Syntactic Categorization in French‐Learning Infants

Recent work showed that infants recognize and store function words starting from the age of 6–8 months. Using a visual fixation procedure, the present study tested whether French‐learning 14‐month‐olds have the knowledge of syntactic categories of determiners and pronouns, respectively, and whether they can use these function words for categorizing novel words to nouns and verbs. The prosodic characteristics of novel words stimuli for noun versus verb uses were balanced. The only distinguishing cue was the preceding determiners versus subject pronouns, the former being the most common for nouns and the latter the most common for verbs, i.e., Det + Noun, Pron + Verb. We expected that noun categorization may be easier than verb categorization because the co‐occurrence of determiners with nouns is more consistent than that of subject pronouns with verbs in French. The results showed that infants grouped the individual determiners as one common class, and that they appeared to use the determiners to categorize novel words into nouns. However, we found no evidence of verb categorization. Unlike determiners, pronouns were not perceived as a common syntactic class.     

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.     

Receptive Grammatical Knowledge of Familiar Content Words and Inflection in 16‐Month‐Olds

This study examines 16‐month‐olds' understanding of word order and inflectional properties of familiar nouns and verbs. Infants preferred grammatical sentences over ungrammatical sentences when the ungrammaticality was cued by both misplaced inflection and word order reversal of nouns and verbs. Infants were also sensitive to inflection alone as a cue to grammaticality, but not word order alone. The preference for grammatical sentence forms was also disrupted when adjacent function word cues were removed from the stimuli, and when familiar content words were replaced by nonce words. These results suggest that sensitivity to the relationship between functional morphemes and content words, rather than sensitivity to either independently, drives the development of early grammatical knowledge. Furthermore, infants showed some ability to generalize from familiar to nonce content word contexts.     

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.     

Successful Word Recognition by 10‐Month‐Olds Given Continuous Speech Both at Initial Exposure and Test

Most words that infants hear occur within fluent speech. To compile a vocabulary, infants therefore need to segment words from speech contexts. This study is the first to investigate whether infants (here: 10‐month‐olds) can recognize words when both initial exposure and test presentation are in continuous speech. Electrophysiological evidence attests that this indeed occurs: An increased extended negativity (word recognition effect) appears for familiarized target words relative to control words. This response proved constant at the individual level: Only infants who showed this negativity at test had shown such a response, within six repetitions after first occurrence, during familiarization.     

Can 18‐Month‐Old Infants Learn Words by Listening In on Conversations?

Previous research has shown that children as young as 2 can learn words from 3rd‐party conversations (Akhtar, Jipson, & Callanan, 2001). The focus of this study was to determine whether younger infants could learn a new word through overhearing. Novel object labels were introduced to 18‐month‐old infants in 1 of 2 conditions: directly by an experimenter or in the context of overhearing the experimenter use the word while interacting with another adult. The findings suggest that, when memory demands are not too high, 18‐month‐old infants can learn words through overhearing.     

Phonological Specificity in 12‐ and 17‐Month‐Old French‐Speaking Infants

The literature reports some contradictory results on the degree of phonological specificity of infants’ early lexical representations in the Romance language, French, and Germanic languages. It is not clear whether these discrepancies are because of differences in method, in language characteristics, or in participants’ age. In this study, we examined whether 12‐ and 17‐month‐old French‐speaking infants are able to distinguish well‐pronounced from mispronounced words (one or two features of their initial consonant). To this end, 46 infants participated in a preferential looking experiment in which they were presented with pairs of pictures together with a spoken word well pronounced or mispronounced. The results show that both 12‐ and 17‐month‐old infants look longer at the pictures corresponding to well‐pronounced words than to mispronounced words, but show no difference between the two mispronunciation types. These results suggest that, as early as 12 months, French‐speaking infants, like those exposed to Germanic languages, already possess detailed phonological representations of familiar words.     

