Vois‐Tu Le Kem? Do You See the Bos? Foreign Word Learning at 14 Months

How easily can infants regularly exposed to only one language begin to acquire a second one? In three experiments, we tested 14‐month‐old English and French monolingual infants’ ability to learn words presented in foreign language sentence frames. Infants were trained on two novel word‐object pairings and then tested using a preferential looking task. Word forms were phonetically and phonotactically legal in both languages, and cross‐spliced across conditions, so only the sentence frames established the word as native or foreign. In Experiment 1, infants were taught one native and one foreign word and successfully learned both. In Experiment 2 and 3, infants were taught two foreign words, but only showed successful learning of the first word they encountered. These results demonstrate that infants can successfully learn words embedded in foreign language sentences, but this is more challenging than native word learning. More broadly, they show that the sentential context of a novel word, and not just the word form itself, influences infants’ early word learning.     

Beneficial effects of the mother's voice on infants’ novel word learning

The maternal voice appears to have a special role in infants’ language processing. The current eye‐tracking study investigated whether 24‐month‐olds (n = 149) learn novel words easier while listening to their mother's voice compared to hearing unfamiliar speakers. Our results show that maternal speech facilitates the formation of new word–object mappings across two different learning settings: a live setting in which infants are taught by their own mother or the experimenter, and a prerecorded setting in which infants hear the voice of either their own or another mother through loudspeakers. Furthermore, this study explored whether infants’ pointing gestures and novel word productions over the course of the word learning task serve as meaningful indexes of word learning behavior. Infants who repeated more target words also showed a larger learning effect in their looking behavior. Thus, maternal speech and infants’ willingness to repeat novel words are positively linked with novel word learning.     

Word Segmentation in Monolingual Infants Acquiring Canadian English and Canadian French: Native Language,Cross‐Dialect,and Cross‐Language Comparisons

In five experiments, we tested segmentation of word forms from natural speech materials by 8‐month‐old monolingual infants who are acquiring Canadian French or Canadian English. These two languages belong to different rhythm classes; Canadian French is syllable‐timed and Canada English is stress‐timed. Findings of Experiments 1, 2, and 3 show that 8‐month‐olds acquiring either Canadian French or Canadian English can segment bi‐syllable words in their native language. Thus, word segmentation is not inherently more difficult in a syllable‐timed compared to a stress‐timed language. Experiment 4 shows that Canadian French‐learning infants can segment words in European French. Experiment 5 shows that neither Canadian French‐ nor Canadian English‐learning infants can segment two syllable words in the other language. Thus, segmentation abilities of 8‐month‐olds acquiring either a stress‐timed or syllable‐timed language are language specific.     

Object Familiarity Enhances Infants’ Use of Phonetic Detail in Novel Words

Infants greatly refine their ability to discriminate language sounds by 12 months, yet 14‐month‐olds appear to confuse similar‐sounding novel words. Two explanations could account for this phenomenon: infants initially have incomplete phoneme representations, suggesting developmental discontinuity; or word‐learning demands interfere with use of established phonetic detail. These hypotheses were tested at 14 months by pairing a novel word with an object preexposed to half the infants and novel to the other half. If demands are key, only preexposed infants should efficiently use phonetic detail; there is no need to concurrently learn object details with the word. If representations lack detail, object familiarity should not matter. Only infants preexposed to the object noticed a change in its label, thus challenging the discontinuity position and demonstrating the impact of object familiarity on early word learning.     

Phonotactic Constraints on Infant Word Learning

How do infants use their knowledge of native language sound patterns when learning words? There is ample evidence of infants’ precocious acquisition of native language sound structure during the first year of life, but much less evidence concerning how they apply this knowledge to the task of associating sounds with meanings in word learning. To address this question, 18‐month‐olds were presented with two phonotactically legal object labels (containing sound sequences that occur frequently in English) or two phonotactically illegal object labels (containing sound sequences that never occur in English), paired with novel objects. Infants were then tested using a looking‐while‐listening measure. The results revealed that infants looked at the correct objects after hearing the legal labels, but not the illegal labels. Furthermore, vocabulary size was related to performance. Infants with larger receptive vocabularies displayed greater differences between learning of legal and illegal labels than infants with smaller vocabularies. These findings provide evidence that infants’ knowledge of native language sound patterns influences their word learning.     

