Previous studies have demonstrated that bilinguals have discrete representations for speech sounds that are phonemic in both of their languages. In a lexical identification task for Singapore Mandarin words 椅 (/i2/ ‘chair') and 鱼 (/y2/ ‘fish'), we find steepness of the identification functions differs among bilinguals with different linguistic experience, with steeper slopes for early English-Mandarin bilinguals (for whom the /y/ vowel is phonemic) and shallower slopes for early English-Malay bilinguals (for whom /y/ is not phonemic, but is largely discriminable in the forced choice task). With nuanced language background information, this finding suggests that exposure to both /i/ and /y/ in early development shapes phonemic perception. Model comparisons demonstrate that continuous measures of early exposure are more powerful than simple categorical groupings of bilingual ‘type'. Continuous measures of bilingual exposure are therefore highlighted as useful tools in the investigation of phoneme perception.

English is often discussed with models that have a ‘Centre/Standard’ variety e.g., in US, and UK where English is spoken as a first language, and varieties of spoken elsewhere are regarded as ‘Outer’ or ‘Non-standard’. ‘Standard’ varieties are often regarded as prestigious and worthy of documentation, and to be taught in schools. This is problematic when the speech sounds in the local varieties of English differ from ‘Standard’ varieties. In Singapore, English is the working language among the multilingual population. Despite its importance, speech sounds in Singapore English are not well documented and not used in teaching. 60 Singaporean speakers of English completed a same/different judgement task of 206 words to investigate possible vowel mergers e.g., are ‘sheep/ship’ pronounced the ‘same’? They also read aloud the same words. We analyzed the acoustics (F1, F2) of their articulations and analyzed whether participants’ same/different judgements predicted the way they pronounced the words.

Existing studies have suggested that there may be a link between perception and production of speech sounds. In this paper we examine this link using data collected on Singapore English-Mandarin bilingual adults. We used a 2AFC task to measure perception of the Singapore Mandarin [tsʰuə́n]-[ʈʂʰuə́n] alveolar-retroflex contrast, and measured production using centre of gravity (CoG) measurements on speech recordings of alveolar and retroflex words. We found that a perception-production link may exist in our participants, with participants who exhibit less retroflexion in speech showing less sensitivity to retroflexion in ambiguous speech sounds.

In Singapore, English is the main language at home for 75% of children between 5-9y (2020 Census). The education system has a “English & Mother Tongue” bilingualism policy, and most children grow up hearing two or more languages. Previous examination of vocabulary sizes of Singaporean children showed notably lower scores for age-matched monolingual English-speaking US children. We designed new developmental vocabulary checklists for main languages spoken in Singapore (English, Mandarin, Malay, and Tamil) and Red-Dot, which is a tier of child-directed local words that are not captured in vocabulary inventories adapted from monolingual materials. Many of these local words likely arose from Singapore’s dense contact language environment (e.g., ‘pom pom’ for ‘children’s bathing’). Caregivers of 140 children between 8-40m completed these vocabulary checklists and language input profiles. We analyzed predictive power of language input of caregivers and vocabulary outcomes and growth trajectories of these children.

Bilinguals are reported to have language learning advantages. One possible pathway is a language-specific transfer effect, whereby sensitivity to structural regularities in known languages can be brought to novel languages that share features. To test for specific linguistic feature transfer, we designed a task for bilinguals with homogeneous language exposure (bilingual in same languages) and heterogeneous feature representation (differing proficiencies). As Hindi and Mandarin have retroflexion in phoneme contrasts, we conducted a pre-registered study with a statistical learning task of a Hindi dental-retroflex contrast on parallel English-Mandarin bilinguals with varied Mandarin proficiency. Unlike the pilot study (N = 15), the main study (N = 50) found no evidence for a learning effect, and language-experience did not explain learning variance. As these stimuli have shown learning effects in children, learning effects for this feature may be fragile in this adult population, and language-specific neural commitments may prevent learning of the contrast.

