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On the acquisition of grammatical morphemes

In his classic longitudinal study on the acquisition of 14 English grammatical morphemes, Brown (1973) concluded that the order in which they were acquired was independent of their frequency of use in parental speech, but that the order was predictable from the morphemes' syntactic and semantic complexity. Since these two complexity measures were highly confounded in the 14 morphemes, their respective influences on acquisition order were indistinguishable. Similar results were obtained in a cross-sectional study conducted by de Villiers & de Villiers (1973). In a recent issue of this journal, two articles appeared which attempted to revise these conclusions by reanalysing Brown's data. Moerk (1980) claimed that certain subsets of the data show that frequently heard morphemes are mastered earlier; Block & Kessel (1980) claimed that a different statistical treatment of the data indicate that it is neither syntactic nor semantic complexity but some third factor underlying both that determines acquisition order. In this note I argue that each of these analyses contains methodological and logical errors, and that Brown's original conclusions still stand.