The puzzle of number agreement with disjunction

In English, when two nouns in a disjunctive subject differ in number (e.g., the dogs or the cat), the verb tends to agree with the number of the nearer noun. This is exceptional, as a noun's linear proximity to the verb does not generally play a role in agreement. In the present study, we investigate a further puzzle about agreement with disjunction, namely, the existence of a pattern in which two singular disjuncts trigger plural agreement (e.g., The lawyer or the accountant are…). Two eyetracking studies in English show that plural agreement with a disjunction of singulars does not reliably disrupt readers' eye movements, in contrast to the immediate disruptive effect of other agreement violations. Three off-line rating studies in English show that plural agreement results in only a small decrement in acceptability, compared to other agreement violations, and that in some structural configurations there is no decrement at all. On the whole, the data do not support the hypothesis that plural agreement is licensed only when or has an inclusive reading; even when it has an exclusive reading, there is only a small penalty for plural agreement. Finally, we explored this issue in Italian, which has a richer system of inflectional morphology. Italian speakers showed a plural preference in a completion experiment, and singular and plural agreement did not differ in acceptability in a rating experiment. We conclude that agreement with disjunction is a grammatical lacuna or gap, in the sense that speakers' grammar simply does not prescribe a verb number following a disjunctive subject.