The idea that bilingual children have superior executive function compared to monolingual children has been challenged in recent research. Executive function controls your attention, and helps with such tasks as remembering instructions, controlling responses, and shifting swiftly between tasks. It is positively correlated with children's academic achievement.
However, executive function is a complex construct, with several different components. It has been suggested that inconsistent research findings as to the advantage of bilingualism may be related to differences in how executive function is measured and conceptualized.
A new German study hopes to have dealt with this issues through its methodology and analysis.
The study compared 242 children (aged 5-15) who spoke both Turkish and German, and 95 children who spoke only German. The children’s executive function was tested using a computerized task called Hearts and Flowers, that required the child to press a different key in response to stimuli on the screen, depending on the condition. The congruent condition matched the key to the location of the heart stimulus; the incongruent condition required the child to press the key on the opposite side to where the flower stimulus appeared; the mixed condition tested the ability of the child to use the correct rule depending on which stimulus appeared.
The study found no significant differences in executive function between the two groups, after taking into account maternal education, child gender, age, and working memory (digit span backwards).
The researchers also took into account children's German and Turkish vocabulary size and exposure to both languages, factors for which previous studies on the topic had been criticized for lacking.
Paper available at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209981