Seeing the Forest but Naming the Trees: An Object-Over-Place Bias in Learning Noun Labels.

Objects and places are foundational spatial domains represented in human symbolic expressions, like drawings, which show a prioritization of depicting small-scale object-shape information over the large-scale navigable place information in which objects are situated. Is there a similar object-over-place bias in language? Across six experiments, adults and 3- to 4-year-old children were asked either to extend a novel noun in a labeling phrase, to extend a novel noun in a prepositional phrase, or to simply match pictures. To dissociate specific object and place information from more general figure and ground information, participants either saw scenes with both place information (a room) and object information (a block in the room), or scenes with two kinds of object information that matched the figure-ground relations of the room and block by presenting an open container with a smaller block inside. While adults showed a specific object-over-place bias in both extending novel noun labels and matching, they did not show this bias in extending novel nouns following prepositions. Young children showed this bias in extending novel noun labels only. Spatial domains may thus confer specific and foundational biases for word learning that may change through development in a way that is similar to that of other word-learning biases about objects, like the shape bias. These results expand the symbolic scope of prior studies on object biases in drawing to object biases in language, and they expand the spatial domains of prior studies characterizing the language of objects and places.

EXPRESS: Speaker Variability, But Not Bilingualism, Influences Cross-Situational Word Learning.

When learning new words, listeners must contend with multiple sources of ambiguity and variability. Research has revealed that learners can resolve referential ambiguity by tracking co-occurrence statistics between words and their referents across multiple exposures over time - a process termed cross-situational word learning (XSWL). However, the degree to which variability in the input, such as input from multiple speakers, and variability in learner experience, such as bilingual language experience, modulate XSWL remain unclear. In the present study, we examined the effects of speaker variability in cross-situational word learning performance in monolingual adults and bilingual adults with a range of second language backgrounds and language acquisition histories. Results revealed above-chance word learning in both the single and the multiple speaker conditions across language groups. An advantage for word learning was observed in the single speaker condition but the effects of bilingual language experience were null. This research adds to the limited body of work dedicated to extending theories of statistical learning to account for variations in both input and learner characteristics as well as their interactions.

Learning a language with vowelless words.

Vowelless words are exceptionally typologically rare, though they are found in some languages, such as Tashlhiyt (e.g., fkt 'give it'). The current study tests whether lexicons containing tri-segmental (CCC) vowelless words are more difficult to acquire than lexicons not containing vowelless words by adult English speakers from brief auditory exposure. The role of acoustic-phonetic form on learning these typologically rare word forms is also explored: In Experiment 1, participants were trained on words produced in either only Clear speech or Casual speech productions of words; Experiment 2 trained participants on lexical items produced in both speech styles. Listeners were able to learn both vowelless and voweled lexicons equally well when speaking style was consistent for participants, but learning was lower for vowelless lexicons when training consisted of variable acoustic-phonetic forms. In both experiments, responses to a post-training wordlikeness ratings task containing novel items revealed that exposure to a vowelless lexicon leads participants to accept new vowelless words as acceptable lexical forms. These results demonstrate that one of the typologically rarest types of lexical forms - words without vowels - can be rapidly acquired by naive adult listeners. Yet, acoustic-phonetic variation modulates learning.

The role of morphology in novel word learning: a registered report.

The majority of the new words that we learn every day as adults are morphologically complex; yet, we do not know much about the role of morphology in novel word learning. In this study, we tackle this issue by comparing the learning of: (i) suffixed novel words (e.g. flibness); (ii) novel words that end in non-morphological, but frequent letter chunks (e.g. fliban); and (iii) novel words with non-morphological, low-frequency endings (e.g. flibov). Words are learned incidentally through sentence reading, while the participants' eye movements are monitored. We show that morphology has a facilitatory role compared with the other two types of novel words, both during learning and in a post-learning recognition memory task. We also showed that participants attributed meaning to word parts (if flibness is a state of happiness, then flib must mean happy), but this process was not specifically triggered by the presence of a suffix (flib must also mean happy in fliban and flibov), thus suggesting that the brain tends to assume similar meanings for similar words and word parts.

Auditory associative word learning in adults: The effects of musical experience and stimulus ordering.

