When numbers are not exact: Ambiguity and prediction in the processing of sentences with bare numerals

It is generally assumed that bare numerals (e.g., three) have two readings: the exactly and the at least reading. It has been a matter of debate whether one of these two readings is derived from the other pragmatically. To shed light on this question research has aimed at characterizing the processing demands associated with these alternative interpretations. Here we use a sentence-picture verification paradigm where participants are asked to judge whether "N pictures contain Xs" is true in a situation where (a) exactly N, (b) fewer than N, or (c) more than N pictures contain Xs. The critical case is the last one, where accepting responses indicate the at least interpretation of the numeral, whereas rejecting responses indicate the exactly interpretation. We show that the responses linked to the exactly and at least readings lead to quantitatively different event-related brain potentials (ERPs), which presumably reflect different cognitive processes. For the exactly responders, the ERPs elicited by content nouns downstream from the quantifier phrase formed a negativity effect in the condition with more than N Xs, relative to the condition with exactly N Xs. However, no such effect was evident for the responders who applied the at least interpretation. We argue that the lack of any ERP effect for the at least responders is not compatible with any theory presupposing an exactly semantics of numerals. The observed N400 effect is furthermore shown to be modulated by the type of alternatives presented in the context scenario. (PsycINFO Database Record (c) 2019 APA, all rights reserved).