UC San Diego

This dissertation consists of three studies that discover and explore the novel copular function of a sign, SELF, which has cascading implications on our understanding of ASL nonverbal predication. First, a corpus study consisting of three epochs of historical ASL encompassing 150 years demonstrate SELF’s participation in a grammaticalization cycle that led to its primary function as a copula (Sampson & Mayberry 2022). In contrast to previous diachronic iterations, SELF in contemporary ASL appears most frequently in between the subject noun and an adjectival or nominal predicate in expressions of identity (A = B) and class membership (A is a member of set B), which are hallmarks of copulas. This finding is significant because it contradicts claims that there are no overt copulas in ASL. Second, an experimental study validated the finding that SELF functions as a copula in contrast to other potentially felicitous strategies in ASL nonverbal predication. To test the hypothesis, the distinction between individual-level (IL) predicates, which denote spatiotemporally immutable inherent features of an entity (e.g., deaf, plumber), and stage-level (SL) predicates, which denote spatiotemporally mutable features of an entity (e.g., busy, sit; Carlson 1977, Kratzer 1995), were compared with SELF and two other potential copular items: the covert null element (∅) and IX, a pronominal point. The Likert scale results show that SELF was preferred with IL nominal predicates, IX was preferred with SL verbal predicates, and there was no clear preference for the null element. Due to a conflation between the semantic and syntactic properties of the predicates used in the study, a third study was carried out with only adjectival predicates, to control syntactic category while varying semantic properties: SELF and IX were compared with adjectival predicates of either IL or SL properties. SELF was again preferred with IL adjectives and there was no preference for the sign IX in relation to IL or SL adjectives. These results attest to the markedness of SELF which, coupled with ASL consultants’ intuitions, suggest that SELF carries grammatical modality in marking assertions of truth and raises new important questions about copulas and nonverbal predication in sign languages.