Another difficulty on the road to King's colour-blind America concerns higher education.

ECONOMIST: Forty years after the murder of Martin Luther King

Another example is Japan's National Bicycle Company, which turns out bikes in any size, colour or style without any increase in costs or delivery time.

ECONOMIST: Direct hit

Since 1976, Paul Kay of the University of California, Berkeley, another of the paper's authors, has compiled a database of information about how 110 different languages assign colour adjectives to 330 different hues.

ECONOMIST: Psychology