Vocabulary knowledge predicts individual differences in the integration of visual and linguistic constraints

Two experiments investigated individual differences in the integration of visual and linguistic constraints during syntactic ambiguity resolution. Skilled adult comprehenders heard sentences like “Put the kiwi on the rectangle on the circle”, in which “on the rectangle … ” could temporarily reflect either the destination of “put” or a modifier of “kiwi”, while viewing visual arrays with either 1 kiwi (e.g. on a rectangle) or 2 kiwis (e.g. on a rectangle vs. triangle). While the noun “kiwi” provided sufficient information to distinguish the object of interest in the 1 referent context, modification was necessitated by the 2 referent context. Garden path eye (Experiment 1) and mouse (Experiment 2) movements to the incorrect (e.g. rectangle) destination were reduced in 2 vs 1 referent contexts, conceptually replicating prior findings, and these effects were weaker for participants with less vs. more vocabulary knowledge. Implications for models of sentence processing are discussed.