Towards a pragmatics of negation: the interpretation of negative sentences in developmental dyslexia

In this paper, we present the results of an experimental protocol suggesting the existence of a close relationship between developmental dyslexia, the interpretation of negative sentences and Verbal Working Memory. Recent studies conducted on developmental dyslexia have demonstrated that it is strictly related to a deficit affecting the verbal component of Working Memory. Moreover, research on negation has revealed that negative sentences are more difficult to interpret than their affirmative counterparts. According to the Two-Step Simulation Hypothesis (Kaup et al. 2007), negative sentences require the construction and comparison of two representations, concerning respectively the expected and the asserted state of affairs: an operation remarkably demanding in terms of working memory resources. Significantly, the results of our experimental protocol, testing the comprehension of both active and passive negative sentences, have revealed that dyslexics show a very poor performance when they are asked to interpret negative sentences, whereas age-matched typically developing children accomplish the task almost effortlessly. These results are particularly interesting for two reasons: on the one hand, they corroborate the Two-Step Simulation Hypothesis, claiming that negative sentences are difficult to process, and, on the other hand, they provide new evidence to the hypothesis according to which dyslexia is related to a Verbal Working Memory deficit