1. Introduction

This chapter introduced evidence that bilinguals’ non-target lexicon stays co-activated, yet debate persists over whether L2 is engaged during L1 processing. Behavioral and ERP measures will trace L2 activation time course in L1 semantic and orthographic tasks to clarify mechanisms and resolve conflicting findings.

2. Literature Review

This chapter discussed divergent findings on whether bilinguals’ non-target second language becomes active while they process their dominant first language. Some studies argued that L2 remains dormant when L1 is the target, attributing this to the weaker memory traces of the later-acquired system; behavioral and ERP experiments using interlingual homographs reported null L2 activation in L1 contexts. Others, however, provided electrophysiological evidence that the L2 meaning of homographs does become active, as shown by semantic priming effects on the N400 even when participants judged relatedness solely within L1. These contradictions were traced to methodological constraints: (a) homograph stimuli themselves supply overt cross-linguistic cues, making it hard to determine whether L2 activation is spontaneous or stimulus-driven; (b) task type—semantic versus orthographic—has produced inconsistent outcomes, with some studies observing cross-language effects only under semantic evaluation and others detecting them even in shallow letter-counting tasks; (c) ERP investigations have concentrated almost exclusively on the N400 component, risking oversight of earlier perceptual or later controlled processing signatures of L2 involvement. To overcome these limitations, the present study adopted three corrective measures: an implicit priming design that presented only L1 items, thus removing any direct L2 input; a direct comparison of semantic and orthographic judgment tasks to test task sensitivity; and the simultaneous tracking of P200, N400, and LPC components across early, middle, and late temporal windows to capture any flexible time course of L2 activation.

3. Method

This chapter described the methodological framework for investigating whether non-target English (L2) is activated during Chinese (L1) semantic and orthographic tasks and how this activation unfolds across early (150-250 ms), middle (350-450 ms), and late (500-700 ms) temporal windows. Two independent groups of Chinese-English bilinguals performed distinct L1 tasks to eliminate order and practice effects, thereby safeguarding internal validity. Experiment 1 employed a semantic relatedness judgment on Chinese disyllabic word pairs, whereas Experiment 2 required an orthographic judgment focusing on the count of left-to-right structured characters within the same type of pairs. Stimuli were constructed from high-frequency disyllabic words that, when translated into English, occasionally exhibited alliteration; this phonological overlap in the non-target language served as the critical marker for L2 activation.

Electrophysiological responses were recorded through ERPs at three canonical latencies. P200 (150-250 ms), maximal over centro-frontal and parieto-occipital sites, indexes early sub-lexical processing and is sensitive to both orthographic and phonological similarity; enhanced P200 for English-alliterating Chinese pairs would signal early L2 activation. N400 (350-450 ms), a centro-parietal negativity, reflects semantic integration and phonological priming; reduced N400 for alliterating translations would indicate cross-linguistic phonological resonance. LPC (500-700 ms), a parietal positivity, tracks higher-order re-analysis; differential LPC amplitudes for alliterating versus non-alliterating pairs would reveal late-stage L2 engagement. These components collectively map the time course of covert bilingual lexical access.

Experiment 1 recruited thirty-five unbalanced Chinese-English bilinguals (final N = 31) aged 19-29 years, all right-handed native Mandarin speakers without neurological or visual impairments. Based on a priori power analysis (medium effect, α = .05, 80 % power), the achieved sample exceeded the minimum requirement. Participants reported intermediate English proficiency (OPT M = 34.32, SD = 3.58) and began L2 acquisition on average at age 10. Daily usage heavily favored Chinese, confirming an unbalanced profile. Self-ratings across listening, speaking, reading, and writing corroborated higher L1 than L2 competence, while the OPT objectively anchored proficiency at the intermediate band.

4. Results

This chapter reported ERP and behavioral evidence that bilinguals activate L2 phonology while processing L1. Semantic L1 tasks triggered early P200 and N400 L2 effects, followed by LPC suppression, indicating late inhibition. Orthographic L1 tasks produced sustained P200, N400, and LPC L2 effects, revealing continuous L2 activation when semantic attention is relaxed.

5. Discussion

This chapter discussed the independence of L2 activation from explicit task demands, its variable time course across semantic and orthographic L1 tasks, and the automaticity of early cross-linguistic co-activation indexed by the P200 component. Electrophysiological evidence showed that Chinese-English bilinguals activated English (L2) while processing Chinese (L1), even when the task never required English engagement. The P200 modulation, linked to early orthographic/phonological encoding, and the N400 modulation, linked to semantic integration, jointly revealed that L2 information was accessed within 200 ms and remained available for later stages. Behavioral measures were again blind to these effects, echoing earlier reports that overt performance can miss covert cross-language activity when attention is directed elsewhere.

When the task encouraged semantic analysis of Chinese word pairs (Experiment 1), L2 activation appeared in P200 and N400 windows but disappeared in the LPC window. By contrast, when the task required orthographic judgments about Chinese characters (Experiment 2), L2 activation survived into the LPC. This divergence was attributed to task-specific attentional control. Semantic focus triggers inhibitory control mechanisms that suppress the irrelevant language after initial activation; orthographic focus leaves those mechanisms disengaged, so L2 activation persists. The LPC suppression observed in Experiment 1 aligns with Spanish-English data showing late inhibition of non-target Spanish, corroborating the Inhibitory Control model’s claim that a central control system selectively dampens the language not needed for current goals.

The early P200 findings extend prior work that relied almost exclusively on N400 modulations. Demonstrating reliable L2 effects 200 ms post-stimulus challenges the view that cross-language activation is confined to post-lexical semantic integration. The P200 effect was task-independent, appearing whether participants judged meaning or form, indicating automatic, bottom-up co-activation of both lexicons. This supports non-selective access accounts and underscores that bilingual word recognition is fundamentally language-nonselective from the earliest moments of visual processing.

6. Conclusion

This chapter discussed how bilinguals activate their L2 while processing L1, resolving earlier conflicting findings by tracing the time course of such activation. It showed that task demands—semantic versus orthographic—modulate the magnitude and timing of L2 engagement. Using implicit priming, it demonstrated that L1 stimuli alone can trigger L2 activation, supporting non-selective lexical access. The results imply bidirectional cross-language influence and invite future work on phrase- and syntax-level activation across varied bilingual groups.