Taking on semantic commitments, II: Collective versus distributive readings.

In earlier work, Frazier and Rayner (1990) provided evidence for a processing principle termed the Minimal Semantic Commitment (MSC)hypothesis. In the present study, we used the MSC hypothesis as a starting point in addressing the issue of when to treat mental representations as vague versus determinate and ambiguous. Given ambiguous representations, the MSC hypothesis predicts that the processor will commit to one interpretation (the grammatical ambiguity hypothesis). On the other hand, given a single underspecified representation, the MSC hypothesis predicts that the processor will await disambiguating information before fully committing to an interpretation (the vagueness hypothesis). In an experiment designed to evaluate these hypotheses with respect to the representation of distributivity, participants' eye movements were recorded as they read sentences containing distributive or collective predicates that were either disambiguated by a preceding adverb or left locally ambiguous by delaying the disambiguating adverb until the end of the predicate. The results suggested that a semantic commitment is made in locally indeterminate cases as evidenced by a significant interaction of ambiguity and distributivity in first pass times, total times, and regressions. If the difficulty of distributives simply reflected the difficulty of postulating a distributive operator when evidence warranting it is encountered, then no interaction would be expected. Hence we argue that the distributive/collective distinction is treated as a matter of ambiguity rather than as one of vagueness. In the absence of evidence for a distributive reading, the processor commits itself to a collective reading sometime during the processing of the predicate (before the disambiguation in our late disambiguation examples). The findings are discussed in relation to recent linguistic work on the representation of distributivity.