Evidence for sequential associative word learning in the auditory domain has been identified in infants, while adults have shown difficulties. To better understand which factors may facilitate adult auditory associative word learning, we assessed the role of auditory expertise as a learner-related property and stimulus order as a stimulus-related manipulation in the association of auditory objects and novel labels. We tested in the first experiment auditorily-trained musicians versus athletes (high-level control group) and in the second experiment stimulus ordering, contrasting object-label versus label-object presentation. Learning was evaluated from Event-Related Potentials (ERPs) during training and subsequent testing phases using a cluster-based permutation approach, as well as accuracy-judgement responses during test. Results revealed for musicians a late positive component in the ERP during testing, but neither an N400 (400-800 ms) nor behavioral effects were found at test, while athletes did not show any effect of learning. Moreover, the object-label-ordering group only exhibited emerging association effects during training, while the label-object-ordering group showed a trend-level late ERP effect (800-1200 ms) during test as well as above chance accuracy-judgement scores. Thus, our results suggest the learner-related property of auditory expertise and stimulus-related manipulation of stimulus ordering modulate auditory associative word learning in adults.

Prolonged COVID-19 related effects on early language development: A longitudinal study.

BACKGROUND: There is growing evidence that COVID-19 brought changes that immediately affected early language development. Little is known for how long these COVID-19 related changes shaped development. The current study systematically and longitudinally addressed this issue, following up children's language development throughout the first 2.5 years. METHOD: The present study follows up on the sample from Frota et al. (2022), which demonstrated that 7-9-month-old infants born and raised during the pandemic do not segment words unlike pre-pandemic peers. Four studies were conducted: (1) word segmentation task at 12 months of age (Npandemic = 15); (2) word learning task at 20 months of age (Npandemic = 20); (3) language and communication development up to 30 months of age, via CDI and CSBS parental reports (Npandemic ranged 25-74); (4) overall development at 30 months of age using the Griffiths Developmental Scales (Npandemic = 16). RESULTS: The pandemic sample consistently underperformed in all four studies in comparison to pre-pandemic data. There was no evidence of developed word segmentation abilities at 12 months of age, and no successful word learning at 20 months of age. Lexical development between 12 and 24 months of age was lower than in the pre-pandemic sample, while social communication did not seem to be affected. At 30 months of age, the pandemic sample showed lower scores and lower mental age on the Language and Communication Griffiths' subscale, in comparison to the pre-pandemic data. CONCLUSIONS: Infants born and raised during the pandemic have a poorer language development, that persists at least until 30 months of age.

Are brain activity changes underlying rare word production after learning specific or do they extend to semantically related rare words?

Learning words in the mother tongue is a fundamental lifelong skill that involves complex cognitive and neural changes. In adults, newly learned words affect the organization of the lexical-semantic network and, compared to words that have been in the lexicon for longer, they activate the same cortical areas, but more extensively and/or intensively. It is however still unclear (1) which brain and cognitive processes underlying word production change when infrequent/unknown words are compared before and after learning and (2) whether integrating newly learned words impacts word specific processes or has a broader impact on unlearned words. The present study aims to investigate the electrophysiological changes underlying the production of rare words induced by learning and the effect of learning on an unlearned list of rare words belonging to the same semantic categories. To this end, 24 neurotypical adults learned one of two matched lists of 40 concrete rare words from 4 semantic categories. EEG (electroencephalographic) recordings were acquired during a referential word production task (picture naming) of the learned and unlearned words before and after the learning phase. The results show that the production of rare word is associated with event-related (ERP) differences between before and after learning in the period from 300 to 800 msec following the presentation of the imaged concept (picture). These differences consisted in a larger involvement of left temporal and parietal regions after learning between 300 and 400 msec i.e., the time window likely corresponding to lexical and phonological encoding processes. Crucially, the ERP changes are not restricted to the production of the learned rare words, but are also observed when participants try to retrieve words of a list of semantically and lexically matched rare words that they have not learned. The ERP changes on unlearned rare words are weaker and suggest that learning new words induces boarder effects also on unlearned words.

Word learning is hands-on: Insights from studying natural behavior.

Infants' interactions with social partners are richly multimodal. Dyads respond to and coordinate their visual attention, gestures, vocalizations, speech, manual actions, and manipulations of objects. Although infants are typically described as active learners, previous experimental research has often focused on how infants learn from stimuli that is well-crafted by researchers. Recent research studying naturalistic, free-flowing interactions has explored the meaningful patterns in dyadic behavior that relate to language learning. Infants' manual engagement and exploration of objects supports their visual attention, creates salient and diverse views of objects, and elicits labeling utterances from parents. In this chapter, we discuss how the cascade of behaviors created by infant multimodal attention plays a fundamental role in shaping their learning environment, supporting real-time word learning and predicting later vocabulary size. We draw from recent at-home and cross-cultural research to test the validity of our mechanistic pathway and discuss why hands matter so much for learning. Our goal is to convey the critical need for developmental scientists to study natural behavior and move beyond our "tried-and-true" paradigms, like screen-based tasks. By studying natural behavior, the role of infants' hands in early language learning was revealed-though it was a behavior that was often uncoded, undiscussed, or not even allowed in decades of previous research. When we study infants in their natural environment, they can show us how they learn about and explore their world. Word learning is hands-on.

