Lightness and hue perception: the Bezold-Brücke effect and colour basic categories

Using surface colours as stimuli, the present research was aimed at the two following goals: (1) To determine the chromatic angles related to categorical effects type B-B (Bezold-Brücke). (2) To determine the colourimetric characteristics compatible with each Spanish colour basic category. To get these goals the full set of tiles included in the NCS (Natural Colour System) was used in a monolexemic naming task. Results showed that the use of chromatic categories was not only influenced by chromatic angle (Hu'v') but also by saturation (Su'v') and lightness (L*). This last parameter had a decisive influence on the responses to half of the chromatic circle (from G50Y to R50B, in terms of NCS nomenclature). Specifically, frequent B-B type categorical effects appeared: stimuli with the same chromatic angle, but different lightness being named differently.