In a seminal study, Bott and Noveck (2004) found that the scalar inference from
‘some’ to ‘not all’ was associated with increased sentence verifcation times, which
they took to show that scalar inferences are associated with a processing cost.
Recently, van Tiel, Pankratz, and Sun (2019) hypothesised that the presence of
this processing cost critically depends on the polarity of the scalar word. We
comprehensively and systematically evaluated this polarity hypothesis on the
basis of a sentence-picture verifcation 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 psychology and linguistics. In
line with the polarity hypothesis, this measure of polarity reliably predicted the
presence or absence of a processing cost, i.e., an increase in sentence verifcation
times. We conclude that the alleged processing cost for scalar inferencing in
verifcation tasks is not due to the process of drawing a scalar inference, but rather
to the cognitive difculty of verifying negative information.