Finding patterns and learning words: Infant phonotactic knowledge is associated with vocabulary size

Does bilingual experience influence statistical language learning?

Statistical language learning (SL) tasks measure different aspects of foreign language learning. Studies have used SL tasks to investigate whether bilingual experience confers advantages in acquiring additional languages through implicit processes. However, the results have been inconsistent, which may be related to bilingualism-related features (e.g., degree of dissimilarity between the specific language pair) and other variables such as specific processes that are targeted by the SL task. In the present study, we compared the performance of one Spanish monolingual and two bilingual (Spanish-Basque and Spanish-English) groups across three well-established SL tasks. Each task targeted a different aspect of foreign language learning; specifically, word segmentation, morphological rule generalization, and word-referent learning. In Experiment 1, we manipulated sub-lexical phonotactic patterns to vary the difficulty of three SL tasks, with the results showing no differences between the groups in word segmentation. In Experiment 2, we included non-adjacent dependencies to target affixal morphology rule learning, but again no group-related differences were found. In Experiment 3, we addressed word learning using an audio-visual SL task combining exclusive and multiple word-referent mappings, and found that bilinguals outperformed monolinguals, suggesting that bilingualism may exert influences on SL at the lexical level. This advantage might have been mediated by the high working memory demands required to perform the task. Summarizing, this study shows no evidence for a general bilingual advantage in SL, although bilinguals may outperform monolinguals under specific experimental conditions such as SL tasks that place high demands on working memory processes. In addition, the similar performance of Spanish-Basque and Spanish-English bilinguals across all three SL tasks suggests that the degree of dissimilarity between pairs of spoken languages does not modulate SL skills.

Novel phonotactic learning by children and infants: Generalizing syllable-position but not co-occurrence regularities

Restrictions in the sequencing of sounds (phonotactic constraints) can be represented at the level of sound co-occurrences (e.g., in baF.Pev, F and P co-occur) and at the level of the syllable (e.g., F is syllable-coda/end, P is syllable-onset/start). Can children (5-year-olds) and infants (11-month-olds) represent constraints as sound co-occurrences and/or relative to syllable positions? Participants listened to artificial languages displaying both word-medial consonant restrictions in co-occurrence pairs (e.g., FP or DZ but not FZ) and in the position of consonants within syllables (e.g., P/Z onsets and D/F codas) in words like baF.Pev and tiD.Zek. Children responded similarly to novel words with the same (e.g., FP) versus different (e.g., FZ) co-occurrence pairs, but they were more misled (i.e., responded "heard it before") by novel words with consonants in the same (e.g., onset-P) versus different (e.g., coda-P) syllable positions (Experiment 1). With the same training stimuli, infants had similar orientation times for novel words with the same versus different co-occurrence pairs, but they had longer orientation times for novel words with consonants in the same versus different syllable positions (Experiment 2). Thus, across different methods and ages, syllable-position information was more readily available for generalization than consonant co-occurrence information. The results suggest that when multiple regularities are present simultaneously, some phonotactic constraints (e.g., consonants in particular syllable positions) may be spontaneously represented and generalized by children and infants, whereas others (e.g., consonant co-occurrences) might not be available. The results contribute toward understanding how children and infants represent sound sequences.

Learning Words in Two Languages: Manipulating Exemplar Variability for Within- and Cross-Language Generalization

PURPOSE

This article aims to describe how exemplar variability can manipulate the word learning environment to maximize within- and cross-language generalization in Spanish-English bilinguals. Furthermore, we examined sources of individual variability that predicted word learning.

METHOD

Nineteen Spanish-English bilingual children participated in a word learning task presenting words in both languages. Children learned words either in a high variability condition (in which multiple exemplars are introduced with the target word) or in a no variability condition (in which the same referent is used with the target word). Word learning was tracked over the course of the training, and retention was examined once the training was discontinued. Children's generalization of referents within and across languages was also examined.

RESULTS

The exemplar variability effect was observed in within-language generalization trials, whereas cross-language generalization was less robust. Nevertheless, cross-language associations emerged in examining the role of language proficiency, such that semantic skills in English predicted word retention across languages. Similarly, children's propensity to code-switch during language production was positively correlated with retention of words learned in the high variability condition.

CONCLUSIONS

The findings show that Spanish-English bilingual children may make use of exemplar variability to support word learning in different ways compared with monolinguals. The exemplar variability effect interacts with children's acquired language skills and word learning abilities at the start of the intervention. This study provides preliminary evidence from which future research can develop word learning interventions that are responsive to the needs of multilinguals.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19241856.

Is there such a thing as a 'good statistical learner'?

