The Effects of Bilingualism on the Executive Control Abilities of the Prader-Willi Syndrome Population

Unlike with the typically developing population, non-typically developing individuals, especially those with intellectual disabilities, have usually been recommended to learn and use only one language, despite perhaps coming from bilingual families or living in multilingual environments. This common practice, however, is not backed by empirical evidence; previous research, although limited, has systematically shown that bilingualism does not have negative effects. This study investigates how bilingualism shapes the executive control abilities of individuals with genetic disorders. Specifically, we compare the interference suppression abilities of Spanish-Catalan bilinguals and Spanish monolinguals with Prader-Willi syndrome. Fifteen participants with Prader-Willi syndrome were recruited in Spain. The bilingual group consisted of seven Spanish-Catalan bilinguals from Catalonia-an officially bilingual territory of Spain-, while the monolingual group was formed by eight Spanish speaking individuals from Madrid-an officially monolingual territory. Participants were administered two widely used psychological tasks: the Flanker Task (a non-language-based task) and the Stroop Task (a language-based task). Three experimental conditions were included in each task: neutral, congruent, and incongruent. Both accuracy and reaction time data were collected and analyzed. The results obtained are consistent between both tasks in showing (i) no detrimental effects of bilingualism; (ii) a high answer accuracy rate; (iii) a practice effect (the more familiar participants became with the tasks the faster their answers became); (iv) sensitivity to an interference effect (higher reaction times for incongruent trials than neutral trials) but not to a clear facilitation effect (lower reaction times for congruent trials than neutral trials). These results, far from being anecdotal, are in line with results from previous research investigating the effects of bilingualism among typically developing individuals as well as non-typically developing individuals with and without genetic disorders. This study not only evidences that Prader-Willi individuals can become bilingual if they are exposed to more than one language, but also that they can do so without showing negative effects at the cognitive level. In fact, taking into account the trend in the descriptive data, if an effect of bilingualism were in place, it would be a positive one. Bilingualism has repetitively been proven to neither be a burden nor to have negative effects for the typically or the non-typically developing population. Thus, as previous researchers have pointed out, there seems to be a clear incongruity between what the research is showing and the actual advice that these individuals and their families are receiving, and this should be amended without further delay.