An Investigation into Executive Function Differences between Autistic and Non-Autistic Monolinguals and Multilinguals

Background: There has been extensive research to show that multilinguals (those who speak more than one language) enjoy cognitive benefits, such as improved executive function, as a result of their fluency in more than one language (Bialystok, 2010). In contrast, autistic individuals have been documented as having poorer executive function abilities than their neurotypical peers (Hill, 2004). However, relatively little is known about how being multilingual may influence these abilities, The large prevalence of multilingual speakers worldwide and the assumption that autism is a universal condition (i.e. Baxter et al, 2015), would suggest that a large number of multilingual autistic individuals are currently being ignored in research. In addition, families are often advised against raising autistic children as multilinguals, although there is no evidence to support the notion that multilingualism is detrimental to autistic individuals (Jegatheesan et al, 2010; Kremer-Sadlik et al, 2005). This study therefore hopes to highlight that multilingualism is present, and not detrimental to those on the autistic spectrum.

Objectives: This study aimed to examine whether there were differences in executive function performance between autistic multilingual adolescents, autistic monolingual adolescents, and their neurotypical multilingual and monolingual peers.

Methods:The study involved 66 participants, aged 12 to 19, who were administered flanker and set-shifting tasks as part of a battery of executive function measures (NIH Examiner battery, Kramer et al, 2014) and a questionnaire regarding their level of multilingualism. The data from the questionnaire allowed for the creation of four groups of participants, monolingual autistics (N = 18), multilingual autistics (N = 8), monolingual neurotypicals (N = 17) and multilingual neurotypicals (N = 23). Groups were cognitively matched based on their performance on a measure of verbal and non verbal intelligence (from the WASI II, Weshler, 2011) Ethical approval was received from the UCL Institute of Education Ethics Committee.

Results: Mean differences analysis on the two tasks of executive function revealed that on the set-shifting measure, multilingual neurotypical peers performed significantly better than monolingual autistic adolescents (p = 0.009). However, there we no significant differences between the other groups of participants. On the other executive function measure, a flanker task, no significant differences were found. Finally, two regression models measuring the effect of multilingualism and autism on the two executive function scores showed a small, but significant positive effect for set-shifting (r² = 0.113, p = 0.023) but not for the flanker task (r² = 0.088, p = 0.055), though this was approaching significance.

Conclusions: The findings from this study support the notion the multilingualism is not detrimental to autism. They also extend further to suggest there may be some relationship between multilingualism and mental flexibility for both autistic and non-autistic individuals. Further research into this relationship will highlight the full extent of multilingual cognitive benefits autistic individuals may or may not receive, in comparison with their neurotypical peers. Finally, it is hoped that these findings will help inform the choices parents and professionals make when raising and educating a multilingual autistic child.