Selective attention along arbitrary axes

Abstract

Selective attention, the ability to emphasise the relevant properties of an object and de-emphasise the irrelevant ones, is a central process in psychological models of category learning. The properties that can be attended to, or psychological dimensions as they are known in the field, are commonly assumed to remain unchanged through the course of a categorisation task. In this paper we show that, under certain conditions, new dimensions may emerge during learning by collapsing existing psychological dimensions. We analysed three previously published data sets, each containing multiple categorisation tasks. Stimuli were Munsell colours varying along the dimensions of brightness and saturation. We found that, in some cases, subjects attended to axes in the psychological space that did not coincide with the psychological dimensions, i.e., they had formed new psychological dimensions. This was the case for diagonal tasks in which the category boundary is oblique with respect to the psychological dimensions. Unexpectedly, this was also the case for some dimensional tasks in which the category boundary is perpendicular to one of the psychological dimensions.