The Use of Pitch Accent in Word–Object Association by Monolingual Japanese Infants

This study investigated the lexical use of Japanese pitch accent in Japanese‐learning infants. A word–object association task revealed that 18‐month‐old infants succeeded in learning the associations between two nonsense objects paired with two nonsense words minimally distinguished by pitch pattern (Experiment 1). In contrast, 14‐month‐old infants failed (Experiment 2). Eighteen‐month‐old infants succeeded even for sounds that contained only the prosodic information (Experiment 3). However, a subsequent experiment revealed that 14‐month‐old infants succeeded in an easier single word–object task using pitch contrast (Experiment 4). These findings indicate that pitch pattern information is robustly available to 18‐month‐old Japanese monolingual infants in a minimal pair word‐learning situation, but only partially accessible in the same context for 14‐month‐old infants.     

The Organization of Words and Symbolic Gestures in 18‐Month‐Olds’ Lexicons: Evidence From a Disambiguation Task

Infants’ early communicative repertoires include both words and symbolic gestures. The current study examined the extent to which infants organize words and gestures in a single unified lexicon. As a window into lexical organization, eighteen‐month‐olds’ (N = 32) avoidance of word–gesture overlap was examined and compared with avoidance of word–word overlap. The current study revealed that when presented with novel words, infants avoided lexical overlap, mapping novel words onto novel objects. In contrast, when presented with novel gestures, infants sought overlap, mapping novel gestures onto familiar objects. The results suggest that infants do not treat words and gestures as equivalent lexical items and that during a period of development when word and symbolic gesture processing share many similarities, important differences also exist between these two symbolic forms.     

Long‐Term Memory for an Emotional Interpersonal Interaction Occurring at 5 Months of Age

We examined infants' long‐term retention of a single unique emotional experience into early childhood. Twenty‐month‐olds who had participated in a still‐face procedure at 5 months (experience group) fixated the face of the person who had instigated the still face significantly less than the faces of 2 other novel persons. Control 20‐month‐olds (no‐experience group) looked longer overall and fixated the target person equally or more than the 2 novel persons. In short, children who interacted with a stranger in the laboratory under both natural and anomalous social conditions just once when they were infants apparently retained a specific memory of that person and the experience into toddlerhood.     

Word Level Stress and Lexical Processing in 17‐Month‐Old Infants

Detailed representations enable infants to distinguish words from one another and more easily recognize new words. We examined whether 17‐month‐old infants encode word stress in their familiar word representations. In Experiment 1, infants were presented with pairs of familiar objects while hearing a target label either properly pronounced with the correct stress (e.g., baby /’be?bi/) or mis‐pronounced with the incorrect stress pattern (e.g., baby /be?’bi/). Infants mapped both the correctly stressed and mis‐stressed labels to the target objects; however, they were slower to fixate the target when hearing the mis‐stressed label. In Experiment 2, we examined whether infants appreciate that stress has a nonproductive role in English (i.e., altering the stress of a word does not typically signal a change in word meaning) by presenting infants with a familiar object paired with a novel object while hearing either correctly stressed or mis‐stressed familiar words (Experiment 2). Here, infants mapped the correctly stressed label to the familiar object but did not map the mis‐stressed label reliably to either the target or distractor objects. These findings suggest that word stress impacts the processing of familiar words, and infants have burgeoning knowledge that altering the stress pattern of a familiar word does not reliably signal a new referent.     

Nineteen‐Month‐Olds' Understanding of the Conventionality of Object Labels Versus Desires

We assessed 19‐month‐olds' appreciation of the conventional nature of object labels versus desires. Infants played a finding game with an experimenter who stated her intention to find the referent of a novel word (word group), to find an object she wanted (desire group), or simply to look in a box (control group). A 2nd experimenter then administered a comprehension task to assess infants' tendency to extend information to a 2nd person who was not present at the time of learning. Results indicate that infants chose the target object when the 2nd experimenter asked for the referent of the novel label but not when she requested the referent of her desire. These findings demonstrate that 19‐month‐olds understand that words are conventional, but desires are not.     

Monolingual and bilingual infants’ word segmentation abilities in an inter‐mixed dual‐language task

Previous studies show that young monolingual infants use language‐specific cues to segment words in their native language. Here, we asked whether 8 and 10‐month‐old infants (N = 84) have the capacity to segment words in an inter‐mixed bilingual context. Infants heard an English‐French mixed passage that contained one target word in each language, and were then tested on their recognition of the two target words. The English‐monolingual and French‐monolingual infants showed evidence of segmentation in their native language, but not in the other unfamiliar language. As a group, the English‐French bilingual infants segmented in both of their native languages. However, exploratory analyses suggest that exposure to language mixing may play a role in bilingual infants’ segmentation skills. Taken together, these results indicate a close relation between language experience and word segmentation skills.     

