Adjectival polarity and the processing of scalar inferences

In a seminal study, Bott & Noveck (2004) found that the computation of the scalar inference of ‘some’ implying ‘not all’ was associated with increased sentence verification times, suggesting a processing cost. Recently, van Tiel and colleagues (2019b) hypothesised that the presence of this processing cost critically depends on the polarity of the scalar word. We comprehensively evaluated this polarity hypothesis on the basis of a sentence-picture verification task in which we tested the processing of 16 types of adjectival scalar inferences. We develop a quantitative measure of adjectival polarity which combines insights from linguistics and psychology. In line with the polarity hypothesis, our measure of polarity reliably predicted the presence or absence of a processing cost (i.e., an increase in sentence verification times). We conclude that the alleged processing cost for scalar inferencing in verification tasks is not due to the process of drawing a scalar inference, but rather to the cognitive difficulty of verifying negative information.