A growing body of research investigates individual differences in the learning of statistical structure, tying them to variability in cognitive (dis)abilities. This approach views statistical learning (SL) as a general individual ability that underlies performance across a range of cognitive domains. But is there a general SL capacity that can sort individuals from 'bad' to 'good' statistical learners? Explicating the suppositions underlying this approach, we suggest that current evidence supporting it is meager. We outline an alternative perspective that considers the variability of statistical environments within different cognitive domains. Once we focus on learning that is tuned to the statistics of real-world sensory inputs, an alternative view of SL computations emerges with a radically different outlook for SL research.

Symbolic play provides a fertile context for language development

In this study, we test the hypothesis that symbolic play represents a fertile context for language acquisition because its inherent ambiguity elicits communicative behaviors that positively influence development. Infant-caregiver dyads (N = 54) participated in two 20-minute play sessions six months apart (Time 1 = 18 months, Time 2 = 24 months). During each session, the dyads played with two sets of toys that elicited either symbolic or functional play. The sessions were transcribed and coded for several features of dyadic interaction and language; infants' linguistic proficiency was measured via parental report. The two contexts elicited different communicative and linguistic behaviors. Notably, the symbolic play condition resulted in significantly greater conversational turn-taking than functional play, and also resulted in the greater use of questions and mimetics in infant-directed speech (IDS). In contrast, caregivers used more imperative clauses in functional play. Correlational and regression analyses showed that frequent properties of symbolic play (i.e., turn-taking, yes-no questions, mimetics) were positively related to infants' language proficiency, whereas frequent features of functional play (i.e., imperatives in IDS) were negatively related. The results provide evidence supporting the hypothesis that symbolic play is a fertile context for language development, driven by the need to negotiate meaning.

Boosting the input: 9-month-olds' sensitivity to low-frequency phonotactic patterns in novel wordforms

To learn their first words, infants must attend to a variety of cues that signal word boundaries. One such cue infants might use is the language-specific phonotactics to track legal combinations and positions of segments within a word. Studies have demonstrated that, when tested across statistically high and low phonotactics, infants repeatedly reject the low-frequency wordforms. We explore whether the capacity to access low-frequency phonotactic combinations is available at 9 months when pre-exposed to wordforms containing statistically low combinations of segments. Using a modified head-turn procedure, one group of infants was presented with nonwords with low-frequency complex onsets (dr-), and another group was presented with zero-frequency onset nonwords (dl-). Following pre-exposure and familiarization, infants were then tested on their ability to segment nonwords that contained either the low- or the zero-frequency onsets. Only infants in the low-frequency condition were successful at the task, suggesting some experience with these onsets supports segmentation.

Two for the price of one: Concurrent learning of words and phonotactic regularities from continuous speech

To acquire the words of their language, learners face the challenge of tracking regularities at multiple levels of abstraction from continuous speech. In the current study, we examined adults’ ability to track two types of regularities from a continuous artificial speech stream: the individual words in the speech stream (token level information), and a phonotactic pattern shared by a subset of those words (type level information). We additionally manipulated exposure time to the language to examine the relationship between the acquisition of these two regularities. Using a ratings test procedure, we found that adults can extract both the words in the language and their phonotactic patterns from continuous speech in as little as 3.5 minutes of listening time. Results from a 2AFC testing method provide converging evidence that adults rapidly learn both words and their phonotactic patterns. Together, the findings suggest that adults are capable of concurrently tracking regularities at multiple levels of abstraction from brief exposures to a continuous stream of speech.

When statistics collide: The use of transitional and phonotactic probability cues to word boundaries

Statistical regularities in linguistic input, such as transitional probability and phonotactic probability, have been shown to promote speech segmentation. It remains unclear, however, whether or how the combination of transitional probabilities and subtle phonotactic probabilities influence segmentation. The present study provides a fine-grained investigation of the effects of such combined statistics. Adults (N = 81) were tested in one of two conditions. In the Anchor condition, they heard a continuous stream of words with small differences in phonotactic probabilities. In the Uniform condition, all words had comparable phonotactic probabilities. In both conditions, transitional probability was stronger in words than in part-words. Only participants from the Anchor condition preferred words at test, indicating that the combination of transitional probabilities and subtle phonotactic probabilities may facilitate speech segmentation. We discuss the methodological implications of our findings, which demonstrate that even small phonotactic variations should be accounted for when investigating statistical speech segmentation.

