Toddlers’ ability to learn new syntax-semantics links
Creators: name: Babineau, Mireille
name: Amarakoon, Anuki
Publisher: name: Open Science Framework
Year: 2022
Subjects: subject: Social and Behavioral Sciences

description: Toddlers’ ability to learn new syntax-semantics links Goal: To assess whether infants can rapidly associate novel function words to semantic categories, and whether the new function words will be later used by infants to narrow down the probable meanings of novel content words. Importantly, this study aims to assess whether an infant’s ability to learn and apply the association between novel syntactic contexts and semantic categories is limited by core knowledge. Since past work has found a bilingual advantage using an array of cognitive and linguistic tasks, the performance of bilingual and monolingual infants will be compared. Introduction: By as young as 18 months, infants are able to use grammar to guide the acquisition of word meanings. This mechanism is called syntactic bootstrapping. To be able to exploit syntax in this way, an infant must be able to identify the semantic information that a syntactic context provides. Syntactic contexts are mostly formed of function words (i.e., “the”, “a”, “she”, “he”), which can be exploited during early semantic acquisition, because they provide useful information about co-occurring content words and are heard frequently enough that they are known early in development. Studies have shown that before the age of one infants recognize the function words of their native language (e.g., in English: Shi et al., 2006; in French: Shi &amp; Lepage, 2008) and they are sensitive to the co-occurrence patterns between function words and common content words (Babineau &amp; Christophe, 2022). What still remains up for debate is the process in which a child learns the power of grammatical structures, particularly the syntactic contexts which correspond to a given semantic feature. The semantic seed hypothesis (e.g., Christophe et al., 2016) attempts to settle this debate, postulating that children learn the associations between syntactic contexts and semantics by generalizing from a few words which they know the meanings of. These few words are considered to be semantic seeds; children are thought to track the syntactic context of semantic seeds and infer that other words which appear in the same syntactic context share certain properties. This theory is supported not only by computational work (Brusini, et al., 2021), but also experimentally (Babineau, et al., 2021), displaying that children can discover the predictiveness of novel function words by tracking the immediate context of familiar words and can quickly apply the novel grammatical elements to learn the meaning of new words. Prior studies investigating the role of semantic seeds in syntactic bootstrapping have limitations. Specifically, previous work by Barbir et al., (under review) utilized novel determiners (‘ko’ for animates and ‘ka’ for inanimates) to indicate a categorical distinction between animates and inanimates. The chosen categories may have played a role in its ease of learning as the distinction between animates and inanimates is considered to be a part of ‘core knowledge.’ Within the first 6 months of life, preverbal infants use various cues in order to classify objects as being animate versus inanimate, and aspects of the representation of animacy appear to be embedded into the adult visual system as well. Animacy is highly salient to both children and adults, and therefore syntactic units related to animacy are hypothesized to be easier to learn.These learning and processing biases are thought to become embedded in language structure in the form of morphological and syntactic statistical regularities (Strickland, 2017). Researchers have observed a pattern across many languages, in which basic (i.e., more general) categories within language reflect conceptual divides present in core knowledge. The current study therefore aims to test the hypothesis that core knowledge distinctions are easier to map onto morphosyntactic markers than non-core knowledge distinctions. We aim to assess whether the word learning mechanism described by the semantic seed hypothesis is limited by core knowledge or if, alternatively, children can easily learn to associate novel function words to any conceptual distinction. Considering the aims of this study, it is important to not only evaluate the performance of monolingual infants, but also bilingual infants. Bilingual infants have displayed an advantage when it comes to language acquisition, in comparison to their monolingual peers. Various studies (e.g. Kaushanskaya &amp; Marian, 2009; Singh, Fu, Tay, &amp; Golinkoff, 2017; Warmington, Kandru-Pothineni &amp; Hitch, 2019) have demonstrated that an understanding of two or more languages facilitates some aspects of language learning. For example, Singh, Poh and Fu (2016) found that while monolingual infants were only able to map tone distinctions at 17-18 months, bilingual infants demonstrated precocity in their ability to integrate tone variation in a language-selective manner as early as 12–13 months. Similarly, Singh et al., (2018) found that bilingual infants were sensitive to different similar sounding words that vary in vowel quality, whereas monolingual English-learning infants