Infants' First Words are not Phonetically Specified: Own Name Recognition in British English‐Learning 5‐Month‐Olds

By the end of their first year of life, infants’ representations of familiar words contain phonetic detail; yet little is known about the nature of these representations at the very beginning of word learning. Bouchon et al. ( 2015 ) showed that French‐learning 5‐month‐olds could detect a vowel change in their own name and not a consonant change, but also that infants reacted to the acoustic distance between vowels. Here, we tested British English‐learning 5‐month‐olds in a similar study to examine whether the acoustic/phonological characteristics of the native language shape the nature of the acoustic/phonetic cues that infants pay attention to. In the first experiment, British English‐learning infants failed to recognize their own name compared to a mispronunciation of initial consonant (e.g., Molly versus Nolly) or vowel (e.g., April versus Ipril). Yet in the second experiment, they did so when the contrasted name was phonetically dissimilar (e.g., Sophie versus Amber). Differences in phoneme category (stops versus continuants) between the correct consonant versus the incorrect one significantly predicted infants’ own name recognition in the first experiment. Altogether, these data suggest that infants might enter into a phonetic mode of processing through different paths depending on the acoustic characteristics of their native language.     

14‐Month‐olds anticipate others’ actions based on their belief about an object's identity

Past research has accumulated evidence regarding infants’ false‐belief understanding, measuring their gaze patterns or active helping behaviors. However, the underlying mechanisms are still debated, specifically, whether young infants can compute that others represent the world under a certain aspect. Such performance requires holding in mind two representations about the same object simultaneously and attributing only one to another person. While 14‐month‐olds can encode an object under different aspects when forming first‐person representations, it is unclear whether infants at this very age could also predict others’ behavior based on their beliefs about an object's identity. Here, we investigate this question in a novel eye‐tracking‐based unexpected‐identity task. We measured 14‐month‐olds’ anticipatory looks combined with their looking time, using a violation‐of‐expectation paradigm. Results show that 14‐month‐olds look longer to an actor's reach that is incongruent with her false belief about the identity of an object compared to a congruent reach. Furthermore, infants correctly anticipated the actor's reach based on her false belief. Thus, as soon as infants represent dual identities they can integrate them in belief attributions and use them for consequent behavioral predictions. Such data provide evidence for the flexibility of false‐belief attributions and support proposals arguing for infants’ rich theory‐of‐mind abilities.     

Infant Perception of Surface Texture and Relative Height as Distance Information: A Preferential‐Reaching Study

Two preferential‐reaching experiments explored 5‐ and 7‐month‐olds’ sensitivity to pictorial depth cues. In the first experiment, infants viewed a display in which texture gradients, linear perspective of the surface contours, and relative height in the visual field provided information that two objects were at different distances. Five‐ and 7‐month‐old infants reached preferentially for the apparently nearer object under monocular but not binocular viewing conditions, indicating that infants in both age groups respond to pictorial depth cues. In the second experiment, texture gradients and linear perspective of the surface contours were eliminated from the experimental display, making relative height the sole pictorial depth cue. Seven‐month‐olds again reached more often for the apparently nearer object under monocular, but not binocular viewing conditions. By contrast, the 5‐month‐olds’ reaching behavior did not differ between viewing conditions. These results indicate that 7‐month‐olds respond to the depth cue of relative height but provide no evidence of responsiveness to relative height in 5‐month‐olds. Both age groups responded more consistently to pictorial depth in Experiment 1 than in Experiment 2.     

Learning While Babbling: Prelinguistic Object‐Directed Vocalizations Indicate a Readiness to Learn

Two studies illustrate the functional significance of a new category of prelinguistic vocalizing—object‐directed vocalizations (ODVs)—and show that these sounds are connected to learning about words and objects. Experiment 1 tested 12‐month‐old infants’ perceptual learning of objects that elicited ODVs. Fourteen infants’ vocalizations were recorded as they explored novel objects. Infants learned visual features of objects that elicited the most ODVs but not of objects that elicited the fewest vocalizations. Experiment 2 assessed the role of ODVs in learning word–object associations. Forty infants aged 11.5 months played with a novel object and received a label either contingently on an ODV or on a look alone. Only infants who received labels in response to an ODV learned the association. Taken together, the findings suggest that infants’ ODVs signal a state of attention that facilitates learning.     

