Philosophy, Psychology and Neuroscience

"What colours do the colour blind really see?"

Dichromatic colour vision is commonly believed to be a reduced form of trichromatic colour vision (referred to as the reductionist principle). In particular, the colour palette of the dichromats is believed to be a part of the colour palette of the trichromats. As the light-colour palette differs from the object-colour palette, the dichromatic colour palettes have been derived separately for light-colours and object-colours in this report. As to light-colours, the results are in line with the widely accepted view that the dichromatic colour palettes contain only two hues. However, the dichromatic object-colour palettes have proved to contain the same six component colours which constitute the trichromatic object-colour palette (yellow, blue, red, green, black, and white). Moreover, all the binary and tertiary combinations of the six component colours present in the trichromatic object-colour palette also occur in the dichromatic object-colour palettes. Yet, only five of the six component colours are experienced by dichromats as unitary (unique) object-colours. The green unitary colour is absent in the dichromatic object-colour palettes. The difference between the dichromatic and trichromatic object-colour palettes arises from the fact that not every combination of the component-colour magnitudes occurs in the dichromatic object-colour palettes. For instance, in the dichromatic object-colour palettes there is no colour with the strong green component colour. Furthermore, each achromatic (black or white) component colour of a particular magnitude is combined with the only combination of the chromatic components. In other words, the achromatic component colours are bound with the chromatic component combinations in dichromats.