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Toddlers are sensitive to the reliability of speakers in their environment \cite{koenig2010}.While previous work suggests that children prefer labels from reliable speakers, it remains unclear how these social representations guide lower-level information-seeking processes that affect speaker preferences. The current study introduces a gaze-contingent eye-tracking paradigm to investigate how children engage in sampling during word learning. Toddlers (22-24m) view videos of two speakers labeling familiar objects; one speaker provides reliable labels and the other speaker provides unreliable labels. Toddlers then sample novel labels from the speakers using a gaze-contingent interface: only the speaker they are fixating on provides a novel label. Preliminary data (N = 18) suggests that participants prefer to sample first from the reliable speaker over the unreliable speaker. However, there is little difference in overall sampling preferences. Our findings suggest that toddlers can assess speaker reliability, but remain open to exploring information from unreliable speakers.

To efficiently learn new words, children use constraints such as mutual exclusivity (ME) to narrow the search for potential referents. The current study investigated the use of ME in toddlers with autism spectrum disorder (ASD) and neurotypical (NT) peers matched on nonverbal cognition. Thirty-two toddlers with ASD and 26 NT toddlers participated in a looking-while-listening task. Images of novel and familiar objects were presented along with a novel or familiar label. Overall, toddlers with ASD showed less efficient looking toward a novel referent when a novel label was presented compared to NT toddlers, controlling for age and familiar word knowledge. However, toddlers with ASD and higher language ability demonstrated more robust use of ME than those with lower language ability.

Language comprehension involves cognitive abilities that are specific to language as well as cognitive abilities that are more general and involved in a wide range of behaviors. One set of domain-general abilities that support language comprehension are executive functions (EFs), also known as cognitive control. A diverse body of research has demonstrated that EFs support language comprehension when there is conflict between competing, incompatible interpretations of temporarily ambiguous words or phrases. By engaging EFs, children and adults are able to select or bias their attention toward the correct interpretation. However, the degree to which language processing engages EFs in the absence of ambiguity is poorly understood. In the current experiment, we tested whether EFs may be engaged when comprehending speech that does not elicit conflicting interpretations. Different components of EFs were measured using several behavioral tasks and language comprehension was measured using an eye-tracking procedure. Five-year-old children (n = 56) saw pictures of familiar objects and heard sentences identifying the objects using either their names or colors. After a series of objects were identified using one dimension, children were significantly less accurate in fixating target objects that were identified using a second dimension. Further results reveal that this decrease in accuracy does not occur because children struggle to shift between dimensions, but rather because they are unable to predict which dimension will be used. These effects of predictability are related to individual differences in children's EFs. Taken together, these findings suggest that EFs may be more broadly involved when children comprehend language, even in instances that do not require conflict resolution.

How do learners gather new information during word learning? One possibility is that learners selectively sample items that help them reduce uncertainty about new word meanings. In a series of cross-situational word learning tasks with adults and children, we manipulated the referential ambiguity of label-object pairs experienced during training and subsequently investigated which words participants chose to sample additional information about. In the first experiment, adult learners chose to receive additional training on object-label associations that reduce referential ambiguity during cross-situational word learning. This ambiguity-reduction strategy was related to improved test performance. In two subsequent experiments, we found that, at least in some contexts, children (3-8 years of age) show a similar preference to seek information about words experienced in ambiguous word learning situations. In Experiment 2, children did not preferentially select object-label associations that remained ambiguous during cross-situational word learning. However, in a third experiment that increased the relative ambiguity of two sets of novel object-label associations, we found evidence that children preferentially make selections that reduce ambiguity about novel word meanings. These results carry implications for understanding how children actively contribute to their own language development by seeking information that supports learning.

