Abstract
The responses to diffusely-reflecting bodies occupy a sub volume of cone response space - the Body Colour Solid (BCS) [1,2]. In contrast to the continuous gradation of colour within the BCS stand the eleven Basic Colours (black, grey, white, red, orange, yellow, green, blue, purple, pink & brown) which, it is claimed, are concepts universal to developed societies. To bridge the gap between the continuity of the BCS and the discreteness of the Basic Colours, we hypothesize that the Basic Colour foci are located at landmarks of the BCS.
The shape of the BCS can be understood in the context of other solids that arise from ‘nearby’ systems of idealized cone functions. In particular: three delta functions; three Gaussian functions; a Gaussian function and its first and second derivatives [2,3]; a Gaussian function and its first derivative, plus a second Gaussian function partially overlapping the first. These comparisons allow us to explain these features of the BCS: (i) the pair of sharp apical vertices, (ii) the pair of blunted apical vertices, (iii) the system of high curvature creases over the surface, (iv) the exact centrosymmetry [4], (v) the approximate reflectional, 180° rotational [5], and 120° rotational symmetries.
The shape of the BCS immediately suggests landmark locations for the basic colour foci such that their relative positions match previously presented data [5] on their similarities, lightness and adjacencies. We have not yet tested the crucial question of whether the landmark locations correspond to the Basic Colour foci in the way that we predict.