Are executive functions among Javanese and Sundanese affected by language spoken at home and in public?

The need for standardized neuropsychological tests, scoring, and interpretation is crucial for distinguishing individuals with normal cognitive function from those with deficits. Executive function (EF) is one of four cognitive domains assessed by the Indonesian Neuropsychological Test Battery (INTB), which is administered exclusively in Bahasa Indonesia. Given Indonesia's ethnic and linguistic diversity, ensuring equal validity of EF tests across groups is essential. This study examined potential ethnic differences between the Javanese and Sundanese, Indonesia's two largest ethnic groups, and the influence of languages spoken at home and in public on performance in five EF tests: digit span, five-point, trail making, verbal fluency, and Stroop. A total of 147 healthy participants, matched for age and education, were assessed. Results revealed minimal performance differences between ethnicities. However, language spoken at home significantly affected scores across all tests for both groups. Participants who did not speak Bahasa Indonesia at home showed disadvantages, while bilinguals demonstrated advantages on the Stroop test. The findings show that home language influences EF test outcomes and that bilingualism confers benefits. Hence, language spoken at home constitutes a key demographic factor affecting EF performance alongside age and education.