Consolidation improves the learning of new meanings for known words but not necessarily their integration into semantic memory.

Consolidation is essential to the integration of novel words into the mental lexicon; however, its role in learning new meanings for known words remains unclear. This old-form-new-meaning learning is very common, as when one learns that "skate" is also a type of fish in addition to its familiar roller- or ice-skating meaning. To address consolidation effects for new meanings, we compared the behavioral and ERP measures on new and original meanings tested 24 hours after learning with words tested immediately after learning. Semantic judgments of both new and original meanings benefitted from the study-test interval. However, N400 amplitudes on studied words-indicators of meaning access from semantic memory-were unaffected by learning or consolidation. These results suggest that while sleep benefits memory for new meanings, the new meanings do not become integrated into the mental lexicon within that period. Instead, episodic retrieval remains functional in accessing new meanings even after 24 hours.

Co-learning companionship benefits word learning in a new language: Evidence from a dual-brain EEG examination.

Companionship refers to one's being in the presence of another individual. For adults, acquiring a new language is a highly social activity that often involves learning in the context of companionship. However, the effects of companionship on new language learning have gone relatively underexplored, particularly with respect to word learning. Using a within-subject design, the current study employs electroencephalography to examine how two types of companionship (monitored and co-learning) affect word learning (semantic and lexical) in a new language. Dyads of Chinese speakers of English as a second language participated in a pseudo-word-learning task during which they were placed in monitored and co-learning companionship contexts. The results showed that exposure to co-learning companionship affected the early attention stage of word learning. Moreover, in this early stage, evidence of a higher representation similarity between co-learners showed additional support that co-learning companionship influenced attention. Observed increases in delta and theta interbrain synchronization further revealed that co-learning companionship facilitated semantic access. In all, the similar neural representations and interbrain synchronization between co-learners suggest that co-learning companionship offers important benefits for learning words in a new language.

Objectifying subjective memory complaints: VR-based Verbal Word Learning Test in chronic stroke patients.

Memory impairment imposes a great burden on stroke patients and can be divided into Objective Memory Problems (OMPs) and Subjective Memory Complaints (SMCs). Studies have shown that these do not always co-occur. Possibly, the gap between SMCs and OMPs can be bridged when using a more ecologically valid memory test and considering the impact of other common stroke symptoms such as sensory hypersensitivity (SHS) and fatigue. In the present study, we applied Virtual Reality (VR) to create a sensory-rich environment with real-life stimuli. Memory performance was tested with the 15-Verbal Word Learning Test (VLT). Furthermore, we assessed SMCs (Everyday Memory Questionnaire), and the levels of SHS (Multi-Modal Evaluation of Sensory Sensitivity) and fatigue in the previous month. 31 chronic stroke patients and 32 healthy controls participated. The results showed that participants' memory performance decreased in a sensory-rich compared to a neutral environment. This decrease did not significantly differ between the groups. Interestingly, fatigue and SHS are related to the level of SMC in stroke patients but no such evidence was found in healthy controls. Last, for stroke patients, we found a significant negative correlation between SMCs and memory performance in a sensory-rich environment, but not in a neutral environment. In conclusion, our study implicates that in stroke patients, fatigue and SHS are related to SMCs and that using a sensory-rich VR environment might be a more ecologically valid way to objectify SMCs. However, interpretative caution is warranted due to the absence of sex and age-matched controls and potential selection bias.

Linking acoustic variability in the infants' input to their early word production.

Exposure to talker variability shapes how learning unfolds in the lab, and occurs in the everyday speech infants hear in daily life. Here, we asked whether aspects of talker variability in speech input are also linked to the onset of word production. We further asked whether these effects were redundant with effects of speech register (i.e., whether speech input was adult- vs. child-directed). To do so, we first extracted a set of highly common nouns from a longitudinal corpus of home recordings from North-American English-learning infants. We then used the acoustic variability in how these tokens were said to predict when the children first produced these same nouns. We found that in addition to frequency, variability in how words sound in 6-17 month's input predicted when children first said these words. Furthermore, while the proportion of child-directed speech also predicted the month of first production, it did so alongside measurements of acoustic variability in children's real-world input. Together, these results add to a growing body of literature suggesting that variability in how words sound in the input is linked to learning both in the lab and in daily life. RESEARCH HIGHLIGHTS: Talker variability shapes learning in the lab and exists in everyday speech; we asked whether it predicts word learning in the real world. Acoustic measurements of early words in infants' input (and their frequency) predicted when infants first said those same words. Speech register also predicted when infants said words, alongside effects of talker variability. Our results provide a deeper understanding of how sources of variability inherent to children's input connect to their learning and development.

