The Rise and Fall of the L-Shaped Morphome: Diachronic and Experimental Studies

Abstract: It has been suggested that the Romance first person singular indicative forms a base of derivation for the subjunctive paradigm, even though the latter shares no morphosyntactic features with the former (Maiden, 2004). The existence of such patterns has been taken to be an argument for autonomous morphology and the existence of unnatural ‘morphomes’, in the sense of Aronoff (1994). Experimental investigations with native speakers of Portuguese, Italian, and Spanish reveal that this pattern is underlearned, and that speakers do not generalize it to novel forms, and instead prefer the 2nd person singular indicative to the 1st person as the base for the derivation of the subjunctive paradigm. The results implicate a role for naturalness biases in morphological structure, and an awareness that the first person singular is an unreliable and idiosyncratic base for productive inflectional identity. We further demonstrate, through means of diachronic corpus studies spanning five centuries, a change in the ratio of first conjugation verbs to second & third conjugation verbs. If indeed learners need increased evidence in order to incorporate and actively uptake unnatural patterns, this lexical support has dwindled over time. Even though many of the morphomic verbs have maintained a very high token frequency (allowing them to survive as memorized), their type frequency has diminished over time, and hence they go unlearned as a generalizable pattern. When the distribution of irregular alternations is overshadowed in the lexicon, a morphologically unnatural pattern may cease to be productive.