Research on the cognitive neural mechanisms of language control often overlooks the role of rewards. To investigate how reversal rewards affect bilingual language switching during observational learning, we conducted a dual-brain electroencephalography (EEG) study. Participants, classified as direct learners or observers, performed a voluntary language-switching task under dynamic reward conditions. Our results demonstrated that both direct learners and observers exhibited high correct acquisition rates for the switch and non-switch behaviors in both pre- and post-reversal phases. Notably, direct learners and observers showed reduced switch costs in the post-reversal phase, highlighting enhanced language control efficiency. EEG analyses revealed that direct learners exhibited late positive component (LPC) switch costs in both pre- and post-reversal phases, while observers showed LPC switch costs only in the post-reversal phase. These findings support the Adaptive Control Hypothesis by highlighting the adaptability of language control mechanisms in response to dynamic reward environments during direct and observational learning.

Compound words consist of two or more words which combine to form a single word or phrase that acts as one. In English, the head of compound words is usually, but not always, the right-most root (e.g., “paycheck” is a noun because the head, “check,” is a noun). The current study explores the effects of head position on language control by examining language switching performance through electroencephalography (EEG). Twenty-one pairs of Chinese (L1)–English (L2) bilinguals performed cued language switching in a simultaneous production and comprehension task. The results showed that bilinguals recognized the head position earlier both in production and comprehension. However, the language control of the head position during production occurred in the middle stage (N2), but in the late stage (LPC) during comprehension. These findings indicate that the head position in compound words exerts differential influences on language control.

When bilinguals switch between their two languages, they often alternate between words whose formation rules in one language are different from the other (e.g., a noun-verb compound in one language may be a verb-noun compound in another language). In this study, we analyze behavioral performance and electrophysiological activity to examine the effects of morphological configuration on language control during production and comprehension. Chinese–English bilinguals completed a joint naming-listening task involving cued language switching. The findings showed differential effects of morphological configuration on language production and comprehension. In production, morphological configuration was processed sequentially, suggesting that bilingual production may be a combination of sequential processing and inhibition of morphological levels and language interference. In comprehension, however, bottom-up control processes appear to mask the influence of sequential processing on language switching. Together, these findings underscore differential functionalities of language control in speaking and listening.

C-doped, Mo-doped, and (Mo, C)-codoped TiO2 photocatalysts were prepared by a sol-gel process. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange (MO) under simulated solar irradiation. Results indicated that both monodoped and codoped TiO2 exhibited better visible light absorption behavior and narrower energy gap than pure TiO2, and codoped TiO2 showed a slightly higher adsorption property in the dark because of higher Brunauer–Emmett–Teller-specific surface area. The photocatalytic activity of monodoped TiO2 was also enhanced, and the (0.04% Mo, C)-codoped sample had the best photocatalytic activity for degrading MO among all of the samples. The reason can be ascribed to the synergistic effect due to Mo and C doping. Furthermore, the transfer pathways of photoinduced carriers and photocatalytic reaction mechanism of (Mo, C)-codoped TiO2 was first investigated.