Will two languages confuse my child?

Not according to King and Mackey, the authors of The Bilingual Edge. They call mixing words from two languages in one sentence a short-term phase for children learning two languages, normal and quite common, and they do not treat it as confusion. The sources read for this site do not measure whether a particular toddler finds two languages tiring, so that part stays open; the last section says so.

What looks like confusion

A young child who puts words from both languages in one sentence is, in King and Mackey's account, still sorting out two language systems and the social rules for which language goes with whom. That takes time, so the mixing is short-lived. It typically fades on its own before school age, without any correction.

A related behaviour in fluent bilinguals points the other way. When adults and older children switch between languages on purpose, King and Mackey say that doing it successfully means the speaker has a detailed grammatical understanding of both languages, and researchers have found it follows systematic rules. The authors call the toddler's version code-mixing and the fluent speaker's version code-switching. Neither is the same as being confused.

Vocabulary can also look like a problem when it is not. King and Mackey say a smaller vocabulary in each language taken separately is normal at an early age and typically closes by school age. In a 1992 study by Pearson, Fernández and Oller, as the book describes it, children learning English only and children learning English and Spanish followed the same vocabulary timetable, and by school age the bilingual children's combined vocabulary matched or exceeded that of their one-language peers. We read the book, not the paper.

What to do tonight

Leave a mixed sentence alone. There is nothing to fix, and the sources say no correction is needed. Answer what your child meant, in the way you normally talk with them. If you want to respond in a way that supports one language, the sources describe five common parent responses. They come from research by Elizabeth Lanza on two Norwegian-American families, as King and Mackey report it:

• Pretend not to understand: "I don't understand, can you say that again?"
• Make a guess in the language you want: "Do you want the ball?"
• Repeat what the child meant in the other language, with no question and no correction.
• Move on and keep the conversation going in whichever language.
• Switch with the child and answer in their language too.

The first two were linked to stronger skills in the language the parent was pushing, especially when one language is weaker. The other three are more bilingual in spirit and do not build the weaker language in the same way. Which one fits depends on what you are trying to do: if you are building the weaker language, the first two are the ones to try. If you are not, any of the five is a choice, not a mistake.

What is still unknown

Your question was whether it is too much for a toddler. No source read for this site tests that. None gives a safe amount of daily exposure to two languages, and none says how to tell a tired or overloaded toddler from a typical one. What the sources do show is narrower: mixing is a normal phase, and in the one study described here children learning two languages kept to the same vocabulary timetable.

The strategy findings come from the authors' account of research on two families. We did not read the study, and the sources describe a link, not proof that a strategy causes stronger skills.

When to ask a professional

If your worry is less about mixing and more about how much your child talks, or about hearing, speech or development, ask your child's pediatrician or a speech-language therapist. The sources read for this site describe mixing as normal; they do not cover how to tell other problems apart.