There might be more to syntactic bootstrapping than being pragmatic: A look at grammatical person and prosody in naturalistic child-directed speech.

In 'Being pragmatic about syntactic bootstrapping', Hacquard (2022) argues that abstract syntax is useful for word learning, but that an additional cue, pragmatics, is both necessary and available for young children during the first steps of language acquisition. She focuses on modals and attitude verbs, where the physical context seems particularly impoverished as the sole basis for deriving meanings, and thus where linguistic cues may be particularly helpful. She convincingly shows how pragmatic and syntactic cues could be combined to help young language learners learn and infer the possible meanings of attitude verbs such as "think", "know" or "want". She also argues that, in some circumstances, syntax and pragmatics would need to be supplemented by semantic information from context - for instance, in the case of modals such as "might", "can", or "must". We agree with Hacquard on the importance of the synergies between these different cues to meaning, and wish to add two other aspects of the input that might also be used by young children in these contexts. The aspects we describe can only be noticed when one analyzes concrete examples of what children hear in their everyday lives, something which Hacquard does very often in her work (e.g., Dieuleveut, van Dooren, Cournane & Hacquard, 2022; Huang, White, Liao, Hacquard & Lidz, 2022; Yang, 2022). Taking into account different cues for meaning would help the field go beyond current models of syntactic bootstrapping, and create an integrated picture of the synergies between different levels of linguistic information.

Rapid infant learning of syntactic-semantic links.

In the second year of life, infants begin to rapidly acquire the lexicon of their native language. A key learning mechanism underlying this acceleration is syntactic bootstrapping: the use of hidden cues in grammar to facilitate vocabulary learning. How infants forge the syntactic-semantic links that underlie this mechanism, however, remains speculative. A hurdle for theories is identifying computationally light strategies that have high precision within the complexity of the linguistic signal. Here, we presented 20-mo-old infants with novel grammatical elements in a complex natural language environment and measured their resultant vocabulary expansion. We found that infants can learn and exploit a natural language syntactic-semantic link in less than 30 min. The rapid speed of acquisition of a new syntactic bootstrap indicates that even emergent syntactic-semantic links can accelerate language learning. The results suggest that infants employ a cognitive network of efficient learning strategies to self-supervise language development.

When language-general and language-specific processes are in conflict: The case of sub-syllabic word segmentation in toddlers.

Infants use statistics-based word segmentation strategies from the preverbal stage. Statistical segmentation is, however, constrained by the Onset Bias, a language-universal principle that disfavors segmentation that harms syllable integrity. Children eventually learn language-specific exceptions to this principle. For instance, sub-syllabic parsing occurs for vowel-initial words in French liaison contexts, that is, when a word's final consonant surfaces as the following word's syllabic onset (e.g., /n/ in un /n/éléphant). In past research, French-learning 24-month-olds succeeded in parsing a vowel-initial pseudo-word surfacing with variable liaison consonants. This study further investigated infants' liaison representation, its potential impacts on parsing, and its interaction with the Onset Bias. In Experiments 1 and 2, French-learning 24-month-olds were familiarized with pseudo-words with variable liaison-like versus nonliaison-like onset consonants, preceded by words that cannot trigger those onsets (e.g., un zonche; un gonche). We found no mis-segmentation as vowel-initial and successful segmentation as consonant-initial. In Experiment 3, when the preceding words could trigger a liaison consonant that matched the onset of the following word (e.g., un nonche), infants showed a vowel-initial mis-interpretation, against the Onset Bias, revealing an effect of liaison knowledge. These results demonstrate that toddlers balance their use of language-general principles/strategies and language-specific knowledge during early acquisition.

Preverbal infants' sensitivity to grammatical dependencies.

During their first months of life, infants can already distinguish function words (e.g., pronouns and determiners) from content words (e.g., verbs and nouns). Little research has explored preverbal infants' sensitivity to the relationships between these word categories. This preregistered study examines whether French-learning 8- and 11-month-olds track the grammatical dependencies between determiners and nouns as well as pronouns and verbs. Using the Visual Fixation Procedure, infants were presented with lists containing either grammatical (e.g., tu manges "you eat", des biberons "some bottles") or ungrammatical (e.g., des manges "some eat", tu biberons "you bottle") phrases. In Experiment 1 (N = 59), the lists involved common nouns and verbs, while in Experiment 2 (N = 28), only common verbs were used. Eleven-month-olds showed a clear preference for correct over incorrect co-occurrences in both experiments, while 8-month-olds showed a trend in the same direction. These results suggest that before their first birthday, infants' storage and access of words and word sequences are sufficiently sophisticated to include the means to track categorical dependencies. This early sensitivity to co-occurrence patterns may be greatly beneficial for constraining lexical access and later on for learning novel words' syntactic and semantic properties.

Variable forms in French-learning toddlers' lexical representations.

