Toddlers default to canonical surface-to-meaning mapping when learning verbs

Do focused interests support word learning? A study with autistic and nonautistic children

Although focused interests are often associated with a diagnosis of autism, they are common in nonautistic individuals as well. Previous studies have explored how these interests impact cognitive, social, and language development. While some research has suggested that strong interests can detract from learning (particularly for autistic children), newer research has indicated that they can be advantageous. In this pre-registered study, we asked whether focused interests support word learning in 44 autistic children and a vocabulary-matched sample of 44 nonautistic children (mean ages 58 and 34 months respectively). In a word-learning task administered over Zoom, children were exposed to an action labeled by a novel word. The action was either depicted by their focused interest or by a neutral image; stimuli were personalized for each child. At test, they were asked to identify the referent of the novel word, and their eye gaze was evaluated as a measure of learning. The preregistered analyses revealed an effect of focused interests, and post-hoc analyses clarified that autistic children learned the novel word in both the focused interest and neutral conditions, while nonautistic children only showed evidence of learning in the neutral condition. These results suggest that focused interests are not disruptive for vocabulary learning in autism, and thus they could be utilized in programming that supports early language learning in this population.

Who "it" is influences what "it" does: Discourse effects on children's syntactic parsing

Children often interpret first noun phrases (NP1s) as agents, which improves comprehension of actives but hinders passives. While children sometimes withhold the agent-first bias, the reasons remain unclear. The current study tests the hypothesis that children default to the agent-first bias as a "best guess" of role assignment when they face uncertainty about sentence properties. Thus, rather than always relying on early-arriving cues, children can attend to different sentence cues across communicative contexts. To test this account, we manipulated interpretive uncertainty by varying cues to the discourse status of initial arguments (referring to new vs. given entities) and measured interpretation accuracy for active (where the agent-first bias predicted verb morphology) and passive sentences (where the two conflicted). Across three experiments, we found that children relied on the agent-first bias more when new discourse entities were signaled by definite NP1s, reference to unmentioned entities, and novel words. This, in turn, led to higher accuracy for actives relative to passives. In contrast, when given entities were implied through pronoun NP1s, reference to mentioned entities, and known words, children avoided the agent-first bias and instead assigned roles using more reliable but later-arriving verb morphology. This led to similar comprehension accuracy across constructions. These findings suggest that children simultaneously interpret relations between sentences (e.g., discourse continuity) and within sentences (e.g., role assignment), such that commitments to the former can influence parsing cues for the latter.

The Acquisition of Noun and Verb Categories by Bootstrapping From a Few Known Words: A Computational Model

While many studies have shown that toddlers are able to detect syntactic regularities in speech, the learning mechanism allowing them to do this is still largely unclear. In this article, we use computational modeling to assess the plausibility of a context-based learning mechanism for the acquisition of nouns and verbs. We hypothesize that infants can assign basic semantic features, such as “is-an-object” and/or “is-an-action,” to the very first words they learn, then use these words, the semantic seed, to ground proto-categories of nouns and verbs. The contexts in which these words occur, would then be exploited to bootstrap the noun and verb categories: unknown words are attributed to the class that has been observed most frequently in the corresponding context. To test our hypothesis, we designed a series of computational experiments which used French corpora of child-directed speech and different sizes of semantic seed. We partitioned these corpora in training and test sets: the model extracted the two-word contexts of the seed from the training sets, then used them to predict the syntactic category of content words from the test sets. This very simple algorithm demonstrated to be highly efficient in a categorization task: even the smallest semantic seed (only 8 nouns and 1 verb known) yields a very high precision (~90% of new nouns; ~80% of new verbs). Recall, in contrast, was low for small seeds, and increased with the seed size. Interestingly, we observed that the contexts used most often by the model featured function words, which is in line with what we know about infants' language development. Crucially, for the learning method we evaluated here, all initialization hypotheses are plausible and fit the developmental literature (semantic seed and ability to analyse contexts). While this experiment cannot prove that this learning mechanism is indeed used by infants, it demonstrates the feasibility of a realistic learning hypothesis, by using an algorithm that relies on very little computational and memory resources. Altogether, this supports the idea that a probabilistic, context-based mechanism can be very efficient for the acquisition of syntactic categories in infants.

"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.

