Contribution of working memory in parity and proportional judgments

This paper presents experimental evidence on the differences in a sentence–picture verification task under additional memory load between parity and proportional quantifiers. We asked subjects to memorize strings of four or six digits, then to decide whether a quantified sentence was true for a given picture, and finally to recall the initially given string of numbers. The results show that: (a) proportional quantifiers are more difficult than parity quantifiers with respect to reaction time and accuracy; (b) maintaining either four or six elements in working memory has the same effect on the processing of parity quantifiers; (c) however, in the case of proportional quantifiers subjects perform better in the verification tasks under the six-digit load condition, and (d) even though the strings of four numbers were better recalled by subjects after judging parity there is no difference between quantifiers in the case of the six-element condition. We briefly outline two alternative explanations for the observed phenomena rooted in the computational model of quantifier verification and the different theories of working memory.