related with the mental category. The brand performed the role of prime which aroused the participants' association of the brand-related typical products and attributes retrieving from their long term memory. The product name activated an unconscious processing of comparison between the brand and the product. In this process, the participant treated the brand as a mental category and classified the product as a member of it. There would be a large cognitive reaction which elicited the N400 if the product's attributes were atypical to the category of the brand. These findings might help us understand the N400 component in unconscious mental categorization and supported the categorization hypotheses in brand extension theory which was crucial in consumer psychology.