Abstract: This study used the ERP (event-related potential) technique to investigate the number attraction effect in L2 agreement processing and its individual differences. Experiment results showed that advanced EFL learners exhibited distinct ERP patterns in different local noun conditions: ungrammatical verbs following singular local nouns elicited a P600 effect relative to their grammatical counterparts, whereas this positivity was replaced by an N400 effect when plural local nouns intervened between the subject head nouns and the verbs. Moreover, advanced EFL learners showed an asymmetrical pattern of attraction effect, in that plural local nouns interfered with the processing of ungrammatical sentences rather than grammatical sentences. Lastly, individual difference analyses revealed that EFL learners exhibited a pattern of N400~P600 continuum, with the number of P600-effect dominant participants being larger than that of N400-effect dominant participants in the singular local noun condition, but the number of N400-effect dominant participants larger than that of P600-effect dominant participants in the plural local noun condition. The overall outcome demonstrated that advanced EFL learners are sensitive to the attraction effect. Moreover, individual differences in the L2 number attraction effect implies that L2 syntactic processing is not restricted to a parsing route of a particular kind.
Key words: subject-verb agreement; number attraction; cue-base memory retrieval model; individual difference; ERP