Sounds and meanings working together: Word learning as a collaborative effort

Combining statistics: the role of phonotactics on cross-situational word learning

Language learners can rely on phonological and semantic information to learn novel words. Using a cross-situational word learning paradigm, we explored the role of phonotactic probabilities on word learning in ambiguous contexts. Brazilian-Portuguese speaking adults (N = 30) were exposed to two sets of word-object pairs. Words from one set of labels had slightly higher phonotactic probabilities than words from the other set. By tracking co-occurrences of words and objects, participants were able to learn word-object mappings similarly across both sets. Our findings contrast with studies showing a facilitative effect of phonotactic probability on word learning in non-ambiguous contexts.

Phonemic contrasts under construction? Evidence from Basque

Attunement theories of speech perception development suggest that native-language exposure is one of the main factors shaping infants' phonemic discrimination capacity within the second half of their first year. Here, we focus on the role of acoustic-perceptual salience and language-specific experience by assessing the discrimination of acoustically subtle Basque sibilant contrasts. We used the infant-controlled version of the habituation procedure to assess discrimination in 6- to 7-month and 11- to 12-month-old infants who varied in their amount of exposure to Basque and Spanish. We observed no significant variation in the infants' discrimination behavior as a function of their linguistic experience. Infants in both age-groups exhibited poor discrimination, consistent with Basque adults finding these contrasts more difficult than some others. Our findings are in agreement with previous research showing that perceptual discrimination of subtle speech sound contrasts may follow a different developmental trajectory, where increased native-language exposure seems to be a requisite.

Monolingual and Bilingual Infants' Ability to Use Non-native Tone for Word Learning Deteriorates by the Second Year After Birth

Previous studies reported a non-native word learning advantage for bilingual infants at around 18 months. We investigated developmental changes in infant interpretation of sounds that aid in object mapping. Dutch monolingual and bilingual (exposed to Dutch and a second non-tone-language) infants' word learning ability was examined on two novel label-object pairings using syllables differing in Mandarin tones as labels (flat vs. falling). Infants aged 14-15 months, regardless of language backgrounds, were sensitive to violations in the label-objects pairings when lexical tones were switched compared to when they were the same as habituated. Conversely at 17-18 months, neither monolingual nor bilingual infants demonstrated learning. Linking with existing literature, infants' ability to associate non-native tones with meanings may be related to tonal acoustic properties and/or perceptual assimilation to native prosodic categories. These findings provide new insights into the relation between infant tone perception, learning, and interpretative narrowing from a developmental perspective.

Neurophysiological evidence for the interplay of speech segmentation and word-referent mapping during novel word learning

Learning a new language requires the identification of word units from continuous speech (the speech segmentation problem) and mapping them onto conceptual representation (the word to world mapping problem). Recent behavioral studies have revealed that the statistical properties found within and across modalities can serve as cues for both processes. However, segmentation and mapping have been largely studied separately, and thus it remains unclear whether both processes can be accomplished at the same time and if they share common neurophysiological features. To address this question, we recorded EEG of 20 adult participants during both an audio alone speech segmentation task and an audiovisual word-to-picture association task. The participants were tested for both the implicit detection of online mismatches (structural auditory and visual semantic violations) as well as for the explicit recognition of words and word-to-picture associations. The ERP results from the learning phase revealed a delayed learning-related fronto-central negativity (FN400) in the audiovisual condition compared to the audio alone condition. Interestingly, while online structural auditory violations elicited clear MMN/N200 components in the audio alone condition, visual-semantic violations induced meaning-related N400 modulations in the audiovisual condition. The present results support the idea that speech segmentation and meaning mapping can take place in parallel and act in synergy to enhance novel word learning.