Recent research has shown that 6-month-olds relate novel words suffixed with -s, like babs, that are embedded in passages, with just the stem bab, demonstrating an early sensitivity to morphological relatedness. This study builds on these findings by investigating the role of allomorphy in early morphological acquisition. We tested whether infants relate novel words suffixed with [-z] and [-s] allomorphs of the -s suffix and their stems. We find that English-learning 6-month-olds relate novel words suffixed with the [-z], but not [-s], allomorph with stems, providing evidence for an acquisition trajectory where infants discover morphemes one allomorph at a time.

We characterised language samples collected remotely from typically developing three-year-olds by comparing them against independent language samples collected in person from age-matched peers with and without language delays. Forty-eight typically developing, English-learning three-year-olds were administered a picture description task via Zoom. The in-person comparison groups were two sets of independent language samples from age-matched typically developing as well as language-delayed children available on the Child Language Data Exchange System. The findings show that although language samples collected remotely from three-year-olds yield numerically dissimilar lexical and grammatical measures compared to samples collected in person, they still consistently distinguish toddlers with and without language delays.

We evaluated the impact of exposure to a second language on infants’ emerging speech production skills. We compared speech produced by three groups of 12-month-old infants while they interacted with interlocutors who spoke to them in Spanish and English: monolingual English-learning infants who had previously received 5 hours of exposure to a second language (Spanish), English- and Spanish-learning simultaneous bilinguals, and monolingual English-learning infants without any exposure to Spanish. Our results showed that the monolingual English-learning infants with short-term exposure to Spanish and the bilingual infants, but not the monolingual English-learning infants without exposure to Spanish, flexibly matched the prosody of their babbling to that of a Spanish- or English-speaking interlocutor. Our findings demonstrate the nature and extent of benefits for language learning from early exposure to two languages. We discuss the implications of these findings for language organization in infants learning two languages.

Children pay more attention to the beginnings and ends of sentences rather than the middle. In natural speech, ends of sentences are prosodically and segmentally enhanced; they are also privileged by sensory and recall advantages. We contrasted whether acoustic enhancement or sensory and recall-related advantages are necessary and sufficient for the salience of grammatical morphemes at the ends of sentences. We measured 22-month-olds’ listening times to grammatical and ungrammatical sentences with third person singular -s. Crucially, by cross-splicing the speech stimuli, acoustic enhancement and sensory and recall advantages were fully crossed. Only children presented with the verb in sentence-final position, a position with sensory and recall advantages, distinguished between the grammatical and ungrammatical sentences. Thus, sensory and recall advantages alone were necessary and sufficient to make grammatical morphemes at ends of sentences salient. These general processing constraints privilege ends of sentences over middles, regardless of the acoustic enhancement.

The majority of research examining infants’ decontextualized word knowledge comes from studies in which words and pictures are presented simultaneously. However, comprehending utterances about unseen objects is a hallmark of language. Do infants demonstrate decontextualized absent object knowledge early in the second year of life? Further, to what extent do words evoke strictly prototypical representations of absent objects? To investigate these questions we analyzed 14-month-olds’ comprehension of labels for absent entities without contextual support. In a novel, auditory–visual priming paradigm, infants heard passages containing two target words and then saw four animations – two that matched the meaning of the target words and two they had not heard in the passages. We found that by age 1;2, spoken words evoke prototypical representations of absent entities. Additionally, our findings demonstrate a promising new method for exploring absent object comprehension in infants.

Within the first year of life, infants learn to segment words from fluent speech. Previous research has shown that infants at 0;7·5 can segment consonant-initial words, yet the ability to segment vowel-initial words does not emerge until the age of 1;1–1;4 (0;11 in some restricted cases). In five experiments, we show that infants aged 0;11 but not 0;8 are able to segment vowel-initial words that immediately follow the function word the [ði], while ruling out a bottom-up, phonotactic account of these results. Thus, function words facilitate the segmentation of vowel-initial words that appear sentence-medially for infants aged 0;11.

Six experiments explored Parisian French-learning infants' ability to segment bisyllabic words from fluent speech. The first goal was to assess whether bisyllabic word segmentation emerges later in infants acquiring European French compared to other languages. The second goal was to determine whether infants learning different dialects of the same language have partly different segmentation abilities, and whether segmenting a non-native dialect has a cost. Infants were tested on standard European or Canadian French stimuli, in the word–passage or passage–word order. Our study first establishes an early onset of segmentation abilities: Parisian infants segment bisyllabic words at age 0;8 in the passage–word order only (revealing a robust order of presentation effect). Second, it shows that there are differences in segmentation abilities across Parisian and Canadian French infants, and that there is a cost for cross-dialect segmentation for Parisian infants. We discuss the implications of these findings for understanding word segmentation processes.

This study investigated acoustic-phonetics of coronal stop production by adult simultaneous bilingual and monolingual speakers of Canadian English (CE) and Canadian French (CF). Differences in the phonetics of CF and CE include voicing and place of articulation distinctions. CE has a two-way voicing distinction (in syllable initial position) contrasting short-and long-lag VOT; coronal stops in CE are described as alveolar. CF also has a two-way voicing distinction, but contrasting lead and short-lag VOT; coronal stops in CF are described as dental. Acoustic analyses of stop consonants for both VOT and dental/alveolar place of articulation are reported. Results indicate that simultaneous bilingual as well as monolingual adults produce language-specific differences, albeit not in the same way, across CF and CE for voicing and place. Similarities and differences between simultaneous bilingual and monolingual adults are discussed to address phonological organization in simultaneous bilingual adults.