A Continuity in Logical Development: Domain-General Disjunctive Inference by Toddlers.

Children grow up surrounded by opportunities to learn (the language of their community, the movements of their body, other people's preferences and mental lives, games, social norms, etc.). Here, we find that toddlers (N = 36; age range 2.3-3.2 years) rely on a logical reasoning strategy, Disjunctive Inference (i.e., A OR B, A is ruled out, THEREFORE, B), across a variety of situations, all before they have any formal education or extensive experience with words for expressing logical meanings. In learning new words, learning new facts about a person, and finding the winner of a race, toddlers systematically consider and reject competitors before deciding who must be the winner. This suggests that toddlers may have a general-purpose logical reasoning tool that they can use in any situation.

Establishing neural representations for new word forms in 12-month-old infants.

During the first year of life, infants start to learn the lexicon of their native language. Word learning includes the establishment of longer-term representations for the phonological form and the meaning of the word in the brain, as well as the link between them. However, it is not known how the brain processes word forms immediately after they have been learned. We familiarized 12-month-old infants (N = 52) with two pseudowords and studied their neural signatures. Specifically, we determined whether a newly learned word form elicits neural signatures similar to those observed when a known word is recognized (i.e., when a well-established word representation is activated, eliciting enhanced mismatch responses) or whether the processing of a newly learned word form shows the suppression of the neural response along with the principles of predictive coding of a learned rule (i.e., the order of the syllables of the new word form). The pattern of results obtained in the current study suggests that recognized word forms elicit a mismatch response of negative polarity, similar to newly learned and previously known words with an established representation in long-term memory. In contrast, prediction errors caused by acoustic novelty or deviation from the expected order in a sequence of (pseudo)words elicit responses of positive polarity. This suggests that electric brain activity is not fully explained by the predictive coding framework.

The role of frontal cortex in novel-word learning and consolidation: Evidence from focal transcranial direct current stimulation.

Previous studies have demonstrated that conventional transcranial direct current stimulation (tDCS) can enhance novel-word learning. However, because of the widespread current that is induced by these setups and lack of appropriate control conditions, little is known about the underlying neural mechanisms. In the present double-blinded and sham-tDCS controlled study, we investigated for the first time if regionally precise focal tDCS targeting two key nodes of the novel-word learning network at different time points would result in regionally and temporally distinct effects. 156 participants completed a contextual novel-word-learning paradigm and learning success was probed immediately after the acquisition period and 30-min later. Participants were randomly assigned to six stimulation conditions: Active tDCS (1.5 mA) was administered to left inferior frontal (IFG) or middle temporal gyrus (MTG), either during acquisition or delayed recall. Control groups received sham-tDCS either during acquisition or delayed recall (50% IFG/MTG). Data were analyzed with a generalized linear mixed model with a binomial link function in a Bayesian framework. Our results showed that frontal tDCS selectively increased accuracy gains from immediate to delayed recall, irrespective of timing of the stimulation. There was no evidence for beneficial effects of middle temporal gyrus tDCS. Our findings confirm that IFG tDCS can enhance novel-word learning in a regionally, but not timing specific way. Tentatively, this may be explained by enhancement of semantic selection processes resulting in more effective consolidation and/or retrieval. Future studies using longer time intervals between assessments are required to clarify the potential contribution of neurophysiological after-effects of IFG tDCS administered during acquisition to enhanced consolidation.

Contribution of orthography to vocabulary acquisition in a second language: Evidence of an early word-learning advantage in elementary-school children.

Recent studies have shown that children benefit from orthography when learning new words. This orthographic facilitation can be explained by the fact that written language acts as an anchor device due to the transient nature of spoken language. There is also a close and reciprocal relationship between spoken and written language. Second-language word learning poses specific challenges in terms of orthography-phonology mappings that do not fully overlap with first-language mappings. The current study aimed to investigate whether orthographic information facilitates second-language word learning in developing readers, namely third and fifth graders. In a first experiment French children learned 16 German words, and in a second experiment they learned 24 German words. Word learning was assessed by picture designation, spoken word recognition, and orthographic choice. In both experiments, orthographic facilitation was found in both less and more advanced readers. The theoretical and practical implications of these findings are discussed.