were not, suggesting that sensitivity to some phonemic distinctions may be enhanced by bilingual exposure. Studies looking at adults’ ability to find statistical patterns in artificial languages have also found a bilingual advantage (Wang &amp; Saffran, 2014; Poepsel &amp; Weiss, 2016) ). Considering the prior research, it would be valuable to assess if bilingual infants, uniquely, display an ability to learn new morphosyntactic cues and utilize these cues to learn novel words in a way that is not limited by core knowledge. That is, can bilingual infants learn to associate novel function words to conceptual distinctions that monolingual infants cannot? The Hypothesis: The current project aims to test whether infants can rapidly associate novel syntactic contexts to semantic categories, and whether the learning mechanism used to grasp this association is limited by core knowledge. We expect that the participants of this study will successfully categorise animates and inanimates (a core knowledge distinction) using the newly acquired determiners (“ko” and “ka”), considering that prior research (Barbir et al., 2019) utilizing a similar methodology has obtained such a result. However, based on previous literature focused on cross-linguistic regularities (ex. Strickland, 2017), it is hypothesized that infants will succeed in learning novel syntactic contexts predicting semantic categories which reflect core knowledge distinctions only, such that the word learning mechanism described by the semantic seed hypothesis is limited by core knowledge. If, alternatively, infants display the ability to correctly categorise novel words belonging to a novel core knowledge and a novel non-core knowledge category using the newly acquired determiner, the study’s results would suggest that an infant’s ability to learn new morphosyntactic cues is not limited by core knowledge and ultimately display the power and flexibility of an infant’s ability to learn and apply syntax-semantic links to bolster their lexical development. Prior research suggests that bilingual infants have an advantage when it comes to language acquisition, compared to their monolingual peers. Bilingual infants may therefore display the ability to categorise novel words belonging to the core knowledge category and the non-core knowledge category, while monolinguals are only able to correctly categorise novel words belonging to the core knowledge category. If this hypothesis is correct, this study would serve as compelling evidence of the strong advantage bilingualism serves in language acquisition. Experiment: In the present study we will test whether the word learning mechanism described by the semantic seed hypothesis is limited by core knowledge by investigating an infant’s ability to learn novel noun class systems, one marking a core knowledge category (i.e. animates vs. inanimates) and another marking a non-core knowledge category (i.e. vehicles vs. non-vehicles). French-learning monolingual and bilingual toddlers will be randomly assigned to either the vehicle (non-core knowledge) condition or the animacy (core knowledge) condition. The training phase of the experiment is centered around training videos depicting a woman playing with toys, speaking in child-directed speech and replacing the determiners un/une ('a') and le/la ('the') by 'ko', in cases involving animates or vehicles (depending on the condition) and 'ka', in cases involving non-vehicular inanimate objects. During the study’s test phase, two novel visual stimuli (two pairs involving a novel animate and non-vehicular inanimate in the animacy condition; two pairs involving a novel vehicle and non-vehicular inanimate in the vehicle condition) will be presented alongside a prompting sentence, encouraging infants to look at one of the two images (e.g. “look at ko bamoule!”). The prompting sentence will include one of the novel determiners (‘ko’ or ‘ka’) presented to infants in the training video. If infants accurately learned the predictiveness of the novel determiners during training (e.g. ko+vehicles and ka+non-vehicles in the vehicle condition), they should be able to use this categorisation to narrow down the potential meaning of the novel words (e.g., ko+bamoule, bamoule = vehicle) and consequently look to the appropriate novel item. If the toddlers can successfully link semantic properties of known words to the surrounding syntactic contexts in both the animacy and vehicle condition, our study would suggest that the semantic seed hypothesis is not limited by core-knowledge. Method Participants: We will recruit approximately 128 infants from the lab database, who are 19 to 21 months old, wherein approximately half of the infants are bilingual (French and another language) and the other half are monolingual French-learning infants. In each condition, 32 monolingual and 32 bilingual infants will participate. Since appointments will not be cancelled, the final sample might be larger. All invited participants are screened beforehand according to the following inclusion criteria: infants must have no known hearing or vision limitation, infants must be born full-term (after 37 weeks of gestation), and have no known developmental disorder. All monolingual infants must have heard less than 10% of another language, whereas bilingual infants are required to be exposed to at