Language Control across Comprehension and Production in Unimodal and Bimodal Bilinguals

Unimodal and bimodal bilinguals’ language control mechanisms differ in many ways in both comprehension and production. Unimodal bilinguals process two languages through the same perceptual and motoric systems, whereas bimodal bilinguals engage separate systems for each language. However, little is known about how each group manages language control when comprehension and production intersect, a frequent occurrence in everyday communication such as dialogues. This question is critical, as language control mechanisms in comprehension and production are largely separated. Do bilinguals oscillate between different control mechanisms in daily communication, or do they adaptively adopt a more integrated approach for efficiency? Is it affected by language modalities or experiences? Addressing these issues, the long-term goal of this proposal is to develop a comprehensive understanding of language control across comprehension and production in diverse bilinguals, thus facilitating the development of tailored diagnostic tools, interventions, educational and communication strategies for diverse bilingual children and adults. The proposed project will lay foundation to achieve this goal through comparing unimodal and bimodal bilinguals’ performance when they switch languages from comprehension to production. Through a series of experiments involving alternation between listening/sign comprehension (judgment of words or sentences) and production (picture naming), we will explore how unimodal and bimodal bilinguals address language switching and mixing. These experiments will be conducted in various contexts (e.g., whether production is restricted to one language or can be in both languages), a manipulation based on the framework of adaptive control. In Aim 1, we will investigate unimodal and bimodal bilinguals’ reliance on reactive control by examining language switch costs. In Aim 2, we will investigate their reliance on proactive control by examining language mixing costs and blocked language order effects. This dual focus is critical to a holistic understanding of language control mechanisms, as reactive and production control are two separate processes. Previous research has predominantly concentrated on reactive control, which resolves cross-language interference when it occurs. Proactive control, which operates in anticipation of interference, is underexplored in the comparison between unimodal and bimodal bilinguals. Based on our preliminary results, we hypothesize that unimodal and bimodal bilinguals will adopt reactive control differently across comprehension and production in various contexts but adopt proactive control in a similar fashion. We will also consider how bilinguals’ degree of bilingualism affects the language control mechanisms. The findings of this project will contribute to the development of clinical and educational practices that accommodate the nuanced needs of bilingual individuals, such as tailored communication strategies with unimodal bilingual children and CODAs (Child of Deaf Adults), supporting a broader goal to understanding and facilitating human development in its diversity. Project Number: 1R01HD116841-01A1 | Fiscal Year: 2025 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Chuchu Li | Institution: UNIVERSITY OF CALIFORNIA, SAN DIEGO, LA JOLLA, CA | Award Amount: $363,838 | Activity Code: R01 | Study Section: Language and Communication Study Section[LCOM] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01HD11684101A1