What effect does the fundamental distinction between object and action concepts have on psycholinguistic processes like the processing and acquisition of nouns and verbs and susceptibility to error in that connection? In an attempt to answer this question the study (a) describes experiments and empirical studies involving children and adults with and without language disturbances, and (b) compares acquisition processes in German, Korean, Turkish, and English. The findings indicate differential processing and acquisition sequences for nouns and verbs. This outcome serves as the basis for a discussion of the status of parts of speech in human cognition.