The speech of people with Williams Syndrome (WS) has been widely reported to be incoherent at the discourse level and characterized as a ‘cocktail party speech’; that is, it seems to be mainly oriented towards social interaction rather than actual content. In contrast with the majority of the literature, we tend to point to phrasal meaning processing rather than purely lexical meaning to be the base of coherence and truth problems. In other words, the discursive deficit that people with WS exhibit could be due to a lack of referential anchoring at the phrasal

level, in which grammar and lexicon interact.  The core of the study is a comparison of electrophysiological response profiles in control participants and adult with WS for violations of semantic subcategorization restrictions at a grammatical level using EEG. We complement this study with an detailed analysis of fluency, semantic aspects and conversational aspects using a corpus of spontaneous speech.