We investigated toddlers' phonological representations of common vowel-initial words that can take on multiple surface forms in the input. In French, liaison consonants are inserted and are syllabified as onsets in subsequent vowel-initial words, for example, petit /t/ éléphant [little elephant]. We aimed to better understand the impact on children's early lexical representations of this frequent intrusion by consonants by testing whether toddlers store multiple forms for vowel-initial words (e.g., téléphant, zéléphant) early in acquisition. Thirty-one Quebec French-learning 30-month-olds completed an eye-tracking experiment (16 girls). Children were predominantly from White, middle-class families living in a large urban area (Montreal). Each trial presented two objects while one of them was named. There were four key trial types: (a) correct vowel-initial (e.g., joli éléphant [pretty elephant]); (b) pragmatically incorrect frequent intrusion (e.g., joli zéléphant, /z/ intrusion [pretty elephants], which is grammatically acceptable but does not correspond to the picture); (c) lexically incorrect frequent intrusion (e.g., joli téléphant, /t/ intrusion, as /t/ is a frequent liaison consonant in general but is impossible with joli); (d) lexically incorrect infrequent intrusion (e.g., joli géléphant, /g/ intrusion, as /g/ is an infrequent liaison consonant and is also impossible with joli). The results showed that target recognition was successful in the frequent /t/- and /z/-intrusion trials and was also evident in the vowel-initial trials, whereas it was impeded in the infrequent /g/-intrusion trials. Our findings demonstrate that French-learning children's early lexicon contains multiple variants for words that are subject to phonological alternations, including frequent liaison-consonant variants. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

"The tiger is hitting! the duck too!" 3-year-olds can use prosodic information to constrain their interpretation of ellipsis.

This work aims to investigate French children's ability to use phrasal boundaries for disambiguation of a type of ambiguity not yet studied, namely stripping sentences versus simple transitive sentences. We used stripping sentences such as "[Le tigre tape]! [Le canard aussi]!" ("[The tiger is hitting]! [The duck too]!", in which both the tiger and the duck are hitting), which, without the prosodic information, would be ambiguous with a transitive sentence such as "[Le tigre] [tape le canard aussi]!" ("[The tiger] [is hitting the duck too]!", in which the tiger is hitting the duck). We presented 3-to-4-year-olds and 28-month-olds with one of the two types of sentence above, while they watched two videos side-by-side on a screen: one depicting the transitive interpretation of the sentences, and another depicting the stripping interpretation. The stripping interpretation video showed the two characters as agents of the named action (e.g. a duck and a tiger hitting a bunny), and the transitive interpretation video showed only the first character as an agent, and the second character as a patient of the action (e.g. the tiger hitting the duck and the bunny). The results showed that 3-to-4-year-olds use prosodic information to correctly distinguish stripping sentences from transitive sentences, as they looked significantly more at the appropriate video, while 28-month-olds show only a trend in the same direction. While recent studies demonstrated that from 18 months of age, infants are able to use phrasal prosody to guide the syntactic analysis of ambiguous sentences, our results show that only 3-to-4-year-olds were able to reliably use phrasal prosody to constrain the parsing of stripping sentences. We discuss several factors that can explain this delay, such as differences in the frequency of these structures in child-directed speech, as well as in the complexity of the sentences and of the experimental task. Our findings add to the growing body of evidence on the role of prosody in constraining parsing in young children.

18-month-olds fail to use recent experience to infer the syntactic category of novel words.

Infants are able to use the contexts in which familiar words appear to guide their inferences about the syntactic category of novel words (e.g. 'This is a' + 'dax' -> dax = object). The current study examined whether 18-month-old infants can rapidly adapt these expectations by tracking the distribution of syntactic structures in their input. In French, la petite can be followed by both nouns (la petite balle, 'the little ball') and verbs (la petite mange, 'the little one is eating'). Infants were habituated to a novel word, as well as to familiar nouns or verbs (depending on the experimental group), all appearing after la petite. The familiar words served to create an expectation that la petite would be followed by either nouns or verbs. If infants can utilize their knowledge of a few frequent words to adjust their expectations, then they could use this information to infer the syntactic category of a novel word - and be surprised when the novel word is used in a context that is incongruent with their expectations. However, infants in both groups did not show a difference between noun and verb test trials. Thus, no evidence for adaptation-based learning was found. We propose that infants have to entertain strong expectations about syntactic contexts before they can adapt these expectations based on recent input.

Familiar words can serve as a semantic seed for syntactic bootstrapping.

Young children can exploit the syntactic context of a novel word to narrow down its probable meaning. But how do they learn which contexts are linked to which semantic features in the first place? We investigate if 3- to 4-year-old children (n = 60) can learn about a syntactic context from tracking its use with only a few familiar words. After watching a 5-min training video in which a novel function word (i.e., 'ko') replaced either personal pronouns or articles, children were able to infer semantic properties for novel words co-occurring with the newly learned function word (i.e., objects vs. actions). These findings implicate a mechanism by which a distributional analysis, associated with a small vocabulary of known words, could be sufficient to identify some properties associated with specific syntactic contexts.

