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.     

14‐month‐olds exploit verbs’ syntactic contexts to build expectations about novel words

During their second year of life, infants develop a rudimentary understanding of grammatical categories based on their knowledge and use of frequent function words. The current study inquired whether, at only 14 months of age, infants can track co‐occurrence patterns between function words and content words (e.g., determiners can precede nouns, and pronouns can precede verbs), and use these previously encountered syntactic contexts to build expectations about which function words can co‐occur with novel words. Using a habituation paradigm, French‐learning 14‐month‐olds were presented with utterances containing two novel words preceded by function words (either two determiners in the Novel Nouns condition or two pronouns in the Novel Verbs conditions). We found that at test, infants looked longer during trials in which the novel words occurred in an unexpected syntactic context (following a pronoun for infants in the Novel Nouns condition and following a determiner for infants in the pooled analysis of the three Novel Verbs conditions). Hence, our results confirm previous findings on infants’ sensitivity to noun contexts and most importantly demonstrate that their sensitivity to the co‐occurrence of verbs with pronouns begins much earlier than previously understood.     

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.     

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.     

Language Experience Shapes the Development of the Mutual Exclusivity Bias

Halberda (2003) demonstrated that 17‐month‐old infants, but not 14‐ or 16‐month‐olds, use a strategy known as mutual exclusivity (ME) to identify the meanings of new words. When 17‐month‐olds were presented with a novel word in an intermodal preferential looking task, they preferentially fixated a novel object over an object for which they already had a name. We explored whether the development of this word‐learning strategy is driven by children’s experience of hearing only one name for each referent in their environment by comparing the behavior of infants from monolingual and bilingual homes. Monolingual infants aged 17–22 months showed clear evidence of using an ME strategy, in that they preferentially fixated the novel object when they were asked to “look at the dax.” Bilingual infants of the same age and vocabulary size failed to show a similar pattern of behavior. We suggest that children who are raised with more than one language fail to develop an ME strategy in parallel with monolingual infants because development of the bias is a consequence of the monolingual child’s everyday experiences with words.     

Familiarity plays a small role in noun comprehension at 12–18 months

Infants amass thousands of hours of experience with particular items, each of which is representative of a broader category that often shares perceptual features. Robust word comprehension requires generalizing known labels to new category members. While young infants have been found to look at common nouns when they are named aloud, the role of item familiarity has not been well examined. This study compares 12‐ to 18‐month‐olds’ word comprehension in the context of pairs of their own items (e.g., photographs of their own shoe and ball) versus new tokens from the same category (e.g., a new shoe and ball). Our results replicate previous work showing that noun comprehension improves rapidly over the second year, while also suggesting that item familiarity appears to play a far smaller role in comprehension in this age range. This in turn suggests that even before age 2, ready generalization beyond particular experiences is an intrinsic component of lexical development.     

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.     

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.     

Finding the Signal by Adding Noise: The Role of Noncontrastive Phonetic Variability in Early Word Learning

It is well attested that 14‐month‐olds have difficulty learning similar sounding words (e.g., bih/dih), despite their excellent phonetic discrimination abilities. By contrast, Rost and McMurray (2009) recently demonstrated that 14‐month‐olds’ minimal‐pair learning can be improved by the presentation of words by multiple talkers. This study investigates which components of the variability found in multitalker input improved infants’ processing, assessing both the phonologically contrastive aspects of the speech stream and phonologically irrelevant indexical and suprasegmental aspects. In the first two experiments, speaker was held constant while cues to word‐initial voicing were systematically manipulated. Infants failed in both cases. The third experiment introduced variability in speaker, but voicing cues were invariant within each category. Infants in this condition learned the words. We conclude that aspects of the speech signal that have been typically thought of as noise are in fact valuable information—signal—for the young word learner.     

Developmental Changes in Infants’ Ability to Cope with Dialect Variation in Word Recognition

Toward the end of their first year of life, infants’ overly specified word representations are thought to give way to more abstract ones, which helps them to better cope with variation not relevant to word identity (e.g., voice and affect). This developmental change may help infants process the ambient language more efficiently, thus enabling rapid gains in vocabulary growth. One particular kind of variability that infants must accommodate is that of dialectal accent, because most children will encounter speakers from different regions and backgrounds. In this study, we explored developmental changes in infants’ ability to recognize words in continuous speech by familiarizing them with words spoken by a speaker of their own region (North Midland‐American English) or a different region (Southern Ontario Canadian English), and testing them with passages spoken by a speaker of the opposite dialectal accent. Our results demonstrate that 12‐ but not 9‐month‐olds readily recognize words in the face of dialectal variation.     