A Cross‐Linguistic Study of Word‐Mapping in 18‐ to 20‐Month‐Old Infants

This study was designed to examine whether infants acquiring languages that place a differential emphasis on nouns and verbs, focus their attention on motions or objects in the presence of a novel word. An infant‐controlled habituation paradigm was used to teach 18‐ to 20‐month‐old English‐, French‐, and Japanese‐speaking infants’ novel words for events. Infants were habituated to two word‐event pairings and then presented with new combinations that involved a familiar word with a new object or motion, or both. Children could map the novel word to both the object and the motion, despite the differential salience of object and motion words in their native language. A control experiment with no label confirmed that both object and motion changes were detectable.     

Learning Words Over Time: The Role of Stimulus Repetition in Mutual Exclusivity

During the second year of life, infants develop a preference to attach novel labels to novel objects. This behavior is commonly known as “mutual exclusivity” (Markman, 1989). In an intermodal preferential looking experiment with 19.5‐ and 22.5‐month‐olds, stimulus repetition was critical for observing mutual exclusivity. On the first occasion that a novel label was presented with 1 familiar object and 1 novel object, looking behavior was unsystematic. However, on reexposure to the same stimuli, 22.5‐month‐olds looked preferentially at the novel object prior to the re‐presentation of the novel label. These findings suggest a powerful memory mechanism for novel labels and objects, enabling mutual exclusivity to emerge across repeated exposures to potential referents.     

Better Processing of Consonantal Over Vocalic Information in Word Learning at 16 Months of Age

Previous research using the name‐based categorization task has shown that 20‐month‐old infants can simultaneously learn 2 words that only differ by 1 consonantal feature but fail to do so when the words only differ by 1 vocalic feature. This asymmetry was taken as evidence for the proposal that consonants are more important than vowels at the lexical level. This study explores this consonant‐vowel asymmetry in 16‐month‐old infants, using an interactive word learning task. It shows that the pattern of the 16‐month‐olds is the same as that of the 20‐month‐olds. Infants succeeded with 1‐feature consonantal contrasts (either place or voicing) but were at chance level with 1‐feature vocalic contrasts (either place or height). These results thus contribute to a growing body of evidence establishing, from early infancy to adulthood, that consonants and vowels have different roles in lexical acquisition and processing.     

Functional Elements in Infants' Speech Processing: The Role of Determiners in the Syntactic Categorization of Lexical Elements

How do children determine the syntactic category of novel words? In this article we present the results of 2 experiments that investigated whether German children between 12 and 16 months of age can use distributional knowledge that determiners precede nouns and subject pronouns precede verbs to syntactically categorize adjacent novel words. Evidence from the head‐turn preference paradigm shows that, although 12‐ to 13‐month‐olds cannot do this, 14‐ to 16‐month‐olds are able to use a determiner to categorize a following novel word as a noun. In contrast, no categorization effect was found for a novel word following a subject pronoun. To understand this difference we analyzed adult child‐directed speech. This analysis showed that there are in fact stronger co‐occurrence relations between determiners and nouns than between subject pronouns and verbs. Thus, in German determiners may be more reliable cues to the syntactic category of an adjacent novel word than are subject pronouns. We propose that the capacity to syntactically categorize novel words, demonstrated here for the first time in children this young, mediates between the recognition of the specific morphosyntactic frame in which a novel word appears and the word‐to‐world mapping that is needed to build up a semantic representation for the novel word.     

Sensitivity to Confidence Cues Increases during the Second Year of Life

We investigated the emergence in infancy of a preference to imitate individuals who display confidence over lack of confidence. Eighteen‐ and 24‐month‐olds (N = 70) were presented with an experimenter who demonstrated the use of several objects accompanied by either nonverbal expressions of confidence or lack of confidence. At 24 months, infants were more likely to imitate the actions when demonstrated by a confident experimenter than by an unconfident experimenter; 18‐month‐olds showed no such preference. The experimenter then presented an additional imitation trial and a word‐learning trial while displaying a neutral expression. Twenty‐four‐month‐olds persisted in preferentially imitating a previously confident experimenter, but prior confidence had no effect on their word learning. These findings demonstrate a developmental increase in infants’ use of confidence cues toward the end of the second year of life.