14-month-olds exploit verbs' syntactic contexts to build expectations about novel words.

During their second year of life, infants develop a rudimentary understanding of grammatical categories based on their knowledge and use of frequent function words. The current study inquired whether, at only 14 months of age, infants can track co-occurrence patterns between function words and content words (e.g., determiners can precede nouns, and pronouns can precede verbs), and use these previously encountered syntactic contexts to build expectations about which function words can co-occur with novel words. Using a habituation paradigm, French-learning 14-month-olds were presented with utterances containing two novel words preceded by function words (either two determiners in the Novel Nouns condition or two pronouns in the Novel Verbs conditions). We found that at test, infants looked longer during trials in which the novel words occurred in an unexpected syntactic context (following a pronoun for infants in the Novel Nouns condition and following a determiner for infants in the pooled analysis of the three Novel Verbs conditions). Hence, our results confirm previous findings on infants' sensitivity to noun contexts and most importantly demonstrate that their sensitivity to the co-occurrence of verbs with pronouns begins much earlier than previously understood.

Studying the Real-Time Interpretation of Novel Noun and Verb Meanings in Young Children.

Decades of research show that children rely on the linguistic context in which novel words occur to infer their meanings. However, because learning in these studies was assessed after children had heard numerous occurrences of a novel word in informative linguistic contexts, it is impossible to determine how much exposure would be needed for a child to learn from such information. This study investigated the speed with which French 20-month-olds and 3-to-4-year-olds exploit function words to determine the syntactic category of novel words and therefore infer their meanings. In a real-time preferential looking task, participants saw two videos side-by-side on a TV-screen: one showing a person performing a novel action, and the other a person passively holding a novel object. At the same time, participants heard only three occurrences of a novel word preceded either by a determiner (e.g., "Regarde! Une dase! - "Look! A dase!") or a pronoun (e.g., "Regarde! Elle dase!" - "Look! She's dasing!"). 3-to-4-year-olds exploited function words to categorize novel words and infer their meanings: they looked more to the novel action in the verb condition, while participants in the noun condition looked more to the novel object. 20-month-olds, however, did not show this difference. We discuss possible reasons for why 20-month-olds may have found it difficult to infer novel word meanings in our task. Given that 20-month-olds can use function words to learn word meanings in experiments providing many repetitions, we suspect that more repetitions might be needed to observe positive effects of learning in this age range in our task. Our study establishes nevertheless that before age 4, young children become able to exploit function words to infer the meanings of unknown words as soon as they occur. This ability to interpret speech in real-time and build interpretations about novel word meanings might be extremely useful for young children to map words to their possible referents and to boost their acquisition of word meanings.

The Missing-Phoneme Effect in Aural Prose Comprehension.

When participants search for a target letter while reading for comprehension, they miss more instances if the target letter is embedded in frequent function words than in less frequent content words. This phenomenon, called the missing-letter effect, has been considered a window on the cognitive mechanisms involved in the visual processing of written language. In the present study, one group of participants read two texts for comprehension while searching for a target letter, and another group listened to a narration of the same two texts while listening for the target letter's corresponding phoneme. The ubiquitous missing-letter effect was replicated and extended to a missing-phoneme effect Item-based correlations between the reading and listening tasks were high, which led us to conclude that both tasks involve cognitive processes that reading and listening have in common and that both processes are rooted in psycholinguistically driven allocation of attention.

Distributional cues and the onset bias in early word segmentation.

In previous infant studies on statistics-based word segmentation, the unit of statistical computation was always aligned with the syllabic edge, which had a consonant onset. The current study addressed whether the learning system imposes a constraint that favors word forms beginning with a consonant onset over those beginning with an onsetless sub-syllable, by examining infants' segmentation of vowel-initial non-words in French liaison. French-learning 20- and 24-month-old infants (N = 64) were familiarized with sentences containing variable liaison consonants preceding the same vowel-initial non-word (e.g., /n/onche, /z/onche, /r/onche, /t/onche), such that the distributional cues supported the sub-syllabic target (e.g., onche). After familiarization, we tested sub-syllabic statistical segmentation by presenting the vowel-initial target (e.g., onche) versus another non-familiarized vowel-initial word (e.g., èque). Another group of infants was tested with a consonant-initial mis-segmentation of the target (e.g., zonche) versus another non-familiarized consonant-initial word (e.g., zèque). Results showed that 20-month-olds failed to segment the vowel-initial targets, but they mis-segmented the targets as consonant-initial, indicating that the onset bias dominated over sub-syllabic statistics for word segmentation at this age. Twenty-four-month-olds showed ambiguous interpretations (i.e., both vowel-initial segmentation and consonant-initial mis-segmentation), suggesting that the use of statistics to segment sub-syllabic words was emerging while the onset bias continued to have an impact.