From Syllables to Syntax: Multilevel Statistical Learning by 12‐Month‐Old Infants

To successfully acquire language, infants must be able to track multiple levels of regularities in the input. In many cases, regularities only emerge after some learning has already occurred. For example, the grammatical relationships between words are only evident once the words have been segmented from continuous speech. To ask whether infants can engage in this type of learning process, 12‐month‐old infants in 2 experiments were familiarized with multiword utterances synthesized as continuous speech. The words in the utterances were ordered based on a simple finite‐state grammar. Following exposure, infants were tested on novel grammatical and ungrammatical sentences. The results indicate that the infants were able to perform 2 statistical learning tasks in sequence: first segmenting the words from continuous speech, and subsequently discovering the permissible orderings of the words. Given a single set of input, infants were able to acquire multiple levels of structure, suggesting that multiple levels of representation (initially syllable‐level combinations, subsequently word‐level combinations) can emerge during the course of learning.     

Infant Recognition of Hebrew Vocalic Word Patterns

The ability of infants to recognize phonotactic patterns in their native language is widely acknowledged. However, the specific ability of infants to recognize patterns created by nonadjacent vowels in words has seldom been investigated. In Semitic languages such as Hebrew, groups of multisyllabic words are identical in their nonadjacent vowel sequences and stress position but differ in the consonants interposed between the vowels. The goals of this study were to assess whether infants learning Hebrew show a preference for (1) a nonadjacent vocalic pattern or template, common in Hebrew nouns (CéCeC), over a nonattested nonadjacent vocalic pattern (CóCoC), and (2) a nonadjacent vocalic pattern common in Hebrew words (CaCóC) over an existing but less common pattern (CaCéC). Twenty Hebrew‐learning infants aged 8 to 11 months were presented with lists of nonsense words featuring the first two patterns (Experiment 1), and 20 were presented with nonsense words featuring the second two patterns (Experiment 2). The results showed longer listening to CéCeC than to CóCoC lists and to CaCóC than to CaCéC lists, suggesting that infants recognized the common nonadjacent vocalic patterns in both cases. The study thus demonstrates that Hebrew‐learning infants are able to disregard the intervening consonants within words and generalize their vocalic pattern to previously unheard nonwords, whether this pattern includes identical or different vowels and regardless of the rhythmic pattern of the word (trochaic or iambic). Analysis of the occurrence of the relevant vowel patterns in input speech in three Hebrew corpora (two addressed to children and one to adults) suggests that exposure to these patterns in words underlies the infants' preferences.     

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.     

Twelve‐Month‐Olds Know Their Cups From Their Keps and Tups

Fourteen‐month‐olds are sensitive to mispronunciations of the vowels and consonants in familiar words (N. Mani & K. Plunkett (2007), Journal of Memory and Language, 57, 252; D. Swingley & R. N. Aslin (2002), Psychological Science, 13, 480). To examine the development of this sensitivity further, the current study tests 12‐month‐olds’ sensitivity to different kinds of vowel and consonant mispronunciations of familiar words. The results reveal that vocalic changes influence word recognition, irrespective of the kinds of vocalic changes made. While consonant changes influenced word recognition in a similar manner, this was restricted to place and manner of articulation changes. Infants did not display sensitivity to voicing changes. Infants’ sensitivity to vowel mispronunciations, but not consonant mispronunciations, was influenced by their vocabulary size—infants with larger vocabularies were more sensitive to vowel mispronunciations than infants with smaller vocabularies. The results are discussed in terms of different models attempting to chart the development of acoustically or phonologically specified representations of words during infancy.     

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.     

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.     

Twelve‐Month‐Olds Understand Social Intentions Based on Prosody and Gesture Shape

Infants infer social and pragmatic intentions underlying attention‐directing gestures, but the basis on which infants make these inferences is not well understood. Previous studies suggest that infants rely on information from preceding shared action contexts and joint perceptual scenes. Here, we tested whether 12‐month‐olds use information from act‐accompanying cues, in particular prosody and hand shape, to guide their pragmatic understanding. In Experiment 1, caregivers directed infants’ attention to an object to request it, share interest in it, or inform them about a hidden aspect. Caregivers used distinct prosodic and gestural patterns to express each pragmatic intention. Experiment 2 was identical except that experimenters provided identical lexical information across conditions and used three sets of trained prosodic and gestural patterns. In all conditions, the joint perceptual scenes and preceding shared action contexts were identical. In both experiments, infants reacted appropriately to the adults’ intentions by attending to the object mostly in the sharing interest condition, offering the object mostly in the imperative condition, and searching for the referent mostly in the informing condition. Infants’ ability to comprehend pragmatic intentions based on prosody and gesture shape expands infants’ communicative understanding from common activities to novel situations for which shared background knowledge is missing.     

