Concept Formation in Dimensional Spaces

This article presents a series of experiments on concept formation. These experiments compared four different categorisation rules. The rules presume that the stimuli to be classified can be modelled psychologically as points in a dimensional space (Shepard 1987, Gärdenfors 1990a, 1990b). Two of the rules are based on the assumption that there are prototypical representatives of a concept, a third rule is a “nearest neighbour” model, and the fourth is based on average distances (Reed 1972), where distances are measured in the dimensional space. Before giving a more precise description of the categorisation rules and the experiments, we will present the general theoretical approach that is adopted.