Abstract
Generally, it has been assumed that the task of stimulus discrimination differs from that of categorisation; exemplar-based theories challenge this assumption. It was recently shown that both the discrimination and categorisation of cardinal colours may be explained by the same underlying similarity judgement space. Further, we have found that similarity judgement of cardinal colours are best fit by an elliptical deformation of the cardinal colour plane into a perceptually equal space. Here we extend these data by examining how similarity judgements change as the amount of information on each sample is reduced. Observers were required to judge, on a scale of 1-8, the degree of similarity between 210 pairs (21 colours) of scaled, equiluminant cardinal colour patches presented for 100msecs. The paradigm and stimulus structure was exactly the same as used for the previous discrimination and categorisation measurements; only the observer judgement changed. The data were analysed using multi-dimensional scaling to give a psychological similarity space for each subject. We found few systematic differences between the MDS spaces for the same group of subjects as in the longer duration study despite the brief stimuli. We discuss this in terms of exemplar-based theories of categorisation.
Meeting abstract presented at VSS 2017