Predicting executive functions in bilinguals using ecologically valid measures of code-switching behavior

One of the factors claimed to impact on executive functions in bilinguals is code-switching. New insights into how exactly code-switching affects executive functions can be obtained if attention is paid to the kind of code-switching bilinguals engage in, and not just the frequency of code-switching. This raises the question how code-switching habits can be assessed in experimental research. This study presents two ecologically valid, yet efficient, methods of assessing code-switching habits: a frequency judgement task based on authentic stimuli, and a bilingual email production task. The two tasks converged in revealing differences in Dense code-switching in two groups of German-English bilinguals. Moreover, the frequency judgement task predicted code-switching frequency in the ecologically more valid email production task. Importantly, both tasks revealed code-switching patterns that explained group differences observed in executive performance. The bilinguals engaging in frequent Dense code-switching excelled at the aspect of executive functions (conflict-monitoring) predicted to be related to code-switching based on existing processing models. Hence, both methods are recommended for use as code-switching measurements in bilingualism research.