One is Not Enough: Multiple Exemplars Facilitate Infants' Generalizations of Novel Properties

Across three experiments, we examined 9‐ and 11‐month‐olds' mappings of novel sound properties to novel animal categories. Infants were familiarized with novel animal–novel sound pairings (e.g., Animal A [red]–Sound 1) and then tested on: (1) their acquisition of the original pairing and (2) their generalization of the sound property to a new member of a familiarized category (e.g., Animal A [blue]–Sound 1). When familiarized with a single exemplar of a category, 11‐month‐olds showed no evidence of acquiring or generalizing the animal–sound pairings. In contrast, 11‐month‐olds learnt the original animal–sound mappings and generalized the sound property to a novel member of that category when familiarized with multiple exemplars of a category. Finally, when familiarized with multiple exemplars, 9‐month‐old infants learnt the original animal–sound pairing, but did not extend the novel sound property. The results of these experiments provide evidence for developmental differences in the facilitative role of multiple exemplars in promoting the learning and generalization of information.     

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.     

Functional Parallelism of Detailed and Rough Speech Processing at the End of Infancy

Although realization of the same speech sound is far from being consistent across different contexts, speech recognition has to rely on phonetic detail in order to detect words. So far, it appeared that young infants cannot avoid noticing subtle speech sound variation whenever it occurs. Only later on, they are able to tolerate speech sound variation in some word recognition tasks. Here, we test whether this ability is associated with the time infants start storing their first word forms. We recorded event‐related potentials (ERPs) in a priming paradigm. German words (targets) followed syllables (primes) with a different amount of phoneme overlap. We tested infants at three, six, and nine months after birth. ERPs reflected sensitivity to prime‐target variation in a single phoneme in three‐month‐olds, tolerance to this in six‐month‐olds, and both processing aspects in nine‐month‐olds. Our findings reveal individual developmental priorities for different aspects of speech processing, with very detailed speech processing dominating at around 3 months, rough processing dominating at around half a year after birth, and an architecture of parallel rough and detailed processing at around 9 months. Functional parallelism at the end of infancy might explain the heterogeneous pattern of results regarding the degree of acoustic detail that toddlers appear to consider at different ages and across different paradigms.     

Perceptual Organization Based on Common Region in Infancy

We examined whether infants organize information according to the newly proposed principle of common region, which states that elements within a region are grouped together and separated from those of other regions. In Experiment 1, 6‐ to 7‐month‐olds exhibited sensitivity to regions by discriminating between the displacement of an element within a region versus across regions. In Experiments 2 (6‐ to 7‐month‐olds) and 3 (3‐ to 4‐month‐olds), infants who were habituated to 2 elements in each of 2 regions subsequently discriminated between a familiar and novel grouping in familiar and novel regions. Thus, infants as young as 3 to 4 months of age are not only sensitive to regions in visual images, but also use these regions to group elements in accord with the principle of common region. Because common region analysis is critical to such basic visual functions as figure‐ground and object segregation, these results suggest that the organizational mechanism that underlies many vital visual functions is already operational by 3 to 4 months of age.     

A Sex Difference in Mental Rotation in Infants: Convergent Evidence

Quinn and Liben (2008) reported a sex difference on a mental rotation task in which 3‐ to 4‐month‐olds were familiarized with a shape in different rotations and then tested with a novel rotation of the familiar shape and its mirror image. As a group, males but not females showed a significant preference for the mirror image, a pattern paralleled at the individual level (with most males but less than half the females showing the preference). Experiment 1 examined a possible explanation for this performance difference, namely, that females were more sensitive to the angular differences in the familiarized shape. Three‐ to 4‐month‐olds were given a discrimination task involving familiarization with a shape at a given rotation and preference testing with the shape in the familiarized versus a novel rotation. Females and males preferred the novel rotation, with no sex difference observed. This finding did not provide support for the suggestion that the sex difference in mental rotation is explained by differential sensitivity to angular rotation. Experiment 2 revealed that the sex difference in mental rotation is observed in 6‐ to 7‐month‐olds and 9‐ to 10‐month‐olds, suggesting that a sex difference in mental rotation is present at multiple ages during infancy.     