Constraints on novel word learning in heritage speakers.

Introduction: Recent research on word learning has found that adults can rapidly learn novel words by tracking cross-situational statistics, but learning is greatly influenced by the phonological properties of the words and by the native language of the speakers. Mandarin-native speakers could easily pick up novel words with Mandarin tones after a short exposure, but English-native speakers had specific difficulty with the tonal components. It is, however, unclear how much experience with Mandarin is needed to successfully use the tonal cue in word learning. In this study, we explored this question by focusing on the heritage language population, who typically are exposed to the target language at an early age but then develop and switch to another majority language. Specifically, we investigated whether heritage Mandarin speakers residing in an English-speaking region and speaking English as a dominant language would be able to learn novel Mandarin tonal words from statistical tracking. It helps us understand whether early exposure to the target feature is sufficient to promote the use of that feature in word learning later in life. Methods: We trained 30 heritage Mandarin speakers with Mandarin pseudowords via a cross-situational statistical word learning task (CSWL). Results and discussion: Heritage Mandarin speakers were able to learn the pseudowords across multiple situations, but similar-sounding words (i.e., minimal pairs) were more difficult to identify, and words that contrast only in lexical tones (i.e., Mandarin lexical tone) were distinguished at chance level throughout learning. We also collected information about the participants' heritage language (HL) experience and usage. We did not observe a relationship between HL experience/usage and performance in tonal word learning, suggesting that HL exposure does not necessarily lead to an advantage in learning the target language.

The role of handwriting in English word acquisition among elementary students.

In order to investigate whether handwriting has an advantage in learning word form, sound, and meaning, this study randomly selected 40 elementary school student participants (20 males, 20 females, aged 11.4 ± 1.34 years). Using an experimental approach, we compared the learning outcomes of word sound matching, word meaning matching, and word form judgment tasks under two conditions: handwriting and visual learning. After three consecutive days of learning and testing, we found that handwriting generally outperformed visual learning in terms of accuracy and response time in word form, sound, and meaning learning. Additionally, we observed differences in the timing of significant discrepancies in learning outcomes between the two methods across the three tasks. Specifically, in terms of accuracy, discrepancies first appeared in the word sound matching task on the first day, followed by the word form judgment task, and lastly the word meaning matching task. Regarding response time, significant differences between learning methods first emerged in the word form judgment task, followed by the word sound and word meaning tasks. Thus, combining accuracy and response time data, we conclude that handwriting is more advantageous than visual learning for word acquisition, with a differential impact on word form, sound, and meaning, where word form and sound are prioritized over meaning.

Navigating accent variability: 24-month-olds recognize known words spoken in an unfamiliar accent but require additional support to learn new words.

As infants learn their native languages, they must also learn to contend with variability across speakers of those languages. Here, we examine 24-month-olds' ability to process speech in an unfamiliar accent. We demonstrate that 24-month-olds successfully identify the referents of known words in unfamiliar-accented speech but cannot use known words alone to infer new word meanings. However, when the novel word occurs in a supportive referential context, with the target referent visually available, 24-month-olds successfully learn new word-referent mappings. Thus, 24-month-olds recognize and learn words in unfamiliar accents, but unfamiliar-accented speech may pose challenges for more sophisticated language processing strategies.

Infants who are rarely spoken to nevertheless understand many words.

Theories of language development-informed largely by studies of Western, middleclass infants-have highlighted the language that caregivers direct to children as a key driver of language learning. However, some have argued that language development unfolds similarly across environmental contexts, including those in which childdirected language is scarce. This raises the possibility that children are able to learn from other sources of language in their environments, particularly the language directed to others in their environment. We explore this hypothesis with infants in an indigenous Tseltal-speaking community in Southern Mexico who are rarely spoken to, yet have the opportunity to overhear a great deal of other-directed language by virtue of being carried on their mothers' backs. Adapting a previously established gaze-tracking method for detecting early word knowledge to our field setting, we find that Tseltal infants exhibit implicit knowledge of common nouns (Exp. 1), analogous to their US peers who are frequently spoken to. Moreover, they exhibit comprehension of Tseltal honorific terms that are exclusively used to greet adults in the community (Exp. 2), representing language that could only have been learned through overhearing. In so doing, Tseltal infants demonstrate an ability to discriminate words with similar meanings and perceptually similar referents at an earlier age than has been shown among Western children. Together, these results suggest that for some infants, learning from overhearing may be an important path toward developing language.