The Multilingual Mind: How Does the Brain Choose Which Language to Use?

Anyone who speaks multiple languages has experienced this moment: You try to recall a word but accidentally pull it from the wrong language. Or worse—you start speaking in one language and unconsciously switch to another mid-sentence.

This phenomenon is known as code-switching and language interference in the scientific world.

It happens to me all the time. Since I primarily use English and Chinese throughout my day, I sometimes struggle to recall Turkish words. My brain usually pulls up the English version first, followed by the Chinese equivalent. But things get even more complicated.

For example, when I visit Turkey and answer a phone call, I often unconsciously say “Wei?” (which means “hello” in Chinese) or “Hello?” in English instead of Turkish. Because I’m so used to switching between English and Chinese, my brain makes the transition automatically.

I’ve even had moments where, after speaking in one language, I needed to switch to another—but my first word still came out in the previous language without me realizing it.

When I first moved to Shanghai, my housemates were French, Chinese, Italian, British, American, and Indian. Those who spoke multiple languages would often have a conversation in their native tongue, then walk into another room and accidentally start speaking to me in the same language—only realizing the mistake after seeing my confused expression. That’s when I knew I wasn’t alone in this struggle!

Even when I meet up with friends who speak English-Chinese or English-Turkish fluently, we often mix languages in our conversations.

• Sometimes, this is intentional—using the words we remember most easily makes us feel more comfortable.
• Other times, it happens unintentionally because we’re fluent in both languages and don’t consciously try to stick to just one.

So, why does our brain sometimes mix languages?

Let’s dive into the science behind this fascinating cognitive process! 🚀

What Is Code-Switching, and Why Does It Happen?

Code-switching is the practice of alternating between two or more languages in a single conversation. It’s completely natural and is common among multilingual individuals.

Here’s an example from my own experience:
✅ “Geç kaldım. Shit!” (Translation: “I’m late. Shit!”)

There are several reasons why this happens:

✅ Cognitive Efficiency – The brain selects the most accessible word at the moment. If a word is easier to recall in one language, your brain automatically chooses it.

✅ Contextual Switching – The topic of conversation can trigger a language switch. For example, someone talking about work with their family might accidentally use English terms if they primarily use English in their workplace.

✅ Social & Cultural Influence – People adjust their language based on the person they are speaking to, sometimes resulting in unconscious language mixing.

✅ Cognitive Flexibility – Those who manage multiple languages have stronger cognitive control and can switch between languages more seamlessly.

Essentially, your brain is just trying to communicate as efficiently as possible—even if that means mixing languages!

How Does the Brain Choose Which Language to Use?

Language selection involves multiple brain regions working together:

🧠 Prefrontal Cortex – The brain’s attention and control center, responsible for deciding which language to use and suppressing the wrong one.

🧠 Anterior Cingulate Cortex – The brain’s error detection system, which alerts you when you’ve spoken the wrong language.

🧠 Broca’s Area – The speech production center, which retrieves words and organizes them into sentences.

The brain constantly balances multiple languages, and sometimes, it makes mistakes!

Does Mixing Languages Create Cognitive Overload?

Multilingual speakers’ brains work harder to manage language selection. Studies have shown that bilinguals use more cognitive resources when speaking than monolinguals.

📌 Green (1998) found that multilingual individuals have a more active cognitive control system, which allows them to switch languages efficiently while preventing interference.

📌 Costa et al. (2006) discovered that bilinguals can shift their attention faster and have greater cognitive flexibility than monolinguals.

📌 Mechelli et al. (2004) showed that bilingual individuals have greater gray matter density in their brains, meaning their brains are physically stronger in areas related to language processing!

While multilingual individuals may experience language interference, they also have a stronger cognitive control system and better attention management.

Being Multilingual: A Superpower with Funny Side Effects!

Being bilingual or multilingual can sometimes be confusing, but it’s also an incredible superpower!

Most bilinguals have moments like:
✅ Answering the phone with: “Hello… uhh… Merhaba!”
✅ Catching themselves thinking in the wrong language without realizing it.

But that’s just proof that your brain is a powerful multitasking machine!

Trust Your Brain—It’s Just Choosing the Easiest Path!

Language interference and mixing words is completely normal among multilingual individuals. Your brain is simply trying to find the fastest, most efficient way to communicate.

And honestly? It’s a great sign—it means your brain is highly flexible, strong, and creative!

🚀 So next time you forget which language you’re speaking, don’t stress! It just means your brain is working like a high-speed, multilingual processor!

Want to Speak Fluent English Without Mixing Languages?

If you’re looking to improve your English fluency, check out İDA’s English courses! Whether you want to fix common mistakes, gain confidence, or master pronunciation, you can join today for unlimited access to our lessons.

🌍 See you at İDA—let’s train your multilingual brain together!