Co-brand is a common strategy nowadays adopted in business, and is also one of strategies regarded as reconstruction, expansion or entering a new market. On the strength of new "co-brand" image, the purpose of companies is to emphasize and boost over the product judgment of original brand (a neutrally perceived brand, which is evaluated lower judgment in customers' mindset) by a positively perceived brand. Imperfectly, companies frequently do not consider that the positively perceived brand is also influenced by the original brand. That is, under co-brand condition the positively perceived brand may be judged lower than no co-brand condition. On the other hand, co-branding strategy is not only executed in the same industry and category, but often seen in dissimilar categories. In such condition, will the positively perceived brand be also affected by the original brand? What is the relationship between the two brands? How do they come about and change?
Present study is based on the theories of Context Effect and Reciprocity Hypothesis, which had been evidenced over co-branding strategy. When a target brand (neutrally perceived brand) is influenced by a context brand (positively perceived brand), assimilation or contrast effects will occur in the product's judgment. Comparatively, the context brand will also affected by the target brand even in the same or dissimilar categories. The hypotheses in present study are: assimilation and contrast effects to a context brand conducted by representation of target inclusion or exclusion and interpretation ranges overlap or non-overlap. The intension is that when a context brand is associated with a target brand, even from dissimilar categories based on these hypotheses, the context brand may be judged less favorably in customers' mindset. The target brand may be judged more positively in customers' mindset. The perceptions of reciprocal co-brand are the focus in this study. Therefore, the positively perceived brand should be carefully applied to co-branding strategy and deliberately adopted in real business.

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