September 24, 2025

Early language development research has found that infants begin with a broad understanding of the physical world and their conceptual knowledge becomes increasingly specialised according to their native language as they grow older. This process is known as perceptual narrowing, whereby during the first year of life, infants undergo developmental changes which reduces their sensitivity to classes of stimuli which they do not encounter in their environment.  

In some languages like Japanese, ground information is encoded within verbs. Japanese ‘ground-path verbs’ incorporate properties of the grounds and the path of motion. For example, the verb ‘wataru’ (go across) describes crossing a bounded surface, like a bridge. In contrast, the more generic ‘tooru’ (go across) refers to crossing an unbounded surface, like a field. In English, ‘to cross’ encompasses both, thus ground information is not encoded within the verb. 

In ‘Sensitivity to visual cues within motion events in monolingual and bilingual infants’ (Journal of Experimental Child Psychology, 2023), Associate Professor Leher Singh (formerly NUS Psychology), Tilbe Göksun (Koç University), Kathy Hirsh-Pasek (Temple University), and Roberta Michnick Golinkoff (University of Delaware) sought to investigate sensitivity to ground-path distinctions in motion events in bilingual children. The researchers found that at 14 months of age, English-learning monolingual infants and English-Mandarin bilingual infants were not sensitive to within-category ground-path distinctions. However, unlike their monolingual counterparts, bilingual infants were also not sensitive to between-category ground-path distinctions at 14 months. At 19 months, bilingual infants diverged from monolingual infants, and were sensitive to both within- and between-category ground-path distinctions. Interestingly, by 24 months, bilingual infants were not sensitive to either between- or within-category ground-path distinctions anymore. 

It is postulated that bilingual infants may take longer than monolingual babies to focus their understanding only on salient contrasts in their native language. Bilingual babies receive more varied exposure from both languages, thus they need more time to figure out which contrasts are salient in their languages. This has been observed in other domains of bilingual language processing as well, and is commonly attributed to the possibility that bilingual infants require more time to consolidate language categories on account of receiving more complex and varied input. 

The researchers suggest that the greater sensitivity to visual contrast observed in bilingual infants may reflect a proclivity to explore and analyse a wider range of stimuli. This increased sensitivity may enable bilingual infants to notice a broader range of contrasts by efficiently disengaging from familiar stimuli. These findings contribute to a growing body of research on the effects of the bilingual experience, presenting the first evidence of an association between the development of language-guided semantic categories and bilingual experience. 

Read the full article here.