The origins and evolution of links between word learning and conceptual organization: new evidence from 11‐month‐olds

How do infants map words to their meaning? How do they discover that different types of words (e.g. noun, adjective) refer to different aspects of the same objects (e.g. category, property)? We have proposed that (1) infants begin with a broad expectation that novel open‐class words (both nouns and adjectives) highlight commonalities (both category‐ and property‐based) among objects, and that (2) this initial expectation is subsequently fine‐tuned through linguistic experience. We examine the first part of this proposal, asking whether 11‐month‐old infants can construe the very same set of objects (e.g. four purple animals) either as members of an object category (e.g. animals) or as embodying a salient object property (e.g. four purple things), and whether naming (with count nouns vs. adjectives) differentially influences their construals. Results support the proposal. Infants treated novel nouns and adjectives identically, mapping both types of words to both category‐ and property‐based commonalities among objects.     

Lexical leverage: category knowledge boosts real‐time novel word recognition in 2‐year‐olds

Recent research suggests that infants tend to add words to their vocabulary that are semantically related to other known words, though it is not clear why this pattern emerges. In this paper, we explore whether infants leverage their existing vocabulary and semantic knowledge when interpreting novel label–object mappings in real time. We initially identified categorical domains for which individual 24‐month‐old infants have relatively higher and lower levels of knowledge, irrespective of overall vocabulary size. Next, we taught infants novel words in these higher and lower knowledge domains and then asked if their subsequent real‐time recognition of these items varied as a function of their category knowledge. While our participants successfully acquired the novel label–object mappings in our task, there were important differences in the way infants recognized these words in real time. Namely, infants showed more robust recognition of high (vs. low) domain knowledge words. These findings suggest that dense semantic structure facilitates early word learning and real‐time novel word recognition.     

A little labeling goes a long way: Semi‐supervised learning in infancy

There is considerable evidence that labeling supports infants' object categorization. Yet in daily life, most of the category exemplars that infants encounter will remain unlabeled. Inspired by recent evidence from machine learning, we propose that infants successfully exploit this sparsely labeled input through “semi‐supervised learning.” Providing only a few labeled exemplars leads infants to initiate the process of categorization, after which they can integrate all subsequent exemplars, labeled or unlabeled, into their evolving category representations. Using a classic novelty preference task, we introduced 2‐year‐old infants (n = 96) to a novel object category, varying whether and when its exemplars were labeled. Infants were equally successful whether all exemplars were labeled (fully supervised condition) or only the first two exemplars were labeled (semi‐supervised condition), but they failed when no exemplars were labeled (unsupervised condition). Furthermore, the timing of the labeling mattered: when the labeled exemplars were provided at the end, rather than the beginning, of familiarization (reversed semi‐supervised condition), infants failed to learn the category. This provides the first evidence of semi‐supervised learning in infancy, revealing that infants excel at learning from exactly the kind of input that they typically receive in acquiring real‐world categories and their names.     

The organization of words and environmental sounds in the second year: Behavioral and electrophysiological evidence

The majority of research examining early auditory‐semantic processing and organization is based on studies of meaningful relations between words and referents. However, a thorough investigation into the fundamental relation between acoustic signals and meaning requires an understanding of how meaning is associated with both lexical and non‐lexical sounds. Indeed, it is unknown how meaningful auditory information that is not lexical (e.g., environmental sounds) is processed and organized in the young brain. To capture the structure of semantic organization for words and environmental sounds, we record event‐related potentials as 20‐month‐olds view images of common nouns (e.g., dog) while hearing words or environmental sounds that match the picture (e.g., “dog” or barking), that are within‐category violations (e.g., “cat” or meowing), or that are between‐category violations (e.g., “pen” or scribbling). Results show both words and environmental sounds exhibit larger negative amplitudes to between‐category violations relative to matches. Unlike words, which show a greater negative response early and consistently to within‐category violations, such an effect for environmental sounds occurs late in semantic processing. Thus, as in adults, the young brain represents semantic relations between words and between environmental sounds, though it more readily differentiates semantically similar words compared to environmental sounds.     

