INDIVIDUAL-DIFFERENCES AND PROBABILISTIC CONSTRAINTS IN SYNTACTIC AMBIGUITY RESOLUTION

Two experiments investigated the role of individual differences in reading span in the comprehension of ambiguous sentences that were resolved with a syntactically simple interpretation. Previous research showed that high but not low reading span subjects had longer reading times for such sentences compared to unambiguous controls, a result that had been attributed to high span subjects maintaining more alternative interpretations of the ambiguity than did low span subjects (MacDonald, Just, & Carpenter, 1992). Experiment 1 replicated this reading time pattern but also showed that the individual differences were attributable to differential sensitivity to probabilistic constraints in the stimuli, in that only high span subjects were sensitive to the relative plausibility of alternative interpretations of the ambiguity. Experiment 2 demonstrated that the source of these differences was in the ability to use plausibility constraints during comprehension, not in constraint knowledge across the two groups. The implications of these results for studies of individual differences and for theories of syntactic ambiguity resolution are discussed. (C) 1995 Academic Press. Inc.