Bilingualism and performance on the WISC-V – findings from the FinSwed study

Information about the relationship between bilingualism and performance on comprehensive intelligence tests is still scarce. This study compared test performance on the Swedish WISC-V between monolingual Swedish-speaking (n = 110) and bilingual Swedish-Finnish-speaking (n = 84) 6–16-year-old children from Finland. The bilinguals spoke both languages at home and were regularly exposed to both before the age of 1. All participants attended Swedish-speaking schools or pre-primary schools in Finland. The results showed no significant main effects of bilingualism on the subtest level, the primary index level, or the Full Scale IQ. However, monolingual children scored significantly higher on the Vocabulary subtest and the Verbal Comprehension Index than bilinguals, and the opposite was found for the Symbol Search subtest. The results demonstrate the need to take bilingualism into consideration in clinical assessments to avoid misinterpretations of bilinguals’ verbal reasoning skills.