In this article, I analyze how interests affect the results of scientific change through concept representation and categorization. I first review two models offered by cognitive psychology, which use frames as the representational structure to account for how interests actually affect concept representation and categorization. I then use a historical case from nineteenth-century optics to illustrate how the interests of historical figures influenced their concept representations, then their classifications and finally the results of their theory appraisal. I conclude that the impact of interests on science is constrained by the states of the world and interests alone can never decide the results of scientific change.