The Nature of Similarity in Perceptual Colour Space.

Lead Research Organisation: University of Bristol
Department Name: Experimental Psychology

Abstract

How do we tell how similar two objects are? The nature of similarity is crucial to how we understand the world, and how we generalise to "similar" but not identical situations, but we propose that the nature and geometry of our representations is at least partly determined by what we use them for. If we simply want to discriminate two simultaneously presented coloured patches, then the fundamental limitation is due to photoreceptor noise, and similarity should be (at least partly) determined by how confusable the two patches are in the presence of this noise. Such spaces have been intensively studied, and the powerful techniques of informational geometry have provided insight into the nature of the (low level) representations of space we have. Simple discrimination, though, is not the main use of perceptual signals such as colour, and the nature of the task should also determine the space: if I am simply wanting to discriminate flowers from leaves, then the distance from brown to green should be large (since this is on average discriminatory), whereas that between blue and orange should be short since this discrimination will rarely be important.
The studentship will look at the problem of task dependent representations, how they are learnt, and investigate their characteristics for problems in colour perception. Using the tools provided by information geometry, we will look at both the practical (what colour discriminations are important for given tasks), and the theoretical (how do we characterise the geometry of these spaces). Colour is perfect for this because it is a relatively low dimensional signal, is clearly behaviourally important, but whilst we have a good characterisation of the (receptor based) spaces that characterise simple discrimination, we have a far less good grasp of the representations involved in large colour differences and those used in memory and identification.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509619/1 01/10/2016 30/09/2021
2063570 Studentship EP/N509619/1 01/11/2017 30/04/2021 Mubaraka Muchhala