11:51pm Monday 06 July 2020

Bilingual infants read lips at an earlier age and for a longer time than monolingual

A group of researchers at the University of Barcelona (UB) has identified one of the strategies they use to learn two languages at the same time without finding any extra difficulty, apparently. According to the study, published in the journal Psychological Science, bilingual infants look at speaker’s mouth at an earlier stage and for a longer time than monolingual infants. This mechanism seems to be crucial in order to differentiate between two languages and facilitate language learning.

The study is signed by Ferran Pons and Laura Bosch, lecturers in the Department of Basic Psychology at the Faculty of Psychology of the UB and the Institute for Brain, Cognition and Behaviour (IR3C), and David J. Lewkowicz, from the Northeastern University (Boston, USA).

Existing evidence indicates that inferring visual information from the mouth helps to understand speakers’ utterances. Therefore, infants learn to speak not only by listening to sounds, but also by reading lips. As infants begin to babble (at around 8 months), they start looking more at the mouth of the speaker to profit the great amount of information they get by observing speaker’s lips.

To profit audiovisual speech cues

Considering previous studies, the UB research group tested their predictions by examining one group of monolingual infants and one group of bilingual (Catalan and Spanish) infants. In the experiments, babies had to watch a video in which one woman speaks in Catalan or Spanish. Infants wore an eye tracker apparatus that enabled to measure accurately how much time they looked at the eyes and the mouth of the speaker. The objective was to find differences between how monolingual and bilingual babies profit audiovisual speech cues.
Study results prove that bilingual infants look at the mouth at an earlier stage and for a longer time than monolingual infants. “We knew that monolingual babies look at the mouth during babbling; however, the study first shows that bilingual babies need visual information to differentiate between the two languages used in their environment”, affirms Ferran Pons.

Researchers found that 4-month monolingual infants look more at the eyes than at the mouth, while 4-month bilingual infants look equally at the eyes and the mouth, independently of the language spoken in the video. “To support their dual language acquisition, bilingual babies exploit audiovisual speech cues at an earlier age (four months) than monolingual babies who do not need to do it”, explains Ferran Pons.

A tool to consolidate language learning

The experiment also shows that this trend continues in 12-month infants. On the one hand, monolingual infants look equally at the eyes and the mouth at 12 months in response to native speech, but they look for a longer time at the mouth in response to non-native speech. On the other hand, bilingual infants look for a longer time at the mouth, independently of the language, “In the case of older infants, bilinguals continue using this visual information as they are consolidating their two mother tongues”, points out Ferran Pons.

The study was combined with other investigation that compares learning strategies used by bilingual infants who learn similar Romance languages (Catalan and Spanish) with the strategies applied by learners of two distant languages (Spanish and English). The first results obtained in the study, carried out with infants at 12 and 15 moths, suggest that it is more difficult to learn two similar languages. Bilingual infants learning two similar languages need to look more at the mouth than those learning two languages which are not similar. “In other words, the more complex is the language environment that surrounds children, the more they need to use audiovisual speech cues”, emphasizes the researcher.

Advantages to deal with language disorders

The study provides new insight into the different factors involved in language learning difficulties in early development stages. Moreover, it has also initiated a new research line that relates the action of looking at the eyes or the mouth not only to language learning but also to communicative, social and emotional variables. “We try to explore all the factors intervening in the patterns of selective attention used by an infant when he or she interacts with an adult and to determine to what extent aspect such as the fact of being bilingual can shape this pattern without indicating any social or communicative problem”, concludes the researcher.

Article reference:

Pons, F.; Bosch, L.; Lewkowicz, D. J. “Bilingualism Modulates Infants’ Selective Attention to the Mouth of a Talking Face“. Psychological Science Online, 2015. DOI: 10.1177/0956797614568320

Universitat de Barcelona

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