Addendum: Colour categories in a stone-age tribe

Colour categories in a stone-age tribe J. Davidoff, I. Davies, D. Roberson Nature 398, 203–204 (1999)

The colour-naming pattern of Berinmo speakers may appear consistent with that obtaining in tritanopia¹, a colour-vision disorder that has an increased frequency in other tropical areas² and can arise from chronic exposure to short-wavelength light³. Furthermore, it could be argued that an isolated tribe may have become tritanopic through a shared genetic defect. However, our Berinmo speakers were not tritanopic. They were tested with the City University Colour Vision Test⁴ that specifically assesses tritanopia. The test consists of ten plates, and all speakers who failed any of the plates were eliminated from our study. The failure rate was 7 out of 83 speakers tested during the course of the study.