least 30% to their second language. The exclusion criteria are as follows: failure to respond correctly to the two training test trials, failure to respond correctly to more than 50% of the trials with familiar words, less than two usable test trials (trials with more than 25% missing eye-tracker data are excluded from analyses), fussiness during the experiment, crying, interference of parents during the task, and not having watched the training video at home for 3 days consecutively. Both monolingual and bilingual infants will be randomly assigned to either the vehicle condition or the animacy condition before the training phase. This main study will follow a preliminary study with the same experimental protocol, but with an adult participant sample of approxiately 96 individuals (24 monolinguals in both conditions (total N=48), 24 bilinguals in both conditions (total N=48). With regards to the adult sample, participants will complete the Language and Social Background Questionnaire (Anderson et al., 2018) as well as a post-experiment debriefing questionnaire. The debriefing questionnaire contains open questions regarding the goal of the study (inquiring if the participants came to understand the meaning of the novel words ‘ko’ and ‘ka’) as well as multiple choice questions about the content of the training video (to ensure participants’ attention during this crucial part of the experiment). As with the infant eye tracking data, any trial with more than 25% of eye tracking data missing will be excluded. If more than half of the test trials involving the novel words are excluded (total of 8), then we will exclude the participant altogether. Materials: Novel Determiners: The novel determiners ko (/ko/) and ka (/ka/) were selected as they are phonotactically possible in French and resemble existent singular French determiners, which are monosyllabic and have roughly similar phonological forms for masculine and feminine variants. Training Videos: There are two distinct training videos; one video is exclusively displayed to participants randomly assigned to the animacy condition and one video is exclusively displayed to participants randomly assigned to the vehicle condition. During both the animacy and vehicle specific training videos, the storyline is identical; A woman is acting out stories with stuffed animals, vehicles and toy objects, using child-directed speech and French lexicon, except for the novel determiners. In both training videos, the novel determiners are each presented 30 times (ko x 30, ka x 30), but the words co-occurring with ‘ko’ vary. In the training video specific to the animacy condition, /ko/ is paired with six distinct animal nouns (lapin rabbit, poule chicken, chien dog, chat cat, souris mouse, grenouille frog) and /ka/ is paired with six distinct object nouns (livre book, biberon bottle, balle ball, manteau jacket, téléphone phone, chapeau hat) that French-learning infants are likely to know by 20 months of age based on previous CDI reports. The nouns were chosen such that half of the animal nouns were masculine and half feminine, and the same for object nouns. As such, the novel determiners could not be marking grammatical gender. The novel determiners functioned in the same way structurally as existent determiners. For example, adjectives in French appear most often between the determiner and noun (e.g., le joli chat, the cute cat). This was thus replicated with the novel determiners: ko joli chat. Infants heard each determiner paired with each corresponding noun 6 times (e.g., ka biberon), and one of the six times the pairing involved an adjective (e.g., ka gros biberon). The adjective pairing also served to facilitate segmentation of the determiner-noun sequence, such that the determiner-noun combination would not be perceived as one new noun (e.g., ka biberon) or a proper noun. In the training video specific to the vehicle condition, the content remained identical to that of the animacy condition, except that /ko/ is paired with six distinct vehicle-related nouns (voiture car, tracteur tractor, camion truck, moto motorcycle, train train, poussette stroller). In an attempt to maintain as much consistency as possible between the two training videos, “ka” is paired with the same familiar nouns used in the animacy condition (livre book, biberon bottle, balle ball, manteau jacket, téléphone phone, chapeau hat), as the inanimate objects also serve as non-vehicular objects. Moreover, in both videos, the storyline and the toys included in the video are identical (see Figure 1). Infants who view the training videos witness a woman acting out stories with stuffed animals, vehicles and toy objects, using child-directed speech and French lexicon, except for the novel determiners. In the animacy condition, the vehicles (e.g. car) are never labeled (the pronouns il/elle ‘it’ and ça ‘this/that’ are used instead). In the vehicle condition, pronouns are used and the animals are never labelled. Thus, key characteristics within the two videos are controlled, so that both videos are as similar as possible in terms of their content. Test Items: During the test phase, the participants will see two pictures presented side-by-side while they hear sentences containing a novel pseudo-noun preceded by either “ko” or “ka”. The test items are presented within a preferential looking