In this article it is pointed out that there exists a methodological contradiction in most research on cognition and cognitive processes, which makes such research invalid in the strongest meaning of the term. When the aim is to study cognitive processes very often the researcher uses attributes of the learning material to be the standard or the template against which any outcome of the subjects can be analysed and made the ground for inferences about cognition and cognitive processes. This way of doing research is considered to be based on false theoretical assumptions and also proven invalid by a number of empirical studies. It is suggested in the article that the researcher must distinguish between an educational and a cognitive perspective and avoid mixing them in order to carry out successfully research on cognitive processes.