Variation in phonological bias: Bias for vowels, rather than consonants or tones in lexical processing by Cantonese-learning toddlers

Tonal interference in word learning? A comparison of Cantonese and French

Most languages of the world use lexical tones to contrast words. Thus, understanding how individuals process tones when learning new words is fundamental for a better understanding of the mechanisms underlying word learning. The current study asked how tonal information is integrated during word learning. We investigated whether variability in tonal information during learning can interfere with the learning of new words and whether this is language and age dependent. Cantonese- and French-learning 30-month-olds (N = 97) and Cantonese- and French-speaking adults (N = 50) were tested with an eye-tracking task on their ability to learn phonetically different pairs of novel words in two learning conditions: a 1-tone condition in which each object was named with a single label and a 3-tone condition in which each object was named with three different labels varying in tone. We predicted learning in all groups in the 1-tone condition. For the 3-tone condition, because tones are part of the phonological system of Cantonese but not of French, we expected the Cantonese groups to either fail (toddlers) or show lower performance than in the 1-tone condition (adults), whereas the French groups might show less sensitivity to this manipulation. The results show that all participants learned in the 1-tone condition and were sensitive to tone variation to some extent. Learning in the 3-tone condition was impeded in both groups of toddlers. We argue that tonal interference in word learning likely comes from the phonological level in the Cantonese groups and from the acoustic level in the French groups.

The development of tone discrimination in infancy: Evidence from a cross-linguistic, multi-lab report

We report the findings of a multi-language and multi-lab investigation of young infants' ability to discriminate lexical tones as a function of their native language, age and language experience, as well as of tone properties. Given the high prevalence of lexical tones across human languages, understanding lexical tone acquisition is fundamental for comprehensive theories of language learning. While there are some similarities between the developmental course of lexical tone perception and that of vowels and consonants, findings for lexical tones tend to vary greatly across different laboratories. To reconcile these differences and to assess the developmental trajectory of native and non-native perception of tone contrasts, this study employed a single experimental paradigm with the same two pairs of Cantonese tone contrasts (perceptually similar vs. distinct) across 13 laboratories in Asia-Pacific, Europe and North-America testing 5-, 10- and 17-month-old monolingual (tone, pitch-accent, non-tone) and bilingual (tone/non-tone, non-tone/non-tone) infants. Across the age range and language backgrounds, infants who were not exposed to Cantonese showed robust discrimination of the two non-native lexical tone contrasts. Contrary to this overall finding, the statistical model assessing native discrimination by Cantonese-learning infants failed to yield significant effects. These findings indicate that lexical tone sensitivity is maintained from 5 to 17 months in infants acquiring tone and non-tone languages, challenging the generalisability of the existing theoretical accounts of perceptual narrowing in the first months of life. RESEARCH HIGHLIGHTS: This is a multi-language and multi-lab investigation of young infants' ability to discriminate lexical tones. This study included data from 13 laboratories testing 5-, 10-, and 17-month-old monolingual (tone, pitch-accent, non-tone) and bilingual (tone/non-tone, non-tone/non-tone) infants. Overall, infants discriminated a perceptually similar and a distinct non-native tone contrast, although there was no evidence of a native tone-language advantage in discrimination. These results demonstrate maintenance of tone discrimination throughout development.

The influence of language-specific properties on the role of consonants and vowels in a statistical learning task of an artificial language: A cross-linguistic comparison

The contribution of consonants and vowels in spoken word processing has been widely investigated, and studies have found a phenomenon of a Consonantal bias (C-bias), indicating that consonants carry more weight than vowels. However, across languages, various patterns have been documented, including that of no preference or a reverse pattern of Vowel bias. A central question is how the manifestation of the C-bias is modulated by language-specific factors. This question can be addressed by cross-linguistic studies. Comparing native Hebrew and native English speakers, this study examines the relative importance of transitional probabilities between non-adjacent consonants as opposed to vowels during auditory statistical learning (SL) of an artificial language. Hebrew is interesting because its complex Semitic morphological structure has been found to play a central role in lexical access, allowing us to examine whether morphological properties can modulate the C-bias in early phases of speech perception, namely, word segmentation. As predicted, we found a significant interaction between language and consonant/vowel manipulation, with a higher performance in the consonantal condition than in the vowel condition for Hebrew speakers, namely, C-bias, and no consonant/vowel asymmetry among English speakers. We suggest that the observed interaction is morphologically anchored, indicating that phonological and morphological processes interact during early phases of auditory word perception.

