Discourse under control in ambiguous sentences

A recent topic in language acquisition is children’s comprehension of sentences containing multiple scope-bearing elements. The main problem posed by those sentences is that the relative scope of each operator might be reversed and children need to relate a single sentence to two distinct logic representations. Sometimes languages have means to reduce ambiguity, as in negative sentences, where quantifiers present a specification relative to their polarity. However, also this information needs to be acquired, and even if there is evidence that children are sensitive to polarity from early on (Thornton, 1994), several studies have shown that under certain circumstances, children interpret multiple-operator sentences differently from adults. Initial findings by Musolino (1998) and Musolino et al. (2000) suggested that in an early developmental stage, scope assignment adheres to surface structure relations. This means that the surface c-command relations observable at PF are also respected at LF, resulting in an Isomorphic LF-PF mapping. This view has been successively questioned by more recent studies (Gualmini 2004a, Husley et al. 2004, Kramer 2000) which challenge the conclusion that surface relations determine scope assignment. According to Husley et al. (2004), structural relations are not the only way to look at the phenomenon and a closer observation to the link between a sentence and the discourse can explain children’s deviant interpretations. If one possible interpretation is contextually inappropriate, it will be disfavored, regardless of surface c-command relations between logic elements. Additional evidence against Isomorphism comes from the study of modality. Moscati & Gualmini (2008) looked at modal verbs, instead of nominal quantifiers, in negative sentences. Consider the examples in (1) and (2):