Subjective versus objective language proficiency measures in the investigation of bilingual effects on cognitive control.

This article examines whether the use of subjective (self-report) versus objective (performance-based) assessments of language proficiency affects the modeling of bilingual effects on cognitive control. Using data from Mandarin-English bilingual young adults who completed both types of proficiency measures and a Simon task, the study found no evidence that higher second language proficiency improved cognitive control, and importantly, results did not differ between models using subjective or objective proficiency measures. The findings suggest that subjective and objective assessments of language proficiency may be equivalent for investigating bilingual effects on cognitive control, though discrepancies between these measures and cultural factors influencing self-assessment were noted. The study highlights the importance of considering multiple dimensions of bilingual experience and calls for further research across diverse sociolinguistic contexts and developmental stages.