Automaticity of speech processing in early bilingual adults and children

Area of Science:

• Neuroscience
• Linguistics
• Psychology

Background:

• Early second language (L2) acquisition's impact on neural processing of phonemic contrasts is not fully understood.
• Investigating how bilingualism affects the brain's ability to distinguish sounds not present in the native language (L1).

Purpose of the Study:

• To determine if early L2 acquisition results in native-like neural processing of phonemic contrasts.
• To compare neural responses to English /I/ - /ε/ contrast in monolingual and early bilingual adults and children.

Main Methods:

• Used electroencephalography (EEG) to measure neural responses: Mismatch Negativity (MMN) for automatic change detection, and Processing Negativity (PN) & Late Negativity (LN) for attention.
• Compared four groups: adult/child English monolinguals and adult/child early bilinguals (English/Spanish, exposed before age 5).
• Varied participant attention to the stimulus stream during MMN, PN, and LN measurements.

Main Results:

• Bilingualism did not affect Mismatch Negativity (MMN) responses, indicating no difference in automatic change detection.
• Adult bilinguals showed significant differences in attention-related neural indices (PN, LN) compared to adult monolinguals.
• Child bilinguals' neural responses were indistinguishable from their monolingual peers.

Conclusions:

• Early second language acquisition (before age 5) leads to native-like phoneme discrimination.
• Bilingualism enhances attentional sensitivity to speech sounds, particularly in adults.
• Neural processing of speech sounds is shaped by early bilingual experience and attentional demands.