Proceedings of the Annual Meeting of the Cognitive Science Society

Features differ in their mutability. For example, a robin could still be a robin even if it lacked a red breast; but it would probably not count as one if it lacked bones. I have hypothesized (Love & Sloman, 1995) that features are immutable to the extent other features depend on them. We can view a feature's mutability as a measure of transformational difficulty. In deriving new concepts, we often transform existing concepts (e.g. we can go from thinking about a robin to thinking about a robin without a red breast). The difficulty of this transformation, as measured by reaction time, increases with the immutability of the feature transformed. Conceptual transformations are strongly affected by context, but in a principled manner, also explained by feature dependency structure. A detailed account of context's effect on mutability is given, as well as corroborating data. I conclude by addressing how mutability-dependency theory can be applied to the study of similarity, categorization, conceptual combination, and metaphor.