paradigm, wherein the audio presents a novel determiner and a noun and the visual stimuli present a target image and a distractor. To familiarise infants with the testing procedure, just prior to the first test trial with a novel word, infants will experience two training/filler trials in the same format, however, the corresponding audio and visual stimuli will have been previously presented during the training video. The trials which follow include test trials and ‘filler’ trials. The test trials place four novel words after “ko” and “ka”, with each novel word tested twice for a total of 8 test trials. Interspersed between the novel word test trials will be 8 filler trials so that an infant will never see two test trials sequentially. There will be two different kinds of filler trials; four ‘seen’ trials and four ‘known’ trials. ‘Seen’ filler trials include nouns presented in the training video paired with a new visual exemplar of the noun. In the animacy condition, infants will thus see a different mouse, cat, bottle, and hat from those seen during the training video. Similarly, in the vehicle condition, infants will see a different car, train, bottle, and hat from those seen in the training video. The known trials include nouns that were not present during the training video but are likely to be known by 20-month-old infants based on previous CDI reports. For the animacy condition, the trials will include the nouns poisson fish, cheval horse, chaussure shoe, and chaise chair. For the vehicle condition, the trials will include the nouns bus bus, vélo bike, chaussure shoe, and chaise chair. The order and presentation of the trials were carefully counterbalanced across the sample, with 8 groups created. The side of the target stimulus (left vs right) is randomized by the Matlab script used to run the study. Novel nouns and images: During the test phase, the novel determiners /ko/ and /ka/ are presented with one of four novel nouns (bamoule /bamul/, pirdale /piʁdal/, doripe /doʁip/, bradole /bʁadɔl/). Novel nouns were created such that they are phonotactically possible in French. The sound of a given determiner (“ko” or “ka”) paired with each novel noun is associated with a novel target image; either an animal or object in the animacy condition and either a vehicle or a non-vehicle object in the vehicle condition. Novel animal images depicted a pink stuffed animal with a big head and many short feet, and a mouse-like animal with rabbit ears and an anteater’s trunk, the novel inanimate object images were a round colourful xylophone-like musical toy and a standing top, and the novel vehicle images were a toy resembling a wheelbarrow and a toy resembling a forklift. Four sets of pairings between the novel nouns and the associated novel images were constructed for both the animacy condition’s test phase and the vehicle condition’s test phase, so as to control for item effects; each novel noun and each novel image were paired equally across all the sequences of pairings in the animacy condition as well as the vehicle condition. In half of the sequences /ko/ appeared with the novel words, and in the other half of the sequences /ka/ appeared with the novel words, such that across all the sequences /ko/ and /ka/ were paired with all novel words equally. An equal number of the children will be randomly assigned to each kind of pairing word-object. This will be done to control for any possible effect that a given stimulus, or the combination of a set of stimuli could have on the measured variables. Data Collection Procedures: We will first conduct the experiment with approximately 96 adults, wherein half the sample is considered to be monolingual and the other half of the sample is considered to be bilingual. If the experimental design is successful, we will then conduct the experiment with a sample of 128 19- to 20-month old infants, wherein half the sample is considered to be monolingual and the other half of the sample is considered to be bilingual. Adult Procedure: The procedure will be identical to that of the infants, as described below, except for one differing factor. First, adults will only see the training video once, in the lab before the test phase. Infant Procedure: Before coming to the lab for the test phase, parents will be asked to ensure their child watches the training video at home, once a day, for three consecutive days. Parents will be instructed to be as neutral and quiet as possible during the screenings and not to refer to the video after the screening. The day before coming to the lab, parents will be asked to fill out a short online questionnaire indicating whether the infant had seen all three videos from beginning to end. Parents will also be asked to fill out the French version of the MacArthur Communicative Development Inventory, so as to gauge each infant's vocabulary range. After watching the training video over the three days, infants will complete the test phase at the Babylab. During testing, infants will be sitting on their caregiver’s lap at a distance of 65cm from a 42’ screen. Caregivers will be asked to wear headphones and listen to a neutral music-mix during the experiment. They will not be able to hear the stimuli presented to the infant. Gaze will be measured in two ways: the fine-grained ‘looking-while-listening’ method which encodes the evolution of