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.

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

Consonants and vowels have been considered to fulfill different functions in language processing, vowels being more important for prosodic and syntactic processes and consonants for lexically related processes (Nespor, Peña, & Mehler, 2003). This C-bias hypothesis in lexical processing is supported by studies with adults and infants in many languages such as English, French, Spanish, although a few studies, on Danish and Mandarin, suggest the existence of cross-linguistic variation. The present study explores whether a C-bias exists in a tone language with a complex tone system, Cantonese, by comparing the relative weight given to consonants, vowels, and also tones during word learning. To do so, looking behaviors of Cantonese-learning 20- and 30-month-olds (24 children per age/condition, 6 groups) were recorded by an eyetracker while they watched animated cartoons in Cantonese to learn pairs of novel words. The words differed minimally by either a consonant (e.g., /tœ6/ vs. /kœ6/), a vowel (e.g., /khim3/ vs. /khɛm3/), or a tone (e.g., T2 vs. T5). Analyses on proportional looking times revealed significant learning in 30-month-olds only, and at that age, only for the vowel contrasts. Growth curve analyses revealed better performance for the vowel condition compared to the other two conditions. The present findings establish a V-bias in Cantonese-learning 30-month-olds, adding new evidence from that tone language that the C-bias in lexical processing is not language-general. Implications for theoretical discussions on the origins of this phonological bias, and the impact of tones in early language acquisition, are discussed.