Publisher Summary This chapter explores that cognitive scientists study categories because the manner in which people perceive equivalences and make distinctions among objects reveals much about the mind's structure and function. It suggests that emotional responses provide a type of conceptual coherence. Specific emotional reactions to events render those events equivalent for the perceiver. The emotional response categories are probably implicit, in that the individual cannot necessarily articulate the rule of conceptual coherence. It discusses that the set of emotional response categories corresponds to a set of basic emotions, probably including happiness, sadness, fear, anger, and disgust. Some members of the categories are learned through experience, but there are probably innate constraints on the connections between emotional responses and naturally occurring stimuli. The relationship between emotional response categories and language is clearly important, but it is highly complex and requires much future research to generate quantitative models of emotional response categories and their connections to people's explicit knowledge of emotions and emotional language.