Beyond the conservative hypothesis: a meta-analysis of lexical-semantic processing in Williams syndrome

Abstract Williams syndrome (WS) is a rare genetic disorder, characterised at the cognitive level by a phenotypic pattern of relative weaknesses (e.g., visuospatial skills) and strengths (e.g., some linguistic and nonverbal reasoning skills). In this study, we performed a systematic search and meta-analysis on lexical-semantic processing in WS, an area of knowledge in which contradictory results have been obtained. We found 42 studies matching our criteria, and, in total, 78 effect sizes were included in the meta-analysis. Results showed that individuals with WS have worse lexical-semantic skills than individuals with typical development, whether matched by chronological or mental age. However, people with WS have better lexical-semantic skills than people diagnosed with other cognitive disabilities. Finally, vocabulary skills seem to be relatively spared in WS, although they present some difficulties in semantic processing/integration, semantic memory organisation and verbal working memory skills. Taken together, these results support a neuroconstructivist approach, according to which the cognitive mechanisms involved in lexical-semantic processing may be modulated, even when performance in some tasks (i.e., vocabulary tasks) might be optimal.