Tieu, Lyn, Cory Bill, Jacopo Romoli, and Stephen Crain
Publication year: 2015

Abstract

Plural morphology in English is associated with a ‘more than one’ inference, which we refer to as a plurality inference, e.g., Emily fed giraffes Emily fed more than one giraffe. As with scalar implicatures, the plurality inference disappears in downward- entailing environments, such as when a plural appears in the scope of negation. This has led to the proposal that it should be derived as a kind of scalar implicature (Spec- tor 2007; Zweig 2009; Ivlieva 2013; Magri 2014). In this paper, we investigated this proposal in the domain of child language. There were two experiments. The first was conducted with adults and with 4–5-year-old children. The main finding was that both groups computed more plurality inferences in upward-entailing linguistic environments than in downward-entailing environments. Moreover, children computed fewer plural- ity inferences overall than adults did. This finding is consistent with previous research demonstrating children’s relative insensitivity to scalar implicatures. Taken together, the findings of the first experiment were consistent with a scalar implicature approach to plurality inferences. The second experiment tested different groups of participants on both plurality inferences and on classical scalar implicatures. Again, both the child and adult participants computed more plurality inferences in upward-entailing than in downward-entailing environments and, again, children computed fewer plurality infer- ences than adults did. More importantly, children’s performance on plurality inferences was highly correlated with their performance on classical scalar implicatures. We dis- cuss the implications of the findings for theories of plurality inferences, and for the acquisition of plurality more generally.