From opposites to dimensions: filling in the gaps.

In most of cases, when referring to contrariety, psychologists also refer to dimensions, implying the existence of a latent trait which connects one pole to the other and which is characterized by a bipolar nature. In other cases the term “dimension” is used to refer to qualitative or quantitative gradations of a single property and in this sense their unidimensional nature is assumed. In this chapter, the authors start by pointing out that, in the literature which in one way or another has referred to the phenomenal-perceptual and conceptual correlates of antonymy, the question of the nature of dimensions and how they relate to the experience of contrary properties has never been addressed in a proper experimental research project. Focusing on perceptual and, in particular, spatial variables, the authors demonstrate that a series of considerations resulting from the application of set theory to descriptions of phenomenal experiences of contraries are enough to make one doubt that the idea of dimensions as continua comprising all the instances of two poles as well as those in between (intermediates) can be derived in a straightforward way from the perceptual experience of these three components. This is demonstrated with respect to various types of spatial contraries on the basis of some experimental data collected in psychophysical studies investigating their perceptual nature.