Chinese phonology features a contrast between alveolar and retroflex places of articulation, particularly in the standard Beijing variety of Mandarin. However, studies have shown that ‘outer-circle’ varieties (such as in Taiwan and Singapore) have a less clear contrast, termed “deretroflexion”, which results in poor contrastive perception for Taiwan Mandarin speakers. However, our previous study did not find this deficit in Singapore Mandarin speakers. In this preregistered follow-up study, we investigate how Singapore Mandarin speakers perceive the alveolar-retroflex contrast and examine if differences in perception are linked to Mandarin understanding proficiency. Our results (N = 62) reveal that while Singapore Mandarin speakers perceive an alveolar-retroflex phoneme contrast, there is a wide range of differences in ambiguity resolution across the alveolar-retroflex acoustic spectrum. We did not find a link between perceptual differences and Mandarin understanding proficiency, indicating that highly ‘tuned’ perceptual sensitivity is not needed for high Mandarin understanding proficiency.

Language-specific accounts of bilingual learning advantages suggest that advantages in language learning are tied to an individual's linguistic experience, with learning advantages stemming from transfer effects between known and to-be-learnt language features. To test this hypothesis, we trained Singapore English-Mandarin bilinguals on a synthesised alveolar-retroflex [ts ∞u…ôÃÅn]-[ à Ç ∞u…ôÃÅn] contrast with a bimodal distributional learning paradigm. We reasoned that participants with higher Mandarin understanding proficiencies would show larger distributional learning effects due to transfer between real-world Mandarin experience and the training stimuli. We examined overall learning effects in a pilot study (N = 20) and a preregistered main study (N = 50). We found evidence of learning in both the pilot and the main study. We also found evidence of a transfer effect tied to individual Mandarin skills, with larger learning effects linked to higher Mandarin understanding proficiencies. This study demonstrates specific advantages of language background on perceptual learning at the individual level.

Adults and children systematically match certain kinds of words to certain kinds of shapes according to the sounds of their phonemes (e.g., ‘kiki’-spiky ‘bouba’-curvy). These sound-shape mappings rely on multisensory processing of perceived goodness of fit between vision and audition. Dyslexic individuals have shown deficits in general multisensory processing and sound-symbolic matching suggesting that multisensory processing deficits may be developmentally implicated in early reading difficulties. A longitudinal cohort study tracking bilingual children in Singapore showed that early predictors of English reading at 4 years (e.g., phonological awareness, vocabulary size and letter knowledge) did not correlate with a novel child-friendly task eliciting the bouba-kiki effect at 6 years. However, since the children had not yet started formal reading instruction, it is difficult to interpret the lack of relationship. In the current study, we followed the same cohort of children into early reading years and tested their English word and pseudoword reading abilities at 8.5 years. In our preregistered analysis, no significant relationship was observed between earlier multisensory sound-shape matching reading outcomes but known predictors of reading showed strong relationships in this cohort of bilingual children.

Recent studies suggest that multisensory linkages betweenspeech and vision are implicated in the development ofdyslexia. Current data only address a relationship in adultswith existing diagnoses, but do not inform us about thedevelopmental trajectory of the association. We conducted apre-registered study of multisensory matching in 388 pre-readers in Singapore (Age: 5y 10m) using an adaptation of thebouba-kiki task (the Alien Zoo), and compared children’sperformance on this task to their earlier scores on measuresknown to predict dyslexia: phonological awareness,vocabulary size and letter knowledge. As reported elsewhere,children’s Alien Zoo scores were lower than adults’(Woon &Styles, 2017a). The language measures were strongly inter-correlated, suggesting persistent language skills acrossmultiple domains, However we found no significantrelationship between performance on the Alien Zoo task andany of the predictors of dyslexia. This may mean that therelationship is yet to emerge in this population. The childrenin this cohort will be tracked and tested at a later time point toestablish the developmental trajectory of this relationship.