Rule or rote ? Native-speaker knowledge of Japanese verb inflection

To investigate verb productivity in Japanese, an aural/oral production experiment asked adult native speakers to create inflected forms of nonce verbs. Naturalistic stimuli were used in order to tap speaker knowledge of verb paradigms and add psycholinguistic information to the traditional description of the verb lexicon. Four verb paradigms which are thought to be productive in modern Japanese were tested, and it was found that one type ( -oru) was significantly easier to produce than the others (-iru, -isuru, and -osuru). Results are discussed in terms of cue validity. Human language is governed by rules, or regularities, as linguists have shown. On the other hand, anyone who has tried to learn a language in adulthood knows that much of the job is sheer rote memory. Rule and rote—how much does each contribute to language use, and how can we tell which is which? One area of language that seems clearly divided between rule and rote is inflectional morphology. According to many linguistic analyses of European languages, forms of “regular” verbs (like offer, off e r ed) are generated by rule as needed, while for “irregular” verbs (like teach, taught ) each individual form must be recorded in the mental lexicon, since no rule can generate them (or at least, no rule shorter than the list of the forms themselves). Over the past 30 years, there has been a great deal of research to test this “dual route” hypothesis. Some of its opponents claim that all inflected forms are stored in the lexicon, both regular and irregular. Others cite recent connectionist models to show that distributed processes of analogy or pattern recognition could act on all verbs alike. This controversy is founded upon the assumption of two types of inflectional paradigms—“regular” and “irregular. ” In English, these two types are indeed clearly differentiated. In other European languages with richer morphology, such as Spanish, German, and Italian, there is more of a continuum, but still the dichotomy is a tenable one. Is this typology universal across languages? Can such a two-way distinction be made for Japanese verbs? “Regular” vs. “irregular” In the European languages for which this phenomenon has been studied, “regular” verbs have the following characteristics: 1. Predictability: The various inflected forms are completely predictable from the base form (“rulegoverned”), while irregular verb forms are idiosyncratic and arbitrary (though there may be “family resemblances” within subgroups of them). 2. Transparency: The various forms of a paradigm are phonologically and/or orthographically similar, and easy to decompose into stem+affix(es). 3. Productivity: The regular paradigm is used for new or unknown verbs. The first two characteristics are generally determined by linguistic analysis, but productivity needs both corpus data on new coinages and tests of how speakers actually conjugate novel verbs. Such an experimental methodology, the “nonceprobe” task, was begun with children, by Berko (1958) for English and MacWhinney (1975) for Hungarian, among others. Bybee & Pardo (1981) were the first to report testing adults. Adult native speakers of Spanish listened to a story being read in Spanish while looking at the illustrations. Nonce verbs were embedded in the story, and subjects were asked to supplied inflected forms orally where needed. The authors concluded that speakers were not making use of regularities that exist in the language: “Our subjects did not make the inference that seems logical from the point of view of a descriptive grammar of Spanish” (p. 941). Schnitzer (1996) tested the ability of native Spanish speakers in five different localities to conjugate nonce verbs resembling all three Spanish conjugation classes. Adult subjects listened to paradigms like: Antes, siempre yo rescopía, nosotros rescopíamos, ellas ___. ‘Before, I always X-ed, we X-ed, they (fem.) _____. ’ The subjects then orally filled in the blanks. Across the five groups, there were from 13% to 24% errors in conjugation class assignment. Clahsen (1999) reports nonce-probe experiments on German verbs, in which adult speakers overextended the more productive paradigm to nonce verbs, even those which more closely matched the less productive paradigm.