gaze patterns from moment to moment during the trial, and the more broad ‘preferential looking’ method which sums overall gaze time to a target during the trial. The infant’s gaze will be recorded with an Eyelink 1000 eye-tracker at a frequency of 500 Hz. Infants will first view a short video presenting the novel toys. The test phase will follow, in which infants will be presented with two images on the screen, one on the left-most side of the screen and one on the right. For infants in the animacy condition, each test phase trial will display one animate and one inanimate image. For infants in the vehicle condition, each test phase trial will display one vehicle image (distinguished by the presence of wheels) and one image of a non-vehicular object (synonymous with inanimate images). Images will be presented for 3s one at a time, with a prompting sentence to attract their attention (i.e. Tu vois ça? “Do you see that?”, Oh regarde! “Oh look”), then the two pictures will be presented on the screen and a prompting sentence will begin to play, asking the child to look at one of the two images (i.e. Oh regarde, ko bamoule! Tu vois? Ko bamoule! “Oh look, ko bamoule! Do you see? Ko bamoule!”). All participants will hear the same prompting sentences containing one of the novel determiners (“ko” or “ka”), along with one of four novel nouns created to be phonotactically possible in French (‘bamoule’, ‘doripe’, ‘pirdale’, ‘bradole’). The first determiner will be heard at 3.750s and the second determiner will be heard at 6.250. Each of the 18 trials will last 9s. The experiment is expected to last approximately 12 minutes. Manipulated/independent variables: We will manipulate the presence of /ko/ (associated with animates or vehicles depending on the condition) or /ka/ (associated with inanimates or non-vehicular objects depending on the condition) in the test phase to observe to preferential looking behaviours of infants and evaluate if said behaviours vary in accordance with the presentation of the novel determiners. Measured/dependent variables: For the main study using the infant sample, the dependent variable for analysis will be the time infants spend looking at the images in the test trials. For each participant in this experiment, we will measure the time course of their eye-gaze during each test trial. Because the proportion of looks toward the pictures depicting an animate and inanimate (and similarly a vehicle and non-vehicle) in this experiment are complementary (with exception of time spent looking away), in our analysis we will consider the proportion of looks toward the picture showing an animate or the vehicle (depending on the condition) as the dependent variable. Analysis plan: The data obtained from participants in the animacy condition and the vehicle condition will be evaluated separately according to the outline below. We plan to analyze the proportion of gaze to the novel animate image and novel vehicle image (depending on the condition) when infants hear a prompting sentence with “ko” compared to one with “ka.” If infants can categorise and use the novel determiners to narrow down the meanings of the novel nouns they do not know, they should show distinct gaze patterns for novel nouns paired with “ko” and for those paired with “ka.” We will first conduct a cluster-based permutation analysis (Maris &amp; Oostenveld, 2007) on this data to find the time-window(s) where a significant effect of determiner (ko/ka) is observed (predefined threshold (t = 1.5), indicating that infants looked more to the image depicting an animal (in the animacy condition) or a vehicule (in the vehicule condition) while hearing a new word following “ko” than when hearing a new word following “ka”. We will also compare looking times for the duration of the entire trials by using a paired sample t-test conducted on the average overall looking time per participant. This study is a follow up study to Barbir et al. (2019), with the methodology being extended to evaluate whether infants can learn new semantic categories which predict non-core knowledge related distinctions as well as core knowledge related distinctions. With this in mind, the study conducted by Barbir and her colleagues identified a distinct time-window(s) wherein a significant effect of condition was observed within the eye-tracking data. Specifically, a cluster-based permutation analysis revealed that infants looked more to the animate image when they heard /ko/ than when they had heard /ka/ during the time-window from 300 to 2440ms after hearing the novel determiners. Considering that the methodology of the the Barbir et al. study mirrors that of the current study (with the exception of the additional vehicle condition), it is reasonable to expect infants in the current study to look significantly more to the animate/vehicle image when they heard /ko/ than when they had heard /ka/ during said time-window. We will therefore focus on a 2s time-window starting from 4.050s to 6.050s during the test trials to evaluate if a significant effect of condition is observed, indicating that infants look more to the picture presenting an animate/vehicle while hearing a new word following /ko/ (i.e., preceding animates/vehicles in the training sentences) than when it follows /ka/ (i.e., preceding inanimates/non-vehicles in the training sentences).