The paper is a theoretical and empirical contribution to the debate regarding the principle of language relativity in relation to ontogenesis. In the first part of the paper it is argued that the division between universal knowledge and culture-specific knowledge which is present in the new discipline of cognitive science is based on a false dichotomy. This has led to the ignorance of the complementary contributions that anthropology and developmental psychology may offer for the investigation of different human knowledge systems. The status quo regarding recent empirical evidence that demonstrates how language effects cognition is then presented and discussed in terms of ecological validity. The second part of the paper presents results fr...