Why is colour naming difficult?

A suggestion exists in the child language literature that the meanings of natural kind terms are acquired before the meanings of colour terms. Explanations have typically claimed that object terms are more salient than property terms. Such explanations, however, tend to ignore the fact that natural kind terms refer to categories with sharp, clear boundaries while colour terms refer to categories with unclear or variable boundaries. Nonetheless, there has been little evidence to show that the delay in the acquisition of colour terms arises from these semantic properties. This study compares natural kind and colour naming (and corresponding comprehension) by 48 children, ranging in age from 3;0 to 5;5. The results suggest that, contra the salience view, the apparent delay in colour naming may be explained on solely semantic grounds.