The sooner the better? An investigation into the role of age of onset and its relation with transfer and exposure in bilingual Frisian-Dutch children

In this study, age of onset (AoO) was investigated in five- and six-yearold
bilingual Frisian–Dutch children. AoO to Dutch ranged between
zero and four and had a positive effect on Dutch receptive vocabulary
size, but hardly influenced the children’s accurate use of Dutch
inflection. The influence of AoO on vocabulary was more prominent
than the influence of exposure. Regarding inflection, the reverse was
found. Accuracy at using Frisian inflection emerged as a significant
predictor; this transfer effect was modulated by lexical overlap
between the two languages. This study shows that ‘the sooner the
better’ does not necessarily hold for language development. In fact,
for the correct use of inflection, it does not matter whether children
start at age zero or four. For rapidly learning words in a new language
it may be helpful to first build a substantial vocabulary in the first
language before learning a new language.