"Look! It is not a bamoule!": 18- and 24-month-olds can use negative sentences to constrain their interpretation of novel word meanings

Two word-learning experiments were conducted to investigate the understanding of negative sentences in 18- and 24-month-old children. In Experiment 1, after learning that bamoule means "penguin" and pirdaling means "cartwheeling," 18-month-olds (n = 48) increased their looking times when listening to negative sentences rendered false by their visual context ("Look! It is not a bamoule!" while watching a video showing a penguin cartwheeling); however, they did not change their looking behavior when negative sentences were rendered true by their context ("Look! It is not pirdaling!" while watching a penguin spinning). In Experiment 2, 24-month-olds (n = 48) were first exposed to a teaching phase in which they saw a new cartoon character on a television (e.g., a blue monster). Participants in the affirmative condition listened to sentences like "It's a bamoule!" and participants in the negative condition listened to sentences like "It's not a bamoule!." At test, all participants were asked to find the bamoule while viewing two images: the familiar character from the teaching phase versus a novel character (e.g., a red monster). Results showed that participants in the affirmative condition looked more to the familiar character (i.e., they learned the familiar character was a bamoule) than participants in the negative condition. Together, these studies provide the first evidence for the understanding of negative sentences during the second year of life. The ability to understand negative sentences so early might support language acquisition, providing infants with a tool to constrain the space of possibilities for word meanings.

Toddlers exploit referential and syntactic cues to flexibly adapt their interpretation of novel verb meanings

Because linguistic communication is often noisy and uncertain, adults flexibly rely on different information sources during sentence processing. We tested whether toddlers engage in a similar process and how that process interacts with verb learning. Across two experiments, we presented French 28-month-olds with right-dislocated sentences featuring a novel verb ("He_i is VERBing, the boy_i"), where a clear prosodic boundary after the verb indicates that the sentence is intransitive (such that the NP "the boy" is coreferential with the pronoun "he" and the sentence means "The boy is VERBing"). By default, toddlers incorrectly interpreted the sentence based on the number of NPs (assuming, e.g., that someone is VERBing the boy). Yet, when children were provided with additional information about the syntactic contexts (Experiment 1, N = 81) or the referential/semantic content (Experiment 2, N = 72) of the novel verb, they successfully used the prosodic information as a cue to reach the correct syntactic structure of the sentence and infer the probable meaning of the novel verb. These results suggest that toddlers can flexibly adjust their interpretations of sentences depending on the reliability of the linguistic cues available. Thus, failure to parse a sentence in an adult-like fashion might not necessarily reflect the immaturity of children's parsing system but rather might be indicative of what cues children consider reliable in that context.

Syntactic Cues Help Disambiguate Objects Referred to With Count Nouns: Illustration With Malay Children

Children employ multiple cues to identify the referent of a novel word. Novel words are often embedded in sentences and children have been shown to use syntactic cues to differentiate between types of words (adjective vs. nouns) and between types of nouns (count vs. mass nouns). In this study, we show that children learning Malay (N = 67), a numeral classifier language, can use syntactic cues to perform even finer-grained disambiguation-between count nouns. The manipulation of congruence between lexical and syntactic cues reveals a clear developmental trajectory: while 5-year-olds use predominantly lexical cues, older children increasingly rely on syntactic cues, such that by 7 years of age, they disambiguate between objects referred to with count nouns using syntactic rather than lexical cues.

Two-year-olds consolidate verb meanings during a nap

Successful word learning requires establishing an initial representation that is sufficiently robust to be retained in memory. Sleep has profound advantages for memory consolidation, but evidence concerning the effects of sleep in young children's word learning is slim and focuses almost exclusively on learning nouns. Verbs are representationally more complex and are often learned from non-concurrent linguistic and observational information (e.g., hearing "let's pour your milk" before the pouring event takes place). What remains unknown is whether initial representations built this way are robust enough to sustain a delay, and how these representations are affected by sleep. We presented two-year-olds with non-concurrent linguistic and observational information about novel verbs and immediately tested their knowledge of the verbs' meanings by evaluating their eye gaze as they looked at potential referents. Then, after a 4-hour delay during which half of the children napped and half remained awake, we retested them to see if they remembered the verbs' meanings. The results demonstrate differences in two-year-olds' representations of a novel verb before and after the delay; specifically, their verb representations withstood the 4-hour delay if they had napped, but decayed if they had remained awake.

The Developmental Origins of Syntactic Bootstrapping

Children use syntax to learn verbs, in a process known as syntactic bootstrapping. The structure-mapping account proposes that syntactic bootstrapping begins with a universal bias to map each noun phrase in a sentence onto a participant role in a structured conceptual representation of an event. Equipped with this bias, children interpret the number of noun phrases accompanying a new verb as evidence about the semantic predicate-argument structure of the sentence, and therefore about the meaning of the verb. In this paper, we first review evidence for the structure-mapping account, and then discuss challenges to the account arising from the existence of languages that allow verbs' arguments to be omitted, such as Korean. These challenges prompt us to (a) refine our notion of the distributional learning mechanisms that create representations of sentence structure, and (b) propose that an expectation of discourse continuity allows children to gather linguistic evidence for each verb's arguments across sentences in a coherent discourse. Taken together, the proposed learning mechanisms and biases sketch a route whereby simple aspects of sentence structure guide verb learning from the start of multi-word sentence comprehension, and do so even if some of the new verb's arguments are omitted due to discourse redundancy.

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.

