Modulatory role of inhibition during language switching: Evidence from evoked and induced oscillatory activity

Abstract

Aims:

The present study adopted the electroencephalogram (EEG) technique to investigate whether inhibition advantage could modulate different language switches, regardless of the time spent on second language learning.

Design:

The inhibitory control (IC) ability of 80 low-proficient Chinese (L1)-English (L2) bilinguals was assessed by the Simon task. Half of these bilinguals were then subdivided into 20 high- and 20 low-IC participants to perform switching between L1 and L2 (L1–L2 switching), and the other half were subdivided into 20 high- and 20 low-IC participants to conduct switching between L1 and Lnew (L1–Lnew switching). All participants were required to name pictures (picture naming task) in their L1 and L2/Lnew in language switching task.

Data and analysis:

Both response latencies and EEG data were obtained, and then evoked and induced oscillations were calculated using time–frequency analysis.

Findings:

The results of language switching showed similar naming latencies for L1 and L2/Lnew switch trials in the high-IC group, whereas the low-IC group showed larger naming latencies for L1 switch trials than L2/Lnew switch trials. In contrast, the high-IC group exhibited larger theta evoked and induced power for L2/Lnew switch trials than L1 switch trials at the lexical selection level, whereas the low-IC group did not. These findings indicate that inhibition advantage helps the high-IC group to suppress effectively the non-target word via recruiting bottom-up (evoked oscillation) and top-down (induced oscillation) processes.

Innovation:

The present study was a first attempt to provide evidence that theta oscillation indicates cross-language interference at the lexical selection level.

Significance:

Inhibition plays a modulatory role in language switching, which is independent of the time spent on second language learning, and such role involves bottom-up (i.e., evoked oscillation) and top-down (i.e., induced oscillation) processes which were mainly evident at the lexical selection level.