Why Choo‐Choo Is Better Than Train: The Role of Register‐Specific Words in Early Vocabulary Growth

Across languages, lexical items specific to infant‐directed speech (i.e., ‘baby‐talk words’) are characterized by a preponderance of onomatopoeia (or highly iconic words), diminutives, and reduplication. These lexical characteristics may help infants discover the referential nature of words, identify word referents, and segment fluent speech into words. If so, the amount of lexical input containing these properties should predict infants’ rate of vocabulary growth. To test this prediction, we tracked the vocabulary size in 47 English‐learning infants from 9 to 21 months and examined whether the patterns of growth can be related to measures of iconicity, diminutives, and reduplication in the lexical input at 9 months. Our analyses showed that both diminutives and reduplication in the input were associated with vocabulary growth, although measures of iconicity were not. These results are consistent with the hypothesis that phonological properties typical of lexical input in infant‐directed speech play a role in early vocabulary growth.     

The lasting effects of process‐specific versus stimulus‐specific learning during infancy

The capacity to tell the difference between two faces within an infrequently experienced face group (e.g. other species, other race) declines from 6 to 9 months of age unless infants learn to match these faces with individual‐level names. Similarly, the use of individual‐level labels can also facilitate differentiation of a group of non‐face objects (strollers). This early learning leads to increased neural specialization for previously unfamiliar face or object groups. The current investigation aimed to determine whether early conceptual learning between 6 and 9 months leads to sustained behavioral advantages and neural changes in these same children at 4–6 years of age. Results suggest that relative to a control group of children with no previous training and to children with infant category‐level naming experience, children with early individual‐level training exhibited faster response times to human faces. Further, individual‐level training with a face group – but not an object group – led to more adult‐like neural responses for human faces. These results suggest that early individual‐level learning results in long‐lasting process‐specific effects, which benefit categories that continue to be perceived and recognized at the individual level (e.g. human faces).     

Word‐form familiarity bootstraps infant speech segmentation

At about 7 months of age, infants listen longer to sentences containing familiar words – but not deviant pronunciations of familiar words (Jusczyk & Aslin, 1995). This finding suggests that infants are able to segment familiar words from fluent speech and that they store words in sufficient phonological detail to recognize deviations from a familiar word. This finding does not examine whether it is, nevertheless, easier for infants to segment words from sentences when these words sound similar to familiar words. Across three experiments, the present study investigates whether familiarity with a word helps infants segment similar‐sounding words from fluent speech and if they are able to discriminate these similar‐sounding words from other words later on. Results suggest that word‐form familiarity may be a powerful tool bootstrapping further lexical acquisition.     

Beginning readers activate semantics from sub-word orthography

Two experiments assessed whether 7-year-old children activate semantic information from sub-word orthography. Children made category decisions to visually-presented words, some of which contained an embedded word (e.g., hip in ship). In Experiment 1 children were slower and less accurate to classify words if they contained an embedded word related in meaning to the category (e.g., slower to reject ship as a ‘body part’ than an ‘animal’), especially when the embedded word was higher in frequency than the carrier word. This demonstrates that young children activate semantic information from sub-word orthographic representations, and that they do so from the relatively early stages of learning to read. Experiment 2 replicated this effect. Furthermore, we observed semantic interference regardless of whether the embedded word shared its pronunciation with the carrier (e.g., the hip in ship) or not (e.g., the crow in crown), and regardless of its position within the carrier, suggesting that interference was not dependent on phonological mediation. These findings show that by 7-years-of age, children have begun to establish an orthographic system that is capable of activating sub-word orthographic patterns, strong enough to connect with meaning, when reading words silently.     

The vocabulary spurt predicts the emergence of backward semantic inhibition in 18‐month‐old toddlers

The current study examines the relationship between 18‐month‐old toddlers’ vocabulary size and their ability to inhibit attention to no‐longer relevant information using the backward semantic inhibition paradigm. When adults switch attention from one semantic category to another, the former and no‐longer‐relevant semantic category becomes inhibited, and subsequent attention to an item that belongs to the inhibited semantic category is impaired. Here we demonstrate that 18‐month‐olds can inhibit attention to no‐longer relevant semantic categories, but only if they have a relatively large vocabulary. These findings suggest that an increased number of items (word knowledge) in the toddler lexical‐semantic system during the “vocabulary spurt” at 18‐months may be an important driving force behind the emergence of a semantic inhibitory mechanism. Possessing more words in the mental lexicon likely results in the formation of inhibitory links between words, which allow toddlers to select and deselect words and concepts more efficiently. Our findings highlight the role of vocabulary growth in the development of inhibitory processes in the emerging lexical‐semantic system.     

