Predicting contrast in sentences with and without focus marking.

How do we know when a contrast is coming? This study explores the prediction of parallel contrastive phrases, especially NPs, in sentences with and without overt focus marking. A written sentence-completion questionnaire with clauses followed by the conjunction "but" compared unmarked initial clauses to ones with the focus marker "only" on the subject or object. Both conditions with "only" elicited more contrasts overall than the condition without focus marking, and many of the contrasts were with the focus-marked NP. While the baseline (no-only) condition had full clauses for half of the completions, subject focus increased clausal completions and object focus increased negative ellipsis completions ("not"+NP structures), both changes in syntax which make a contrast with the marked NP easy. The production of negative ellipsis sentences primarily in the object-focus condition suggests that the object bias of these sentences in comprehension could relate to their being used more frequently with this meaning. Finally, the overall pattern of results shows that overt marking of contrastive focus increases continuations with contrasts, and the conjunction "but" does not reliably predict explicitly-stated contrasts within a sentence without overt focus marking.