Directions from shape: how spatial features determine reference axis categorization

Abstract

This paper presents three experiments on Dutch directional nouns, like voorkant ‘front’, and prepositions, like voor ‘in front of’. The first two experiments focus on the intrinsic meaning of these terms in relation to the horizontal plane. The experiments show that the following spatial features of a reference object determine reference axis categorization: (a) axis length, (b) contour expansion, and (c) curvature of the main plane of symmetry. On the basis of the first two experiments, as well as insights by Clark (1973), Tversky (1996) and Landau and Jackendoff (1993), the Spatial Feature Categorization (SFC) model is formulated. This model generates predictions on reference axis categorization derived from the spatial features of a reference object for the purpose of intrinsic directional reference in both the horizontal and the vertical plane. A third experiment tests predictions by the SFC model in relation to Dutch directional nouns by using a new set of reference objects, a new experimental task, and by considering both the horizontal and the vertical plane. This experiment supports predictions by the SFC model. It is argued that a system of categorized reference axes is necessary to represent local direction for the purpose of intrinsic directional reference. The categorization of the axes in such a system can be explained on the basis of the spatial features of a reference object