The reciprocal relation between sleep and memory in infancy: Memory‐dependent adjustment of sleep spindles and spindle‐dependent improvement of memories

Sleep spindle activity in infants supports their formation of generalized memories during sleep, indicating that specific sleep processes affect the consolidation of memories early in life. Characteristics of sleep spindles depend on the infant's developmental state and are known to be associated with trait‐like factors such as intelligence. It is, however, largely unknown which state‐like factors affect sleep spindles in infancy. By varying infants’ wake experience in a within‐subject design, here we provide evidence for a learning‐ and memory‐dependent modulation of infant spindle activity. In a lexical‐semantic learning session before a nap, 14‐ to 16‐month‐old infants were exposed to unknown words as labels for exemplars of unknown object categories. In a memory test on the next day, generalization to novel category exemplars was tested. In a nonlearning control session preceding a nap on another day, the same infants heard known words as labels for exemplars of already known categories. Central–parietal fast sleep spindles increased after the encoding of unknown object–word pairings compared to known pairings, evidencing that an infant's spindle activity varies depending on its prior knowledge for newly encoded information. Correlations suggest that enhanced spindle activity was particularly triggered, when similar unknown pairings were not generalized immediately during encoding. The spindle increase triggered by previously not generalized object–word pairings, moreover, boosted the formation of generalized memories for these pairings. Overall, the results provide first evidence for a fine‐tuned regulation of infant sleep quality according to current consolidation requirements, which improves the infant long‐term memory for new experiences.     

Influences of vowel and tone variation on emergent word knowledge: a cross‐linguistic investigation

To learn words, infants must be sensitive to native phonological contrast. While lexical tone predominates as a source of phonemic contrast in human languages, there has been little investigation of the influences of lexical tone on word learning. The present study investigates infants’ sensitivity to tone mispronunciations in two groups of infants. For one group (Chinese learners), tone is phonemic in their native language, and for the second group (English learners), tone is non‐phonemic and constituted suprasegmental variation. In Experiment 1, English learners were trained on novel word–object pairings and tested on their recognition of correct pronunciations, tone and vowel mispronunciations of these words at 18 and 24 months. In Experiment 2a, bilingual English‐Chinese learners were tested on a similar task translated into Chinese at the same age intervals. Results demonstrate that non‐tonal learners treated tonal and vowel substitutions alike as mispronunciations at 18 months but only treated vowel substitutions as mispronunciations at 24 months. Tonal learners treated both tonal and vowel substitutions as mispronunciations at both ages. In Experiment 2b, bilingual non‐tone language learners were tested on the same set of tasks replicating a similar set of results as monolingual non‐tone language learners (Experiment 1). Findings point to an early predisposition to treat tone as a defining characteristic of words regardless of its lexical relevance at 18 months. Between 18 and 24 months, learners appear to ascribe lexical relevance to tone in a language‐specific manner. The current study identifies the influences of tone variation on memories for newly learned words and the time period during which lexical tone – a highly frequent constituent of human languages – actually becomes lexical for early learners. Findings are contextualized with prevailing models of the developing lexicon.     

When Stronger Knowledge Slows You Down: Semantic Relatedness Predicts Children's Co‐Activation of Related Items in a Visual Search Paradigm

A large literature suggests that the organization of words in semantic memory, reflecting meaningful relations among words and the concepts to which they refer, supports many cognitive processes, including memory encoding and retrieval, word learning, and inferential reasoning. The co‐activation of related items has been proposed as a mechanism by which semantic knowledge influences cognition, and contemporary accounts of semantic knowledge propose that this co‐activation is graded—that it depends on how strongly related the items are in semantic memory. Prior research with adults yielded evidence supporting this prediction; however, there is currently no evidence of graded co‐activation early in development. This study provides the first evidence that in children the co‐activation of related items depends on their relational strength in semantic memory. Participants (N = 84, age range: 3–9 years) were asked to identify a target (e.g., bone) amid distractors. Children's responses were slowed down by the presence of a related distractor (e.g., puppy) relative to unrelated distractors (e.g., flower)—suggesting that children co‐activated related items upon hearing the name of the target. Importantly, the degree of this co‐activation was predicted by the strength of the target–distractor relation, such that distractors more strongly related to the targets slowed down children to a larger extent. These findings have important implications for understanding how organized semantic knowledge affects other cognitive processes across development.     

