The Role of Derivational Morphology in Vocabulary Acquisition: Get by with a Little Help from My Morpheme Friends

This study explores the role of morphology in vocabulary knowledge of 3rd and 6th grade Finnish elementary school children. In a word definition task, children from both grades performed overall better on derived words than on monomorphemic words. However, the results were modified by the factors Frequency and Productivity. Most strikingly, performance on monomorphemic words was disproportionately weaker than on derived words at the low frequency range. At the high-frequency range, derived words with low-productive suffixes yielded poorest performance. We partly make an appeal to the lexical-statistical properties of the Finnish language to explain the interaction of Frequency and Word Structure. At any rate, the results suggest that Finnish elementary school children benefit significantly from utilizing morphology in determining word meanings.