Abstract
This study advances the research scope of adverse extension effects by examining the impacts of brand similarity upon the accessibility of negative extension information. The research results reveal that the accessibility of unfavorable extension information of narrow brands is higher than that of broad brands. Negative extension information exerts more adverse effects on narrow brands than on broad brands. Narrow brands are high-similarity brands implying the existence of obvious underlying essence, which facilitates spontaneous processing of negative extension information. Contrarily, broad brands are lowsimilarity brands implying vague underlying essence, which leads to less spontaneous processing of negative extension information.