According to the Common Ground account proposed by Stalnaker, speakers involved in a verbal interaction have different propositional attitudes towards presuppositions. In this paper we propose an experimental study aimed at estimating the psychological plausibility of the Stalnakerian model. In particular, the goal of our experiment is to evaluate variations in accepting as appropriate a sentence that triggers a presupposition, where different attitudes are taken towards the presupposition required. The study conducted suggests that if a speaker has the attitude of (...) belief towards the content of a presupposition, she may evaluate an utterance as more appropriate in a shorter time than in cases where she holds an attitude of presumption or of assumption. Therefore, data collected support the psychological soundness of what might be considered the main, but also most debated, theory of presupposition on the market. (shrink)