Language acquisition depends on the ability to detect and track the distributional properties of speech. Successful acquisition also necessitates detecting changes in those properties, which can occur when the learner encounters different speakers, topics, dialects, or languages. When encountering multiple speech streams with different underlying statistics but overlapping features, how do infants keep track of the properties of each speech stream separately? In four experiments, we tested whether 8-month-old monolingual infants (N = 144) can track the underlying statistics of two artificial speech streams that share a portion of their syllables. We first presented each stream individually. We then presented the two speech streams in sequence, without contextual cues signaling the different speech streams, and subsequently added pitch and accent cues to help learners track each stream separately. The results reveal that monolingual infants experience difficulty tracking the statistical regularities in two speech streams presented sequentially, even when provided with contextual cues intended to facilitate separation of the speech streams. We discuss the implications of our findings for understanding how infants learn and separate the input when confronted with multiple statistical structures.

How do learners gather new information during wordlearning? We present evidence that adult learners will chooseto receive additional training on object-label associations thatreduce ambiguity about reference during cross-situationalword learning. This ambiguity-reduction strategy is related toimproved test performance. We find mixed evidence thatchildren (4-8 years of age) show a similar preference to seekinformation about words experienced in ambiguous wordlearning situations. In an initial experiment, children did notpreferentially select object-label associations that remainedambiguous during cross-situational word learning. However,this may be explained by some children having relatively highcertainty about object-label associations for which they didnot see evidence disconfirming their initial hypothesis. In asecond experiment that increased the relative ambiguity oftwo sets of novel object-label associations, we found evidencethat children preferentially make selections that reduceambiguity about novel word meanings.

Non-adjacent dependencies are ubiquitous in language, butdifficult to learn. Previous research has shown that the presenceof high variability between dependent items facilitateslearning. Yet what allows learning of non-adjacentdependencies even without high variability in interveningelements? One possibility is that learning non-adjacentdependencies highlights similar structures, allowing people tolearn new non-adjacent dependencies that are otherwisedifficult. In two studies, we show how being exposed tolearnable non-adjacent dependencies can change learners’sensitivity to novel non-adjacent regularities that are moredifficult to detect. These findings demonstrate a new way inwhich learning can build on and shape later learning aboutcomplex linguistic structure.

Adults typically struggle to perceive non-native sound contrasts, especially those that conflict with their first language. Do the same challenges persist when the sound contrasts overlap but do not conflict? To address this question, we explored the acquisition of lexical tones. While tonal variations are present in many languages, they are only used contrastively in tonal languages. We investigated the perception of Mandarin tones by adults with differing experience with Mandarin, including naïve listeners, classroom learners, and native speakers. Naïve listeners discriminated Mandarin tones at above-chance levels, and performance significantly improved after just one month of classroom exposure. Additional evidence for plasticity came from advanced classroom learners, whose tonemic perception was indistinguishable from that of native speakers. The results suggest that unlike many other non-native contrasts, adults studying a language in the classroom can readily acquire the perceptual skills needed to discriminate Mandarin tones.

This study investigated whether children with autism spectrum disorder (ASD) are sensitive to mispronunciations of familiar words and compared their sensitivity to children with typical-development. Sixty-four toddlers with ASD and 31 younger, typical controls participated in a looking-while-listening task that measured their accuracy in fixating the correct object when it was labelled with a correct pronunciation versus mispronunciation. A cognitive style that prioritizes processing local, rather than global features, as claimed by the weak central coherence theory, predicts that children with ASD should be more sensitive to mispronunciations than typical controls. The results, however, reveal no differences in the effect of mispronunciations on lexical processing between groups, even when matched for receptive language or non-verbal cognitive skills.

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.

In typical development, listeners can use semantic content of verbs to facilitate incremental language processing--a skill that is associated with existing language skills. Studies of children with ASD have not identified an association between incremental language processing in semantically-constraining contexts and language skills, perhaps because participants were adolescents and/or children with strong language skills. This study examined incremental language processing and receptive language in young children with ASD with a range of language skills. Children showed a head start when presented with semantically-constraining verbs (e.g., "Read the book") compared to neutral verbs (e.g., "Find the book"). Children with weaker receptive language showed a smaller head start than children with stronger receptive language skills, suggesting continuity between typical development and ASD.