Exploring the "anchor word" effect in infants: Segmentation and categorisation of speech with and without high frequency words

High frequency words play a key role in language acquisition, with recent work suggesting they may serve both speech segmentation and lexical categorisation. However, it is not yet known whether infants can detect novel high frequency words in continuous speech, nor whether they can use them to help learning for segmentation and categorisation at the same time. For instance, when hearing "you eat the biscuit", can children use the high-frequency words "you" and "the" to segment out "eat" and "biscuit", and determine their respective lexical categories? We tested this in two experiments. In Experiment 1, we familiarised 12-month-old infants with continuous artificial speech comprising repetitions of target words, which were preceded by high-frequency marker words that distinguished the targets into two distributional categories. In Experiment 2, we repeated the task using the same language but with additional phonological cues to word and category structure. In both studies, we measured learning with head-turn preference tests of segmentation and categorisation, and compared performance against a control group that heard the artificial speech without the marker words (i.e., just the targets). There was no evidence that high frequency words helped either speech segmentation or grammatical categorisation. However, segmentation was seen to improve when the distributional information was supplemented with phonological cues (Experiment 2). In both experiments, exploratory analysis indicated that infants' looking behaviour was related to their linguistic maturity (indexed by infants' vocabulary scores) with infants with high versus low vocabulary scores displaying novelty and familiarity preferences, respectively. We propose that high-frequency words must reach a critical threshold of familiarity before they can be of significant benefit to learning.

Perception of sibilant-liquid phonotactic frequency in full-term and preterm infants

We examined full-term and preterm infants' perception of frequent and infrequent phonotactic pairings involving sibilants and liquids. Infants were tested on their preference for syllables with onsets involving /s/ or /ʃ/ followed by /l/ or /r/ using the Headturn Preference Procedure. Full-term infants preferred the frequent to the infrequent phonotactic pairings at 9 months, but not at either younger or older ages. Evidence was inconclusive regarding a possible difference between full-term and preterm samples; however, limitations on the preterm sample size limited our power to detect differences. Preference for the frequent pairing was not related to later vocabulary development.

Measuring Statistical Learning Across Modalities and Domains in School-Aged Children Via an Online Platform and Neuroimaging Techniques

Statistical learning, a fundamental skill to extract regularities in the environment, is often considered a core supporting mechanism of the first language development. While many studies of statistical learning are conducted within a single domain or modality, recent evidence suggests that this skill may differ based on the context in which the stimuli are presented. In addition, few studies investigate learning as it unfolds in real-time, rather focusing on the outcome of learning. In this protocol, we describe an approach for identifying the cognitive and neural basis of statistical learning, within an individual, across domains (linguistic vs. non-linguistic) and sensory modalities (visual and auditory). The tasks are designed to cast as little cognitive demand as possible on participants, making it ideal for young school-aged children and special populations. The web-based nature of the behavioral tasks offers a unique opportunity for us to reach more representative populations nationwide, to estimate effect sizes with greater precision, and to contribute to open and reproducible research. The neural measures provided by the functional magnetic resonance imaging (fMRI) task can inform researchers about the neural mechanisms engaged during statistical learning, and how these may differ across individuals on the basis of domain or modality. Finally, both tasks allow for the measurement of real-time learning, as changes in reaction time to a target stimulus is tracked across the exposure period. The main limitation of using this protocol relates to the hour-long duration of the experiment. Children might need to complete all four statistical learning tasks in multiple sittings. Therefore, the web-based platform is designed with this limitation in mind so that tasks may be disseminated individually. This methodology will allow users to investigate how the process of statistical learning unfolds across and within domains and modalities in children from different developmental backgrounds.

One language or two? Navigating cross-language conflict in statistical word segmentation

Bilingual infants must navigate the similarities and differences between their languages to achieve native proficiency in childhood. Bilinguals learning to find individual words in fluent speech face the possibility of conflicting cues to word boundaries across their languages. Despite this challenge, bilingual infants typically begin to segment and learn words in both languages around the same time as monolinguals. It is possible that early bilingual experience may support infants' abilities to track regularities relevant for word segmentation separately across their languages. In a dual speech stream statistical word segmentation task, we assessed whether 16-month-old infants could track syllable co-occurrence regularities in two artificial languages despite conflicting information across the languages. We found that bilingual, but not monolingual, infants were able to segment the dual speech streams using statistical regularities. Although the two language groups did not differ on secondary measures of cognitive and linguistic development, bilingual infants' real-world experience with bilingual speakers was predictive of their performance in the dual language statistical segmentation task.

Statistical Learning and Social Competency: The Mediating Role of Language

The current study sought to examine the contribution of auditory and visual statistical learning on language and social competency abilities as well as whether decreased statistical learning abilities are related to increased autistic traits. To answer these questions, participants' (N = 95) auditory and visual statistical learning abilities, language, social competency, and level of autistic traits were assessed. Although the relationships observed were relatively small in magnitude, our results demonstrated that visual statistical learning related to language and social competency abilities and that auditory learning was more related to autism symptomatology than visual statistical learning. Furthermore, the relationship between visual statistical learning and social competency was mediated by language comprehension abilities, suggesting that impairments in statistical learning may cascade into impairments in language and social abilities.