Semantic detail in the developing verb lexicon: An extension of Naigles and Kako (1993)

Verbs are often uttered before the events they describe. By 2 years of age, toddlers can learn from such an encounter. Hearing a novel verb in transitive sentences (e.g. The boy lorped the cat), even with no visual referent present, they later map it to a causative meaning (e.g. feed) (e.g. Yuan & Fisher, ). How much semantic detail does their verb representation include on this first, underinformative, encounter? Is the representation sparse, including only information for which they have evidence, or do toddlers make more specific guesses about the verb's meaning? In two experiments (N = 76, mean age 27 months), we address this using an event type studied by Naigles and Kako (); they found that when toddlers hear a novel transitive verb while simultaneously viewing a non-causative referent-a contact event such as patting-they map the verb to the contact event. In Experiment 1 we replicated this basic result. Further, toddlers' representations persisted over a 5-minute delay, manifesting again during a retest. In Experiment 2, toddlers heard the verbs while watching two actors converse instead of while seeing contact events. At test, they showed no evidence of mapping the verbs to contact events, either initially or after a 5-minute delay, despite that in prior work they mapped verbs to causative events under identical circumstances. We infer that on hearing a novel verb in a transitive frame, absent a relevant visual scene, toddlers posit a more specific representation than the evidence requires-one that incorporates causative semantics. A video abstract of this article can be viewed at: https://youtu.be/aRCqSTbr6Bw.

Children's syntactic representation of the transitive constructions in Mandarin Chinese

Two studies are presented that investigate the effect of linguistic cues on Mandarin speakers' comprehension of transitive constructions. Study 1 investigated Mandarin-speaking 2- to 4-year-olds' and adults' comprehension of the SVO (Subject-verb-object) construction, ba-construction (SbaOV), and subjectless ba-construction ((S)baOV) with novel verbs using the forced choice pointing paradigm (FCPP). Study 2 investigated another group of participants with similar ages' comprehension of the SVO construction, the ba-construction, the long and short passive constructions with novel verbs and FCPP. Although these constructions have differing cue strengths, participants in the same age groups comprehended these construction types equally well. The results suggest that children as young as two attended to the case markers of ba and bei, allowing them to employ abstract syntactic representations in comprehending Mandarin transitive constructions. The findings demonstrate that children are sensitive early on to the structural information encoded in the constructions.

Word learning mechanisms

How do children acquire the meanings of words? Many word learning mechanisms have been proposed to guide learners through this challenging task. Despite the availability of rich information in the learner's linguistic and extralinguistic input, the word-learning task is insurmountable without such mechanisms for filtering through and utilizing that information. Different kinds of words, such as nouns denoting object concepts and verbs denoting event concepts, require to some extent different kinds of information and, therefore, access to different kinds of mechanisms. We review some of these mechanisms to examine the relationship between the input that is available to learners and learners' intake of that input-that is, the organized, interpreted, and stored representations they form. We discuss how learners segment individual words from the speech stream and identify their grammatical categories, how they identify the concepts denoted by these words, and how they refine their initial representations of word meanings. WIREs Cogn Sci 2017, 8:e1435. doi: 10.1002/wcs.1435 This article is categorized under: Linguistics > Language Acquisition Psychology > Language.

Preschoolers' Acquisition of Novel Verbs in the Double Object Dative

Children have difficulty comprehending novel verbs in the double object dative (e.g., Fred blicked the dog a stick) as compared to the prepositional dative (e.g., Fred blicked a stick to the dog). We explored this pattern with 3 and 4 year olds (N = 60). In Experiment 1, we replicated the documented difficulty with the double object frame, even though we provided more contextual support. In Experiment 2, we tested a novel hypothesis that children would comprehend novel verbs in, and generalize them to, the double object frame if they were first familiarized to the verbs in the prepositional frame. They did, suggesting that part of their difficulty with the double object frame is due to uncertainty about a new verb's semantic/syntactic properties, information that the easy-to-comprehend prepositional frame provides. The benefits of training were short-lived, however; children again struggled after a 2-h delay. The results are discussed in the context of mechanisms underlying verb acquisition.

The role of prosody in infants' early syntactic analysis and grammatical categorization

This study tested the hypothesis that phrasal prosody assists early syntactic acquisition. Stimulus-sentences consisting of French determiners and pseudo-lexical-words were ambiguous between two syntactic structures, e.g., [[TonDet felliAdj craleN]NP [vurV laDet gosineN]VP] versus [[TonDet felliN]NP [craleV vurPrep laDet gosineN]VP], which had distinct prosodic cues. French-learning 20-month-olds were familiarized with the sentences either in the prosody of one structure, or the other structure. All infants were tested with Det + N (e.g., LeDet craleN) versus Pron + V (e.g., TuPron cralesV) trials containing non-familiarized functors. Infants perceived the test-stimuli according to the familiarized structure. They used prosody to categorize words and interpret adjacent and non-adjacent syntactic dependencies.