Sensitivity to auditory‐tactile colocation in early infancy

An ability to detect the common location of multisensory stimulation is essential for us to perceive a coherent environment, to represent the interface between the body and the external world, and to act on sensory information. Regarding the tactile environment “at hand”, we need to represent somatosensory stimuli impinging on the skin surface in the same spatial reference frame as distal stimuli, such as those transduced by vision and audition. Across two experiments we investigated whether 6‐ (n = 14; Experiment 1) and 4‐month‐old (n = 14; Experiment 2) infants were sensitive to the colocation of tactile and auditory signals delivered to the hands. We recorded infants’ visual preferences for spatially congruent and incongruent auditory‐tactile events delivered to their hands. At 6 months, infants looked longer toward incongruent stimuli, whilst at 4 months infants looked longer toward congruent stimuli. Thus, even from 4 months of age, infants are sensitive to the colocation of simultaneously presented auditory and tactile stimuli. We conclude that 4‐ and 6‐month‐old infants can represent auditory and tactile stimuli in a common spatial frame of reference. We explain the age‐wise shift in infants’ preferences from congruent to incongruent in terms of an increased preference for novel crossmodal spatial relations based on the accumulation of experience. A comparison of looking preferences across the congruent and incongruent conditions with a unisensory control condition indicates that the ability to perceive auditory‐tactile colocation is based on a crossmodal rather than a supramodal spatial code by 6 months of age at least.     

The origins of word learning: Brain responses of 3‐month‐olds indicate their rapid association of objects and words

The present study explored the origins of word learning in early infancy. Using event‐related potentials (ERP) we monitored the brain activity of 3‐month‐old infants when they were repeatedly exposed to several initially novel words paired consistently with each the same initially novel objects or inconsistently with different objects. Our results provide strong evidence that these young infants extract statistic regularities in the distribution of the co‐occurrences of objects and words extremely quickly. The data suggest that this ability is based on the rapid formation of associations between the neural representations of objects and words, but that the new associations are not retained in long‐term memory until the next day. The type of brain response moreover indicates that, unlike in older infants, in 3‐month‐olds a semantic processing stage is not involved. Their ability to combine words with meaningful information is caused by a primary learning mechanism that enables the formation of proto‐words and acts as a precursor for the acquisition of genuine words.     

Korean deaf adolescents' recognition of written words for taxonomic categories of different levels

Deaf college students seem to have relatively stronger associations from words for taxonomic categories of basic (e.g., snake) to those of super-ordinate (e.g., reptiles) level than vice versa compared with hearing students in word association (Marschark, Convertino, McEvoy & Masteller, 2004). In deciding whether two sequentially presented words for taxonomic categories of different levels are conceptually related, deaf adolescents might therefore have a poorer performance when they see a category name before than when they see it after one of the corresponding exemplar words. Deaf Korean adolescents were found to recognize words for taxonomic categories of super-ordinate level with lower efficiencies than those of basic level. Their accuracy seemed to reflect a reversed typicality effect when they decided that first-presented words for taxonomic categories of basic level were conceptually related to second-presented words for those of super-ordinate level. It was argued that deaf Korean adolescents went through a temporary stage of having iconic representations of several exemplars of the category aroused in working memory before the abstract semantic representation was fully activated when they saw the word for a taxonomic category of super-ordinate level.     

Fourteen‐month‐old infants learn similar‐sounding words

Can infants, in the very first stages of word learning, use their perceptual sensitivity to the phonetics of speech while learning words? Research to date suggests that infants of 14 months cannot learn two similar‐sounding words unless there is substantial contextual support. The current experiment advances our understanding of this failure by testing whether the source of infants’ difficulty lies in the learning or testing phase. Infants were taught to associate two similar‐sounding words with two different objects, and tested using a visual choice method rather than the standard Switch task. The results reveal that 14‐month‐olds are capable of learning and mapping two similar‐sounding labels; they can apply phonetic detail in new words. The findings are discussed in relation to infants’ concurrent failure, and the developmental transition to success, in the Switch task.     

