Perceptual ratings of opposite spatial properties: Do they lie on the same dimension?

The issue of unidimensionality is dealt with in various research areas in the field of Psychology (e.g. conceptualspaces, semantic modeling, psychometrics) and always involves spatial modeling. An investigation of thedimensionality of opposite spatial scales (even basic) has however not yet been carried out. In this paper welook at whether opposite judgments of height, size, width and length (high/low, large/small, wide/narrow, andlong/short) imply underlying unidimensional continua. In three experiments, independent ratings for the8 above mentioned properties were elicited with participants looking at photographic representations of variousobjects (Study 1), real life objects (Study 2) and spatial extensions in object-independent conditions(Study 3). Explorative and confirmative factor analysis and Andrich Extended Rating Scale Models were appliedin order to determine whether the ratings referred to opposite scales on the same linear continuum. Resultsfrom the three studies consistently revealed that this is not the case. A joint analysis of the data showedinteresting interactions between the spatial properties analyzed suggesting a possible explanation for thelack of unidimensionality.