ABSTRACT This project builds on prior NSF-supported research on the linguistic phenomenon of "unaccusativity", which involves a split among intransitive verbs into the unaccusative verbs, whose surface subject is an underlying object, and the unergative verbs, whose surface subject is an underlying subject. The investigation will now address two theoretical issues that surfaced in this work, both involving the proper lexical representation of verbs. They are: (1) meaning shifts, a phenomenon in which verbs regularly show several meanings, and (2) the identification of the basic number of arguments of a verb--its "acidity". Intransitive verbs are again the research domain. The results of these explorations will further deepen our understanding of unaccusativity. The focus will be on one manifestation of the important question of the "non-uniformity" of unaccusativity: if unaccusativity is syntactically represented, why is there a split among the uncontroversially unaccusative verbs, a syntactically-defined class? Since the split is reflected in behavior with respect to meaning shifts and adicity, the investigation of these issues will be brought to bear on explaining the non-uniformity of unaccusativity.