Six‐Month‐Olds Comprehend Words That Refer to Parts of the Body

Comprehending spoken words requires a lexicon of sound patterns and knowledge of their referents in the world. Tincoff and Jusczyk (1999) demonstrated that 6‐month‐olds link the sound patterns “Mommy” and “Daddy” to video images of their parents, but not to other adults. This finding suggests that comprehension emerges at this young age and might take the form of very specific word‐world links, as in “Mommy” referring only to the infant’s mother and “Daddy” referring only to the infant’s father. The current study was designed to investigate if 6‐month‐olds also show evidence of comprehending words that can refer to categories of objects. The results show that 6‐month‐olds link the sound patterns “hand” and “feet” to videos of an adult’s hand and feet. This finding suggests that very early comprehension has a capacity beyond specific, one‐to‐one, associations. Future research will need to consider how developing categorization abilities, social experiences, and parent word use influence the beginnings of word comprehension.     

Emergence of a consonant bias during the first year of life: New evidence from own‐name recognition

Recent evidence suggests that during the first year of life, a preference for consonant information during lexical processing (consonant bias) emerges, at least for some languages like French. Our study investigated the factors involved in this emergence as well as the developmental consequences for variation in consonant bias emergence. In a series of experiments, we measured 5‐, 8‐, and 11‐month‐old French‐learning infants orientation times to a consonant or vowel mispronunciation of their own name, which is one of the few word forms familiar to infants at this young age. Both 5‐ and 8‐month‐olds oriented longer to vowel mispronunciations, but 11‐month‐olds showed a different pattern, initially orienting longer to consonant mispronunciations. We interpret these results as further evidence of an initial vowel bias, with consonant bias emergence by 11 months. Neither acoustic‐phonetic nor lexical factors predicted preferences in 8‐ and 11‐month‐olds. Finally, counter to our predictions, a vowel bias at the time of test for 11‐month‐olds was related to later productive vocabulary outcomes.     

The Influence of Labels,Non‐Labeling Sounds,and Source of Auditory Input on 9‐ and 15‐Month‐Olds' Object Categorization

This experiment examines the joint influence of auditory and social cues on infants' basic‐level and global categorization. Nine‐ and fifteen‐month‐olds were familiarized to a series of category exemplars in an object‐examining task. Objects were introduced with a labeling phrase, a non‐labeling sound, or no sound, and auditory input was presented orally by the experimenter or played on a hidden voice recorder. Novel objects from the familiarized category and a contrasting category were then presented. Results of analyses performed on novelty preference scores indicated that infants demonstrated basic‐level categorization in all conditions. However, infants at both age levels only demonstrated global categorization when labeling phrases were introduced. In addition, labels led to global categorization in 9‐month‐olds regardless of the source of those labels; however, labels only led to global categorization in 15‐month‐olds when the labels were presented orally by the experimenter.     

Second‐Order Correlation Learning of Dynamic Stimuli: Evidence from Infants and Computational Modeling

We present two habituation experiments that examined 20‐ and 26‐month‐olds’ ability to engage in second‐order correlation learning for static and dynamic features, whereby learned associations between two pairs of features (e.g., P and Q, P and R) are generalized to the features that were not presented together (e.g., Q and R). We also present results from an associative learning mechanism that was implemented as an autoencoder parallel distributed processing (PDP) network in which second‐order correlation learning is shown to be an emergent property of the dynamics of the network. The experiments and simulation demonstrate that 20‐ and 26‐month‐olds as well as neural networks are capable of second‐order correlation learning in a category context for internal features of dynamic objects. However, the model predicts—and Experiment 3 demonstrates—that 20‐ and 26‐month‐olds are unable to encode second‐order correlations in a noncategory context for dynamic objects with internal features. It is proposed that the ability to learn second‐order correlations represents a powerful but as yet unexplored process for generalization in the first years of life.     

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.