Inez Tan

This paper reports an investigation into the nature of Negative Polarity Item (NPI) licensing conditions from a processing perspective. We found that the processing cost of Downward Entailingness (a k a the Monotonicity Effect) is determined by the number of monotonicity reversals of NPI domains, rather than by the number of Downward-Entailing (DE) operators. This conclusion is not based on the standard judgment paradigm, but rather, on the measurement of continuous variables (error rates, Reaction Times (RTs)) in a verification task, in which the truth value of a sentence is determined against a scenario. We conducted two experiments with sentences that contained one or two DE operators, which featured in different syntactic configurations. We explored how RT is affected by the manipulation of both the number of DE operators, and the syntactic environments in which they reside. We ran these experiments in Hebrew and in English, with different participant populations and different testing methods. Despite the linguistic subtlety of the theoretical issues, our results were remarkably sharp, leading to two firm conclusions: (i) that processing time is determined not by the number of DE operators, but rather, by the monotonicity of the minimal constituent in which they reside; (ii) that DE-ness is not a property of operators, but of environments. We show how our results bear directly on the current debate about the nature of monotonicity, which we describe below. Finally, we provide quantitative tests of alternative, non-semantic explanations, and show how our results do not support them.