Qualitative differences in L3 learners’ neurophysiological response to L1versus L2 transfer

Third language (L3) acquisition differs from first language (L1) and second language (L2) acquisition. There are different views on whether L1 or L2 is of primary influence on L3 acquisition in terms of transfer. This study examines differences in the event-related brain potentials (ERP) response to agreement incongruencies between L1 Spanish speakers and L3 Spanish learners, comparing response differences to incongruencies that are transferrable from the learners’ L1 (Swedish), or their L2 (English). Whereas verb incongruencies, available in L3 learners’ L2 but not their L1, engendered a similar response for L1 speakers and L3 learners, adjective incongruencies, available in L3 learners’ L1 but not their L2, elicited responses that differed between groups: Adjective incongruencies engendered a negativity in the 450-550 ms time window for L1 speakers only. Both congruent and incongruent adjectives also engendered an enhanced P3 wave in L3 learners compared to L1 speakers. Since the P300 correlates with task-related, strategic processing, this indicates that L3 learners process grammatical features that are transferrable from their L1 in a less automatic mode than features that are transferrable from their L2. L3 learners therefore seem to benefit more from their knowledge of their L2 than their knowledge of their L1