A considerable amount of research has been undertaken to establish how end users interpret, understand and verify data models often with the motivation of improving understanding, accuracy and completeness. However, there is relatively little research examining how and why humans make categorisation decisions when developing information systems. The research question addressed in this paper is: what is it about the human mind that allows it to categorise concepts in a particular way for conceptual data modelling? From a cognitive psychology perspective Lakoff’s (1987) image schema structures provide answers to such questions. I argue that acknowledging such structures is the first step in defining an experientialist strategy for data modelling. In addition a case example is used to illustrate the problems with utilising the objectivist approach to categorisation.