Proceedings of the Annual Meeting of the Cognitive Science Society

A long-standing assumption in cognitive science has been thatconcepts are shared among individuals for common words.However, given that concepts are formed by the data we ob-serve, and observations vary wildly across individual experi-ences, our concepts are not likely identical. Here, we presentdata in which 104 participants answer questions regarding theirbeliefs about the definitions of common everyday words, andthe degree to which they think others agree. Our results sug-gest that even for common words, there exist many distinctextensions of ordinary and political concepts across individu-als. There is also a pervasive bias which leads individuals tooverestimate the degree to which others agree, which may ex-plain why “talking past each other” is an anecdotally commonexperience when discussing important topics.