Domain‐general prediction differences have been posited as underlying many aspects of the cognitive‐behavioral profile in autism. An interesting potential implication of such differences is hyperplasticity of learning—the idea that autistic individuals may privilege more recent input over the accumulation of prior learning. Because real world language input is highly variable, hyperplasticity could have serious ramifications for language learning. To investigate potential hyperplasticity during a language processing task, we administered an experimental anticipatory eye movement (AEM) task to 2‐ to 3‐year‐old autistic children and neurotypical (NT) peers. Autistic children's change in anticipation from before to after a switch in contingencies did not significantly differ from NT counterparts, failing to support claims of hyperplasticity in the linguistic domain. Analysis of individual differences among autistic children revealed that cognitive ability was associated with prediction of the initial, stable contingencies, but neither age nor receptive language related to task performance. Results are discussed in terms of clinical implications and the broader context of research investigating prediction differences in autism. Lay Summary: Autistic individuals may differ from neurotypical peers when making predictions, especially when the environment is unstable. In this study, we found that 2‐ to 3‐year‐old autistic children's linguistic predictions did not differ from their neurotypical peers, though autistic children with stronger cognitive ability were better at prediction in stable environments. More research will be needed to investigate the relationship of prediction and language skills in autistic individuals. [ABSTRACT FROM AUTHOR]

Test‐retest reliability—establishing that measurements remain consistent across multiple testing sessions—is critical to measuring, understanding, and predicting individual differences in infant language development. However, previous attempts to establish measurement reliability in infant speech perception tasks are limited, and reliability of frequently used infant measures is largely unknown. The current study investigated the test‐retest reliability of infants' preference for infant‐directed speech over adult‐directed speech in a large sample (N = 158) in the context of the ManyBabies1 collaborative research project. Labs were asked to bring in participating infants for a second appointment retesting infants on their preference for infant‐directed speech. This approach allowed us to estimate test‐retest reliability across three different methods used to investigate preferential listening in infancy: the head‐turn preference procedure, central fixation, and eye‐tracking. Overall, we found no consistent evidence of test‐retest reliability in measures of infants' speech preference (overall r = 0.09, 95% CI [−0.06,0.25]). While increasing the number of trials that infants needed to contribute for inclusion in the analysis revealed a numeric growth in test‐retest reliability, it also considerably reduced the study's effective sample size. Therefore, future research on infant development should take into account that not all experimental measures may be appropriate for assessing individual differences between infants. Research Highlights: We assessed test‐retest reliability of infants' preference for infant‐directed over adult‐directed speech in a large pre‐registered sample (N = 158).There was no consistent evidence of test‐retest reliability in measures of infants' speech preference.Applying stricter criteria for the inclusion of participants may lead to higher test‐retest reliability, but at the cost of substantial decreases in sample size.Developmental research relying on stable individual differences should consider the underlying reliability of its measures. [ABSTRACT FROM AUTHOR]

Toddlers prefer to learn from familiar adults, particularly their caregivers, and perform better on word learning tasks when taught by caregivers than by strangers. However, it remains unclear why toddlers learn better from caregivers than from strangers. One possibility is that toddlers are more receptive to learning from individuals whom they have found to be engaging in previous interactions. The current study tested whether toddlers learn more from an unfamiliar adult who was previously engaging than from an unfamiliar adult who was previously unengaging. Toddlers (27–29 months, N = 40) were taught labels for novel objects by two different experimenters. Prior to word learning, toddlers watched pre‐recorded videos of one experimenter utilizing engaging behaviors (i.e., using infant‐directed speech, gestures, eye contact, and positive affect) and one experimenter utilizing unengaging behaviors (i.e., using adult‐directed speech, no gestures, no eye contact, and neutral affect). Both experimenters were equally engaging during labeling. Word learning was then tested using a looking‐while‐listening paradigm. The results of linear mixed‐effects model, cluster‐based permutation, and growth curve analyses suggest heightened performance for words that were taught by the experimenter who was previously engaging. These results begin to reveal the kinds of social experiences that promote success in early word learning. [ABSTRACT FROM AUTHOR]