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.     

Infant‐Directed Prosody Helps Infants Map Sounds to Meanings

Adults typically use an exaggerated, distinctive speaking style when addressing infants. However, the effects of infant‐directed (ID) speech on infants' learning are not yet well understood. This research investigates how ID speech affects how infants perform a key function in language acquisition, associating the sounds of words with their meanings. Seventeen‐month‐old infants were presented with two label‐object pairs in a habituation‐based word learning task. In Experiment 1, the labels were produced in adult‐directed (AD) speech. In Experiment 2, the labels were produced in ID prosody; they had higher pitch, greater pitch variation, and longer durations than the AD labels. We found that infants failed to learn the labels in AD speech, but succeeded in learning the same labels when they were produced in ID speech. Experiment 3 investigated the role of variability in learning from ID speech. When the labels were presented in ID prosody with no variation across tokens, infants failed to learn them. Our findings indicate that ID prosody can affect how readily infants map sounds to meanings and that the variability in prosody that is characteristic of ID speech may play a key role in its effect on learning new words.     

The Development of Gaze Following in a Third‐Party Context

Infants follow the gaze of an individual with whom they are directly interacting by the end of the first year. By 18 months infants are capable of learning novel words in observational (or third‐party) contexts (Floor & Akhtar, 2006). To examine third‐party gaze following in 12‐ and 18‐month‐olds, the parent and experimenter engaged in a conversation while the infant was present. For 8 trials approximately every 30 sec the experimenter would turn her head to the right or left to fixate on a toy placed on either side of the room with the parent following suit. In the first experiment, the parent was seated next to the infant and the experimenter opposite, whereas in the second experiment the positions of the adults were switched. In Experiment 1, 18‐month‐olds but not 12‐month‐olds followed gaze. In Experiment 2, 12‐month‐olds acquired a tendency to follow gaze during the experimental session. These results suggest that an incipient ability to follow third‐party gaze is present by 12 months and that infants acquire a more reliable and general ability to follow the gaze of noninteractive others between 12 and 18 months.     

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.     

Dynamic Noun Generalization: Moment‐to‐Moment Interactions Shape Children's Naming Biases

Recent research on early word learning suggests that children's behavior when‐generalizing novel nouns integrates their prior vocabulary knowledge with the specifics of the task. This study examines how these factors interact on the moment‐to‐moment time scale of the training children receive and the sequence of stimuli they are shown. In ***1 condition, we used a combination of training and stimulus factors predicted to produce a bias to generalize nouns by shape similarity. We then reduced this shape bias and amplified a bias to generalize nouns by material similarity via manipulations of training and stimuli across 3 other conditions. Additional analyses suggest that children's generalizations on individual trials are influenced by what they have seen and done on previous trials. These results highlight the importance of the task and stimuli in bringing children's prior knowledge to bear in early word learning.     

Cross‐Task Stability in Infant Attention: New Perspectives Using the Still‐Face Procedure

Infant visual attention has been studied extensively within cognitive paradigms using measures such as look duration and reaction time, but less work has examined how infant attention operates in social contexts. In addition, little is known about the stability of individual differences in attention across cognitive and social contexts. In this study, a cross‐sectional sample of 50 infants (4 and 6 months of age) were first tested in a look duration and reaction time task with static visual stimuli. Next, their mothers participated with the infants in the still‐face procedure, a mildly distressing social interaction paradigm that involves violation of expectancy. Individual differences in looking and emotion were stable across the phases of the still‐face task. Further, individual differences in looking measures from the visual attention task were related to the pattern of looking shown across the phases of the still‐face procedure. Results indicate that individual differences in attentional measures show moderate stability within cognitive and social contexts, and that the ability of infants to shift and disengage looks may affect their ability to regulate interaction in social contexts.