This dissertation discusses how pragmatic factors contribute to children's behavior in interpreting scopally ambiguous forms. In particular, we look at children's interpretation of negated sentences involving disjunction in the object (NegDisjunction). Languages like English and Chinese allow scope interaction between negation and disjunction of this kind of strings and thus two corresponding interpretations: the narrow scope disjunction interpretation (the NSD, meaning "neither"), thus the wide scope disjunction interpretation (the WSD, meaning "not this or not that"); but languages like Japanese only allow the WSD. Previous studies found out that children of different languages accessed the NSD instead of the WSD given "not this or not that" scenarios (e.g., Crain, Gualmini & Meroni 2000; Goro & Akiba 2004a; Jing, Crain & Hsu 2005) and concluded that preschool children systematically lack the WSD in their grammar. However, given the fact that the WSD is pragmatically more complex than the NSD, and the well documented observations that children's immature capacity in pragmatic computation sometimes masks their linguistic competence (e.g., Gualmini 2004; Musolino & Lidz 2006), the findings in previous studies could reveal children's strong preference toward the NSD rather than their lack of the WSD.

Four main experiments, which aim to test the hypothesis that children's grammar can generate the WSD and that children can access this interpretation when the relevant pragmatic computation is facilitated, are reported in this dissertation. During various experimental manipulations designed to facilitate children's pragmatic computation, we observed that children accessed the normally dispreferred WSD more often, when the "not this or not that" meaning was made more directly relevant in the context, when explicit disambiguating information was present in the discourse, after they were trained to be more sensitive to the "not this or not that" aspect of the context, and after they immediately experienced the use of certain alternative form (NegConjunction) to express the "neither" meaning (corresponding to the NSD of NegDisjunction).

The findings in these experiments reveal children's hidden grammatical knowledge of the WSD and highlight the role of pragmatic computation in the acquisition of meaning.