Attitudes from mere co-occurrences are guided by differentiation.

People often form attitudes about objects, individuals, or groups by examining and comparing their attributes. Such attribute-based attitude formation is guided by a differentiation principle: Whether people come to like or dislike an attitude object depends on the object's attributes that differentiate it from other objects. Attributes that are redundant with previously encountered attitude objects are typically cancelled out. We tested whether the same differentiation principle applies to co-occurrence-based attitude formation, also known as Evaluative Conditioning. This form of attitude formation describes the phenomenon that attitudes are influenced by positive or negative stimuli that have co-occurred with attitude object, but which are not inherent attributes of the attitude object itself. Across 7 experiments (N = 1611), we consistently found that co-occurrence-based attitude formation is guided by the same differentiation principle as attribute-based attitude formation. Specifically, participants' attitudes toward unknown brands were most strongly influenced by positive or negative stimuli that distinctly co-occurred with a specific brand, and that differentiated that brand from previously encountered ones. Stimuli that redundantly co-occurred with multiple brands had weaker influences on brand attitudes. The results further suggest that differentiation operates at the learning stage during which distinct stimulus co-occurrences enjoy a processing advantage. We discuss the present findings' theoretical and practical implications for attitude formation and identify differentiation as a possible cause of biased attitudes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).