Russian blues reveal the limits of language influencing colour discrimination

Chromatic stimuli across a boundary of basic colour categories (BCCs; e.g. blue and green) are discriminated faster than colorimetrically equidistant colours within a given category. Russian has two BCCs for blue, sinij ‘dark blue’ and goluboj ‘light blue’. These language-specific BCCs were reported to enable native Russian speakers to discriminate cross-boundary dark and light blues faster than English speakers (Winawer et al., 2007, PNAS, 4, 7780-7785). We re-evaluated this finding in two experiments that employed identical tasks as in the cited study. In Experiment 1, Russian and English speakers categorised colours as sinij/goluboj or dark blue/light blue respectively; this was followed by a colour discrimination task. In Experiment 2, Russian speakers initially performed the discrimination task on sinij/goluboj and goluboj/zelënyj ‘green’ sets. They then categorised these colours in three frequency contexts with each stimulus presented: (i) an equal number of times (unbiased); more frequent (ii) either sinij or goluboj; (iii) either goluboj or zelënyj. We observed a boundary response speed advantage for goluboj/ zelënyj but not for sinij/goluboj. The frequency bias affected only the sinij/goluboj boundary such that in a lighter context, the boundary shifted towards lighter shades, and vice versa. Contrary to previous research, our results show that in Russian, stimulus discrimination at the lightnessdefined blue BCC boundary is not reflected in processing speed. The sinij/goluboj boundary did have a sharper categorical transition than the dark blue/light blue boundary, but it was also affected by frequency and order biases, demonstrating that “Russian blues” are less wellstructured than previously thought.