Phonological Learning Influences Label-Object Mapping in Toddlers

Purpose Infants rapidly acquire the sound patterns that characterize their native language. Knowledge of native language phonological cues facilitates learning new words that are consistent with these patterns. However, little is known about how newly acquired phonological knowledge-regularities that children are in the process of learning-affects novel word learning. The current experiment was designed to determine whether exposure to a novel phonological pattern affects subsequent novel word learning. Method Two-year-olds ( n = 41) were familiarized with a list of novel words that followed a simple phonotactic regularity. Following familiarization, toddlers were taught 4 novel label-object pairs. Two of the labels were consistent with the novel regularity, and 2 of the labels were inconsistent with the regularity. Results Toddlers with smaller vocabularies learned all of the novel label-object pairings, whereas toddlers with larger vocabularies only learned novel label-object pairings that were consistent with the novel phonological regularity. Conclusion These findings demonstrate that newly learned phonological patterns influence novel word learning and highlight the role of individual differences in toddlers' representations of candidate word forms.

Intersecting Constraints on Label Learning: Effects of Age, Label Properties, and Referential Context

This research investigates the development of constraints in word learning. Previous experiments have shown that as infants gain more knowledge of native language structure, they become more selective about the forms that they accept as labels. However, the developmental pattern exhibited depends greatly on the way that infants are introduced to the labels and tested. In a series of experiments, we examined how providing referential context in the form of familiar objects and familiar object names affects how infants learn labels that they would otherwise reject, nonspeech sounds. We found evidence of the development of intersecting constraints: Younger infants (14-month-olds) were more open to learning nonspeech tone labels than older infants (19-month-olds), and younger infants were more open to the influence of referential context. These findings suggest that infants form expectations about labels and labeling contexts as they become more sophisticated learners.

Do Infants Learn Words From Statistics? Evidence From English-Learning Infants Hearing Italian

Infants are sensitive to statistical regularities (i.e., transitional probabilities, or TPs) relevant to segmenting words in fluent speech. However, there is debate about whether tracking TPs results in representations of possible words. Infants show preferential learning of sequences with high TPs (HTPs) as object labels relative to those with low TPs (LTPs). Such findings could mean that only the HTP sequences have a word-like status, and they are more readily mapped to a referent for that reason. But these findings could also suggest that HTP sequences are easier to encode, just like any other predictable sequence. Here we aimed to distinguish between these explanations. To do so, we built on findings that infants become resistant to learning labels that are not typical of their native language as they approach 2 years of age and add words to their lexicons. If tracking TPs in speech results in identifying candidate words, at this age TPs may have reduced power to confer lexical status when they yield a unit that is very dissimilar to word forms that are typical of infants' native language. Indeed, we found that at 20 months, English-learning infants with relatively small vocabularies learned HTP Italian words (but not LTP words) as object labels, while infants with larger vocabularies resisted learning HTP Italian words. These findings suggest that the HTP sequences may be represented as candidate words, and more broadly, that TP statistics are relevant to word learning.

Distributional Cues to Language Learning in Children With Intellectual Disabilities

Purpose

In typical development, distributional cues-patterns in input-are related to language acquisition processes. Statistical and implicit learning refer to the utilization of such cues. In children with intellectual disability, much less is known about the extent to which distributional cues are harnessed in mechanisms of language learning.

Method

This tutorial presents what is known about the process of language learning in children with language impairments associated with different sources of intellectual disability: Williams syndrome, autism spectrum disorder, Down syndrome, and fragile X syndrome.

Results

A broad view is taken on distributional cues relevant to language learning, including statistical learning (e.g., transitional probabilities) and other patterns that support lexical acquisition (e.g., sensitivities to sound patterns, cross-situational word learning) or relate to syntactic development (e.g., nonadjacent dependencies).

Conclusions

Critical gaps in the literature are highlighted. Research in this area is especially limited for Down syndrome and fragile X syndrome. Future directions for taking learning theories into account in interventions for children with intellectual disability are discussed, with a focus on the importance of language input.

Infant statistical-learning ability is related to real-time language processing

Infants are adept at learning statistical regularities in artificial language materials, suggesting that the ability to learn statistical structure may support language development. Indeed, infants who perform better on statistical learning tasks tend to be more advanced in parental reports of infants' language skills. Work with adults suggests that one way statistical learning ability affects language proficiency is by facilitating real-time language processing. Here we tested whether 15-month-olds' ability to learn sequential statistical structure in artificial language materials is related to their ability to encode and interpret native-language speech. Specifically, we tested their ability to learn sequential structure among syllables (Experiment 1) and words (Experiment 2), as well as their ability to encode familiar English words in sentences. The results suggest that infants' ability to learn sequential structure among syllables is related to their lexical-processing efficiency, providing continuity with findings from children and adults, though effects were modest.