Codas as Bimodal Bilinguals

Imagine growing up with a “superpower” that lets you fluently navigate two distinct worlds, each with its own language, culture, and way of thinking. For Codas (Children of Deaf Adults), being bimodal bilinguals—able to communicate in both a spoken and a signed language—is exactly that! This incredible skill opens up unique cognitive abilities and enhances mental flexibility, granting Codas a special edge.

Bimodal bilingualism gives Codas the ability to switch seamlessly between spoken and visual-spatial languages, processing each in separate pathways in the brain. This flexibility enables them to manage tasks that others might find overwhelming, such as interpreting across languages simultaneously or multitasking in different modalities. In essence, their brains are like finely-tuned machines, able to handle spoken and signed languages without the interference or competition typical for traditional bilinguals. Let’s dive into what makes this superpower so exceptional, exploring the distinct cognitive and neural characteristics of bimodal bilinguals compared to traditional bilinguals and uncovering the amazing potential of the Coda mind.

Different Neural Pathways for Processing Modalities

• Bimodal Brain Structure: Bimodal bilinguals use separate brain networks for their spoken and signed languages. Spoken languages are typically processed in auditory regions, while signed languages activate visual-spatial processing areas in the brain, particularly in the parietal and occipital lobes (Emmorey et al., 2016).
• Contrast with Unimodal Bilinguals: Traditional bilinguals who speak two languages use overlapping brain regions, particularly in the left hemisphere’s language centers (such as Broca’s and Wernicke’s areas), for both languages. This overlap can lead to greater competition between languages and more reliance on inhibitory control to prevent interference.
• Impact on Cognitive Processing: Because bimodal bilinguals use different pathways for each language, they can sometimes process both languages simultaneously with less interference, reducing the cognitive load associated with switching between languages (Emmorey et al., 2008). This can enhance their ability to multitask and reduces the need for inhibitory control when switching between modalities.

Simultaneous Bimodal Language Production

• Bimodal Capacity for Dual Output: Bimodal bilinguals have the unique ability to produce spoken and signed language at the same time, a phenomenon known as “simultaneous communication.” For instance, they may speak English while signing in American Sign Language (ASL), effectively expressing two languages at once.
• Contrast with Unimodal Bilinguals: Unimodal bilinguals can only speak one language at a time, as both languages rely on the same modality (auditory and verbal). Attempting to use both languages simultaneously would cause confusion and interference due to overlapping motor and auditory demands.
• Impact on Cognitive Flexibility: This ability for dual output in bimodal bilinguals enhances cognitive flexibility and may improve mental switching between tasks. However, it can also demand more working memory and attention, especially when each language conveys slightly different information or syntax.

Reduced Competition and Interference Between Languages

• Bimodal Language Separation: Because the spoken and signed languages are processed through separate channels (auditory vs. visual), they interfere less with each other than two spoken languages would. This separation allows bimodal bilinguals to switch languages without experiencing as much cognitive interference, which is common in unimodal bilinguals who need to inhibit one spoken language to use another.
• Contrast with Unimodal Bilinguals: Unimodal bilinguals experience more competition between languages due to shared processing areas, requiring stronger inhibitory control to suppress one language when speaking in the other (Green, 1998).
• Impact on Brain Development: The reduced need for inhibition in bimodal bilinguals may mean they develop slightly different cognitive control mechanisms compared to unimodal bilinguals. Studies suggest that bimodal bilinguals have unique strengths in cognitive flexibility and visual-spatial processing rather than the strong inhibitory control typically observed in unimodal bilinguals (Macnamara & Conway, 2014).

Enhanced Visual-Spatial Skills

• Visual-Spatial Demands of Signed Language: Signed languages require strong visual-spatial skills, as they involve complex spatial structuring, facial expressions, and hand movements. This can enhance areas of the brain responsible for spatial processing and visual attention, such as the parietal lobe.
• Contrast with Unimodal Bilinguals: Unimodal bilinguals typically don’t experience the same visual-spatial demands, as spoken languages primarily engage auditory and verbal processing.
• Impact on Cognitive Abilities: Bimodal bilinguals often exhibit enhanced visual-spatial memory and visual attention. These skills are not only useful for communication in sign language but can also benefit other areas requiring spatial awareness and attention, such as navigation and certain forms of problem-solving (Bavelier et al., 2008).

