Quantifier Raising in 4-year-olds

Four and five-year-old children, however, systematically rejected the inverse scope readings (3a/4a) of the quantificational expressions t w o birds/every horse in favor of the surface scope readings (3b/4b). We can refer to this result as “the isomorphism effect”: children, unlike adults, assign relative scope to negation and quantified NPs on the basis of their surface positions. Thus, although adults are aware of the imperfect mapping between surface syntactic structure and semantic structure, children seem to rely more heavily on the surface structure in assigning a semantic representation. An important question left open by these studies is why children differ from adults with respect to their ability to assign inverse scope. Why do children initially fail to assign inverse scope to ambiguous sentences containing a quantifier and negation? In principle, two types of explanation are possible. One explanation would hold that until a certain stage in grammatical development,