Is Adult Second Language Acquisition Defective?

Area of Science:

• Linguistics
• Second Language Acquisition
• Psycholinguistics

Background:

• Adult second language (L2) learners often exhibit lower ultimate attainment compared to child learners, leading to the view that adult L2 acquisition is fundamentally different or deficient.
• Previous research often focused on "decorative" grammar (e.g., tense markers) using grammaticality judgment tasks (GST), revealing significant differences between native and L2 speakers.
• However, studies using "functional" grammar tasks (e.g., comprehension of meaning-based contrasts) have shown considerable overlap between native and L2 speakers' performance.

Purpose of the Study:

• To directly compare native speakers, late immersion learners, and classroom foreign language learners on their mastery of both "functional" and "decorative" aspects of grammar.
• To investigate the extent of overlap in grammatical knowledge between native speakers and adult L2 learners across different types of grammatical tasks.
• To re-evaluate the impact of age on L2 acquisition by examining performance on distinct grammatical components.

Main Methods:

• Participants included native speakers, late immersion learners, and classroom foreign language learners.
• Two types of grammatical tasks were administered: one assessing "functional" grammar (meaning-based contrasts) and another assessing "decorative" grammar (grammatical morphemes).
• Performance was evaluated using both spoken and written stimuli to assess potential modality effects.

Main Results:

• Significant differences were observed between native speakers and both non-native groups in "decorative" grammar, especially with spoken stimuli.
• In contrast, performance differences on "functional" grammar tasks were minimal and not statistically significant between native and L2 speakers.
• Greater overlap between native speakers and late L2 learners was found in "decorative" grammar than previously reported, potentially due to underestimation of native speaker variation in earlier studies.

Conclusions:

• Adult L2 learners' attainment in "functional" grammar is comparable to native speakers, challenging the notion of fundamental differences in L2 acquisition based solely on age.
• The distinction between "functional" and "decorative" grammar is crucial for understanding L2 ultimate attainment, with "functional" aspects being more robustly acquired by adult learners.
• Future research should consider the variability within native speaker populations and employ diverse assessment methods to capture a more nuanced picture of L2 proficiency.