How do infants become word meaning experts? This registered report investigated the structure of infants' early lexical representations by manipulating the typicality of exemplars from familiar animal categories. 14‐ to 18‐month‐old infants (N = 84; 51 female; M = 15.7 months; race/ethnicity: 64% White, 8% Asian, 2% Hispanic, 1% Black, and 23% multiple categories; participating 2022–2023) were tested on their ability to recognize typical and atypical category exemplars after hearing familiar basic‐level category labels. Infants robustly recognized both typical (d = 0.79, 95% CI [0.54, 1.03]) and atypical (d = 0.70, 95% CI [0.46, 0.94]) exemplars, with no significant difference between typicality conditions (d = 0.14, 95% CI [−0.08, 0.35]). These results support a broad‐to‐narrow account of infants' early word meanings. Implications for the role of experience in the development of lexical knowledge are discussed. [ABSTRACT FROM AUTHOR]

Williams syndrome (WS) is a rare genetic disorder associated with delays in language and cognitive development. The reasons for the language delay are unknown. Statistical learning is a domain-general mechanism recruited for early language acquisition. In the present study, we investigated whether infants with WS were able to detect the statistical structure in continuous speech. Eighteen 8- to 20-month-olds with WS were familiarized with 2min of a continuous stream of synthesized nonsense words; the statistical structure of the speech was the only cue to word boundaries. They were tested on their ability to discriminate statistically-defined "words" and "part-words" (which crossed word boundaries) in the artificial language. Despite significant cognitive and language delays, infants with WS were able to detect the statistical regularities in the speech stream. These findings suggest that an inability to track the statistical properties of speech is unlikely to be the primary basis for the delays in the onset of language observed in infants with WS. These results provide the first evidence of statistical learning by infants with developmental delays.

Infants acquiring their native language are adept at discovering grammatical patterns. However, it remains unknown whether these learning abilities are limited to language, or available more generally for sequenced input. The current study is a conceptual replication of a prior language study, and was designed to ask whether infants can track phrase structure-like patterns from nonlinguistic auditory materials (sequences of computer alert sounds). One group of 12-month-olds was familiarized with an artificial grammar including predictive dependencies between sounds concatenated into strings, simulating the basic structure of phrases in natural languages. A second group of infants was familiarized with a grammar that lacked predictive dependencies. All infants were tested on the same set of familiar strings vs. novel (grammar-inconsistent) strings. Only infants exposed to the materials containing predictive dependencies showed successful discrimination between the test sentences, replicating the results from linguistic materials, and suggesting that predictive dependencies facilitate learning from nonlinguistic input.

Learning the meanings of words involves not only forming connections between individual words and conceptsbut also building a network of connections across objects and words. Previous studies reveal that infants and adults can learnword-referent links across multiple ambiguous training instances by tracking the statistical co-occurrence of labels and objects(Smith & Yu, 2008; Dautriche & Chemla, 2014). We asked whether adults are sensitive to multiple types of statistical structurein these learning instances by manipulating the frequency with which objects co-occurred with each other during training trials.Across several studies (n=150), we find that adults not only learned to disambiguate label referents, but simultaneously formedconnections both between the frequently co-occurring objects themselves and between the labels of frequently co-occurringobjects. These findings indicate that learners exploit statistical regularities to form multiple types of associations during wordlearning.

Infants must develop both flexibility and constraint in their interpretation of acceptable word forms. The current experiments examined the development of infants' lexical interpretation of non-native variations in pitch contour. Fourteen-, 17-, and 19-month-olds (Experiments 1 and 2, N = 72) heard labels for two novel objects; labels contained the same syllable produced with distinct pitch contours (Mandarin lexical tones). The youngest infants learned the label-object mappings, but the older groups did not, despite being able to discriminate pitch differences in an object-free task (Experiment 3, N = 14). Results indicate that 14-month-olds remain flexible regarding what sounds make meaningful distinctions between words. By 17-19 months, experience with a nontonal native language constrains infants' interpretation of lexical tone.