MEASUREMENT AND SIMULATION OF COLOUR SENSATIONS

Colour vision has a causal chain structure. The chain consists of an electrical neuronal processing part, coding for the amounts of elementary colour sensations (elementary colours), as well as for the spatial locations of the composed colour sensations (colours), and finally of the elementary colour sensations per se. The composed colour sensations consist of six elementary colours, which differ qualitatively from each other. On the other hand, the electrical membrane potentials of the neurones are always one physical quality only, even when superimposed from several neurones and vary over time. This ontological gap in the physiological description of colour vision was, therefore, investigated as a black-box with the electrical excitations of the colour coding (CC) neurones as the input, and the amounts of the elementary colours (EC) as the output. The general properties of a psychophysiological model of colour sensations were theoretically determined, and measured in psychophysical experiments in conjunction with introspection. The results of these investigations are presented and discussed. Spatial colour perception turned out to have in the order of 10¹⁶ colour locations, allowing for hyperacuity judgements. The necessary colour and spatial information can actually be provided by the much smaller number of neurones in the cortical visual areas. The psychophysiological model of colour sensations is expected to finally enable us to identify the materials that are close to or even identical to the elementary colour sensations.