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How multilingualism shapes word learning

This article explores a core aspect of linguistic development, word learning. The mapping of a sequence of sounds (phonemes) to a meaning.
© University of Reading

One core aspect of linguistic development is word learning – the mapping of a sequence of sounds (phonemes) to a meaning. For example, making the connection between the sequence of the phonemes /d/ /ɒ/ /g/ and the animal, ‘dog’. While words can map onto a range of different concepts, the vast majority of word learning research in infants and young children has focused on the learning of concrete nouns and, to a lesser extent, verbs.

Walking dog by Carsten Tolkmit CC BY-SA 2.0.

Mutual exclusivity bias

Word learning is a complex task and research has shown that it is shaped by several constraints and biases that determine children’s strategies. One of these is the mutual exclusivity bias: when encountering a novel word (eg, dax) in the presence of a familiar object (ball) and a novel object, children will tend to assume that the novel word refers to the novel object1.

Beach ball by red11group CC BY-SA 2.0 and Cocktail Strainer by MyName (Melikamp), CC BY-SA 3.0, via Wikimedia Commons

Of course, this strategy has limitations because there can be multiple words that label the same thing. For example, a dog is also an animal, a pet, or a Golden Retriever. However, children’s initial priority is to learn labels for as many different concepts as possible in the world around them, rather than many different labels for the same thing. Or at least, this is what researchers thought when they only included monolingual children in their studies2. Monolingual children show a mutual exclusivity bias which grows stronger as they gain experience in learning language or, to put it another way, children with larger vocabularies are more likely to show a mutual exclusivity effect. It is thought that children who know more words also have stronger one-to-one word-object mappings. In turn, more robust form-meaning mappings for familiar words (eg, ball) will make them more certain in their choice of the novel object for the novel word, as the familiar object already has a well-established label.

Children who are learning two or more languages will need to do this word-object mapping for all of their languages. As they do so they will need to override mutual exclusivity as the same object can indeed be mapped to more than one word (across the different languages).

photo of dog walking on beach with text: = /dɒg/ (English) /cane/ (Italian)

Studies comparing mutual exclusivity effects in monolingual and multilingual children have reported mixed findings. Although some studies have found no differences between monolingual and multilingual children, overall bilingual and trilingual children are more likely than monolinguals of the same age to accept a novel label for a familiar object3. And even in studies where there were no differences between monolinguals and bilinguals, when re-tested on the same familiar-novel object pairings, bilinguals were less likely than monolinguals to remember that the new label referred to the new object. It appears that, at least in the early stages of acquisition, bilingual children have a preference towards the accumulation of Translation Equivalents (TEs), or cross-language synonyms (eg, dog-cane).

Translation Equivalents and multilingual word learning strategies

TEs are key to understanding multilingual children’s word learning strategies and the degree to which the two languages interact or are kept relatively separate.

In principle there are three possible scenarios:

  • children could avoid TEs and focus on words that are unique to each language (singlets)
  • they could prefer TEs, or
  • they could learn both TEs and singlets at the same rate.

The approach children take depends on the size of their vocabulary and on the opportunity to learn TEs in the first place. Because TEs are labels for the same concept across two languages, the number of words in each language determines the possible number of TE pairs. Another constraint is the conceptual difficulty of a word. So, for a two-year-old, it will be easier to acquire TEs for developmentally early nouns like ‘dog’ and ‘ball’ than to learn a singlet like ‘motorway’ which is not an early-acquired word.

multicoloured beach ball dog cat
Ball / Pelota Dog / Perro Cat / Gato
One-to-many object-word mapping (eg, English/Spanish)

Recent studies4 considered the overall vocabulary size across languages and the conceptual difficulties of words and explored the role of TEs in word learning. They found that when children are younger they find it easier to learn a new word in a language if they already know it in another language. This lessens after about two years of age, after which they can learn new words without having to rely on TEs. Over time, children who have grown up with two or more languages become better able to treat each of their languages relatively separately. For children who are learning a second or third language after a first language is already well established, the existence of a mapping between concept and word can be exploited for vocabulary learning in the new language.


  1. Markman, E. M., & Wachtel, G. F. (1988). Children’s use of mutual exclusivity to constrain the meanings of words. Cognitive Psychology, 20(2), 121-157.
  2. Houston‐Price, C., Caloghiris, Z., & Raviglione, E. (2010). Language experience shapes the development of the mutual exclusivity bias. Infancy, 15(2), 125-150.
  3. Byers‐Heinlein, K., & Werker, J. F. (2009). Monolingual, bilingual, trilingual: Infants’ language experience influences the development of a word‐learning heuristic. Developmental science, 12(5), 815-823.
  4. Tsui, R. K. Y., Gonzalez-Barrero, A. M., Schott, E., & Byers-Heinlein, K. (2022). Are translation equivalents special? Evidence from simulations and empirical data from bilingual infants. Cognition, 225, 105084.
© University of Reading
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Understanding Multilingual Children's Language Development

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