Learnability Advantage of Segmental Repetitions in Word Learning

To date, research on wordform learning biases has mostly focused on language-dependent factors, such as the phonotactics and neighborhood density of the language(s) known by the learner. Domain-general biases, by contrast, have received little attention. In this study, we focus on one such bias-an advantage for string-internal repetitions-and examine its effects on wordform learning. Importantly, we consider whether any type of segmental repetition is equally beneficial for word recall, or whether learning is favored more or only by repeated consonants, in line with previous research indicating that consonants play a larger role than vowels in lexical processing. In Experiment 1, adult English speakers learned artificial consonant-vowel-consonant-vowel words containing either a repeated consonant (e.g., /sesu/, "c-rep"), a repeated vowel (e.g., /sepe/, "v-rep"), or dissimilar consonants and vowels (e.g., /sepu/, "no-rep"). Recall results showed no advantage for v-reps but higher accuracy for c-reps compared with no-reps. In Experiment 2, participants performed a label preference task with the same stimuli. The results showed dispreference for both c-reps and v-reps relative to no-reps, indicating that the results of Experiment 1 are independent of wordlikeness effects. These outcomes reveal that there is a form-learning bias for words with identical consonants but not for words with identical vowels, suggesting that a domain-general advantage for repetitions within strings is modulated by a language-specific processing bias for consonants.

Danish 20-month-olds' recognition of familiar words with and without consonant and vowel mispronunciations

Although several studies initially supported the proposal by Nespor et al. (Nespor, Marina, Marcela Peña & Jacques Mehler. 2003. On the different roles of vowels and consonants in speech processing and language acquisition. Lingue e Linguaggio 2. 221-247) that consonants are more informative than vowels in lexical processing, a more complex picture has emerged from recent research. Current evidence suggests that infants initially show a vowel bias in lexical processing and later transition to a consonant bias, possibly depending on the characteristics of the ambient language. Danish infants have shown a vowel bias in word learning at 20 months-an age at which infants learning French or Italian no longer show a vowel bias but rather a consonant bias, and infants learning English show no bias. The present study tested whether Danish 20-month-olds also have a vowel bias when recognizing familiar words. Specifically, using the Intermodal Preferential Looking paradigm, we tested whether Danish infants were more likely to ignore or accept consonant than vowel mispronunciations when matching familiar words with pictures. The infants successfully matched correctly pronounced familiar words with pictures but showed no vowel or consonant bias when matching mispronounced words with pictures. The lack of a bias for Danish vowels or consonants in familiar word recognition adds to evidence that lexical processing biases are language-specific and may additionally depend on developmental age and perhaps task difficulty.

Maturation of consonant perception, but not vowel perception, predicts lexical skills at 12 months

Consonants and vowels differentially contribute to lexical acquisition. From 8 months on, infants' preferential reliance on consonants has been shown to predict their lexical outcome. Here, the predictive value of German-learning infants' (n = 58, 29 girls, 29 boys) trajectories of consonant and vowel perception, indicated by the electrophysiological mismatch response, across 2, 6, and 10 months for later lexical acquisition was studied. The consonant-perception trajectory from 2 to 6 months (β = -2.95) and 6 to 10 months (β = -.91), but not the vowel-perception trajectory, significantly predicted receptive vocabulary at 12 months. These results reveal an earlier predictive value of consonant perception for word learning than previously found, and a particular role of the longitudinal maturation of this skill in lexical acquisition.