Children remember words from ignorant speakers but do not attach meaning: evidence from event‐related potentials

Although we know much about the conditions under which children demonstrate selective social learning, we have a limited understanding of the cognitive mechanisms by which children's selectivity manifests. Here, we report findings from a brain electrophysiological (ERP) study designed to determine the extent to which words presented by ignorant speakers were later both familiar to children and associated with semantic meaning. Forty‐eight children (mean age = 6.5 years) first experienced novel word training from either a knowledgeable or an ignorant speaker. Children's ERPs were subsequently recorded as they heard a recording of the speaker using the novel word, followed by a picture of either the object the word was paired with during training (congruent) or a distractor object that was also present during training (incongruent). Children trained by a knowledgeable speaker showed both N200 and N400 effects to the incongruent word–referent pairings, thereby suggesting that the novel words were both familiar and bore a semantic association. In contrast, children trained by an ignorant speaker demonstrated only the N200 effect, thereby suggesting that the word–referent links were familiar, but not associated with semantic meaning. These findings provide evidence that selective word learning involves the disruption of processes specifically associated with semantic consolidation of word learning events.     

Developmental trends in auditory processing can provide early predictions of language acquisition in young infants

Auditory processing capabilities at the subcortical level have been hypothesized to impact an individual's development of both language and reading abilities. The present study examined whether auditory processing capabilities relate to language development in healthy 9‐month‐old infants. Participants were 71 infants (31 boys and 40 girls) with both Auditory Brainstem Response (ABR) and language assessments. At 6 weeks and/or 9 months of age, the infants underwent ABR testing using both a standard hearing screening protocol with 30 dB clicks and a second protocol using click pairs separated by 8, 16, and 64‐ms intervals presented at 80 dB. We evaluated the effects of interval duration on ABR latency and amplitude elicited by the second click. At 9 months, language development was assessed via parent report on the Chinese Communicative Development Inventory ‐ Putonghua version (CCDI‐P). Wave V latency z‐scores of the 64‐ms condition at 6 weeks showed strong direct relationships with Wave V latency in the same condition at 9 months. More importantly, shorter Wave V latencies at 9 months showed strong relationships with the CCDI‐P composite consisting of phrases understood, gestures, and words produced. Likewise, infants who had greater decreases in Wave V latencies from 6 weeks to 9 months had higher CCDI‐P composite scores. Females had higher language development scores and shorter Wave V latencies at both ages than males. Interestingly, when the ABR Wave V latencies at both ages were taken into account, the direct effects of gender on language disappeared. In conclusion, these results support the importance of low‐level auditory processing capabilities for early language acquisition in a population of typically developing young infants. Moreover, the auditory brainstem response in this paradigm shows promise as an electrophysiological marker to predict individual differences in language development in young children.     

Association Learning with Own‐ and Other‐race Faces in three‐ and six‐month old infants – A longitudinal study

This longitudinal study assessed 133 Caucasian German infants at 3 and 6 months of age to investigate the influence of own‐race and other‐race faces as visual stimuli on association learning in the visual expectation paradigm (VExP). The study is related to the findings on the other‐race‐effect (ORE) which is said to emerge at 6 months of age. Caucasian faces were used as stimuli of a familiar ethnic category, whereas African faces were used as stimuli of an unfamiliar ethnic category. There was no significant difference between the two stimulus classes in infants' reaction time (RT) to stimulus shifts at 3 months. At 6 months of age, infants' RT decreased significantly in the Caucasian faces condition but not in the African faces condition. These results indicate that the processing of other‐race versus own‐race faces by the age of 6 months, which is also the relevant age for the onset of the ORE, has an important influence on the performance on the VExP. Copyright © 2011 John Wiley & Sons, Ltd.     

义符的类别一致性和家族大小影响形声字的语义加工

采用行为实验和眼动技术考察义符的类别一致性和家族大小对形声字语义加工的影响。结果发现：(1) 在一致性判断和视觉选择中均存在着字词水平的类别一致性效应, 义符同整字类别一致的字容易认知。(2) 义符的家族大小影响形声字的语义加工, 义符家族大, 汉语母语者对形声字的加工更容易采用形旁推理策略。(3) 义符家族的类别一致性影响形声字的语义加工。(4) 义符家族的类别一致性和家族大小效应受义符与整字的类别一致性调节。