Distinct Working Memory Demands

• Working Memory in Bimodal Bilinguals: Bimodal bilingualism places unique demands on working memory because it requires holding and processing two different types of information (visual and auditory) simultaneously. This may lead to enhanced working memory skills for visual tasks but also require a higher capacity for managing multiple types of information in real-time.
• Contrast with Unimodal Bilinguals: Unimodal bilinguals use working memory within a single modality, typically handling only auditory-verbal input. While they develop strong verbal working memory, they don’t necessarily have the same visual-spatial working memory strengths seen in bimodal bilinguals.
• Impact on Cognitive Skills: The ability to hold and integrate visual and auditory information may give bimodal bilinguals a cognitive edge in tasks that involve multi-modal integration or visual memory tasks. However, this demand can also lead to mental fatigue faster than unimodal bilinguals in situations requiring continuous, simultaneous processing across modalities (Morford et al., 2011).

Potential for Enhanced Multitasking Abilities

• Multitasking with Dual Modalities: Bimodal bilinguals are often adept at multitasking because they can manage visual and auditory tasks in parallel. For example, they can carry on a spoken conversation while signing or interpreting visual cues, effectively processing dual inputs.
• Contrast with Unimodal Bilinguals: Unimodal bilinguals face greater challenges when multitasking because both languages are processed within the same modality, leading to more direct competition for cognitive resources.
• Impact on Cognitive Processing: The ability to multitask across modalities may make bimodal bilinguals particularly skilled at tasks requiring divided attention and mental flexibility. However, this can also increase cognitive load, especially in high-stress or complex scenarios where simultaneous processing becomes demanding.

Neuroplasticity and Brain Adaptation Differences

• Neuroplasticity in Bimodal Bilinguals: Bimodal bilinguals show unique brain adaptations, such as stronger connections between visual and language processing areas, due to their experience using two distinct modalities. This cross-modal neuroplasticity is not typically observed in unimodal bilinguals (MacSweeney et al., 2008).
• Contrast with Unimodal Bilinguals: Unimodal bilinguals may develop increased gray matter density in language-specific areas, like the left inferior parietal cortex, but do not usually show the same cross-modal adaptations seen in bimodal bilinguals.
• Impact on Learning and Cognitive Processing: These neuroplastic changes in bimodal bilinguals may support better integration of visual and auditory information, which can aid in learning and processing in various contexts. The cross-modal connections also suggest that bimodal bilinguals may be more adaptable in situations that require sensory integration.

Summary: Differences and Implications for Bimodal Bilinguals

In summary, bimodal bilinguals exhibit distinct cognitive and neural characteristics compared to traditional, unimodal bilinguals. The use of two separate modalities (spoken and signed) leads to:

• Less interference and competition between languages due to separate processing channels.
• Enhanced cognitive flexibility and multitasking skills due to the ability to manage dual output (spoken and signed) simultaneously.
• Stronger visual-spatial skills and adaptations in visual attention and memory due to the demands of sign language.
• Unique neuroplasticity that integrates auditory and visual processing areas, fostering cross-modal cognitive strengths.

These differences suggest that bimodal bilinguals have a unique cognitive profile, with specific strengths in multitasking, visual-spatial processing, and flexibility in managing different types of input. However, the added demands of processing across modalities can also create unique challenges, such as increased cognitive load and potential for mental fatigue, especially in high-demand situations that require simultaneous processing.

References

• Emmorey, K., Giezen, M. R., & Gollan, T. H. (2016). Psycholinguistic, cognitive, and neural implications of bimodal bilingualism. Bilingualism: Language and Cognition, 19(2), 223–242.
• Emmorey, K., Luk, G., Pyers, J. E., & Bialystok, E. (2008). The source of enhanced cognitive control in bilinguals: Evidence from bimodal bilinguals. Psychological Science, 19(12), 1201–1206.
• Bavelier, D., Dye, M. W., & Hauser, P. C. (2008). Do deaf individuals see better? Trends in Cognitive Sciences, 10(11), 512–518.
• MacSweeney, M., Capek, C. M., Campbell, R., & Woll, B. (2008). The signing brain: The neurobiology of sign language. Trends in Cognitive Sciences, 12(11), 432–440.
• Morford, J. P., Wilkinson, E., Villwock, A., Piñar, P., & Kroll, J. F. (2011). When deaf signers read English: Do written words activate their sign translations? Cognition, 118(3), 286–292.
• Green, D. W. (1998). Mental control of the bilingual lexico-semantic system. Bilingualism: Language and Cognition, 1(2), 67–81.