Verb form usage in Japanese EFL Texts

Recently, we applied the Posit textual analysis tools (PAAL, 2007) to conduct a frequency analysis on the range of vocabulary and multiword sequences used in three sets of historical Japanese EFL texts (PAAL, 2008): Barnes' New National Readers (published in 1883-84); Okakura, Yoshisaburo, The Globe Readers (published in 1907); and Jack and Betty: English Step by Step (published in 1948). The vocabulary used in the three textbook series exhibits a notable degree of similarity at the level of high frequency single words and small word sequences. Although variation in usage is greater as we consider larger multiword expressions, the comparative overlap of high frequency items may be expected since many of these terms and expressions will play common functional roles in grammatical sentence forms. In considering our findings from past and present textbook analyses, we suppose that careful design of language textbooks would take account of vocabulary coverage, as well as grammatical aspects. Accordingly, one expects more frequent use of those words that were regarded by the textbook authors as more important. Surprisingly, almost half of the individual words in each of the textbook series are used only once. This suggests that only a small proportion of words were considered important enough to merit frequent use (or, that little consideration was given to word usage aside from meeting the needs of grammatical construction). From a pedagogical perspective, emphasis upon grammatical structures may be achieved more effectively through diversity and richness in vocabulary. Related conclusions may be drawn regarding multiword hapax legomena. The textbooks show decreasing indication of attention to multiword usage as the multiword sequence size increases, with ~96% of 4-grams used only once in each textbook series. Our conjecture is that the high incidence of such hapax legomena reflects a lack of emphasis upon multiword sequences on the part of the textbook authors and that this, in turn, may be a side-effect of strong grammatical control. In the present paper, we test our assumption that the historical EFL textbooks exhibit priority of grammatical over vocabulary consideration, by profiling the use of verb forms in the three textbook series. Evidence of a managed application of verb forms across the volumes of any textbook series, particularly, with a rich variety of vocabulary exemplars, will reflect a focus upon grammatical control in textbook design. Coupled to our earlier results on vocabulary profiles, this would corroborate our view of emphasis upon grammar over vocabulary.