Lexical competition in young children's word learning

In two experiments, 1.5-year-olds were taught novel words whose sound patterns were phonologically similar to familiar words (novel neighbors) or were not (novel nonneighbors). Learning was tested using a picture-fixation task. In both experiments, children learned the novel nonneighbors but not the novel neighbors. In addition, exposure to the novel neighbors impaired recognition performance on familiar neighbors. Finally, children did not spontaneously use phonological differences to infer that a novel word referred to a novel object. Thus, lexical competition--inhibitory interaction among words in speech comprehension--can prevent children from using their full phonological sensitivity in judging words as novel. These results suggest that word learning in young children, as in adults, relies not only on the discrimination and identification of phonetic categories, but also on evaluating the likelihood that an utterance conveys a new word.     

Developmental differences in children's context-dependent word learning

In this study, 2.5-, 3-, and 4-year-olds (N = 108) participated in a novel noun generalization task in which background context was manipulated. During the learning phase of each trial, children were presented with exemplars in one or multiple background contexts. At the test, children were asked to generalize to a novel exemplar in either the same or a different context. The 2.5-year-olds’ performance was supported by matching contexts; otherwise, children in this age group demonstrated context dependent generalization. The 3-year-olds’ performance was also supported by matching contexts; however, children in this age group were aided by training in multiple contexts as well. Finally, the 4-year-olds demonstrated high performance in all conditions. The results are discussed in terms of the relationship between word learning and memory processes; both general memory development and memory developments specific to word learning (e.g., retention of linguistic labels) are likely to support word learning and generalization.     

The dynamic functions of social cues during children's word learning

Children learn words in a social environment, facilitated in part by social cues from caregivers, such as eye-gaze and gesture. A common assumption is that social cues convey either perceptual or social information, depending on the age of the child. In this review of research on word learning and social cues during early childhood, we propose that (1) the functions of social cues are not categorically perceptual or social, and (2) social cues support word learning in four interdependent ways: by helping children to orient attention, extract relevant information, disambiguate referents, and understand others' referential intent. We conclude with specific recommendations for theory-building and suggest that the dynamic and complex functions of social cues need to be accounted for in any complete theory of word learning.     

Young children's use of range-of-reference information in word learning

An important source of information about a new word's meaning (and its associated lexical class) is its range of reference: the number of objects to which it is extended. Ninety toddlers (mean age = 37 months) participated in a study to determine whether young children can use this information in word learning. When a novel word was presented with unambiguous lexical class cues as either a proper name (i.e. 'His name is DAXY') or an adjective (i.e. 'He is very DAXY'), toddlers interpreted it appropriately, regardless of whether it was applied to one or both members of a pair of identical-looking stuffed animals. They restricted a proper name to the designated animal(s); but they generalized an adjective from the labeled animal(s) to a new animal bearing the same property. However, when the word was presented with no specific lexical class cues (i.e. 'DAXY'), toddlers made significantly different interpretations, depending on the number of referents. When the word was applied to one animal, they restricted it to that animal (consistent with a proper name interpretation); when the word was applied to two animals, they generalized it to a new animal with the property (consistent with an adjective or a restricted count noun interpretation). Range-of-reference information thus provided toddlers with a default cue to the meaning (and associated lexical class) of a novel word.     

Taking stock as theories of word learning take shape

In this paper we consider the perceptual and conceptual contributions that shape early word learning, using research on the shape bias as a case in point. In our view, conceptual, linguistic, social-pragmatic, and perceptual sources of information influence one another powerfully and continuously in the service of word learning throughout infancy and early childhood. We articulate several key points of convergence and divergence between our theoretical perspective and that of the attentional learning account. Finally, we consider the broader implications of this debate for clarifying the forces that constrain development.     

The development of intergroup bias in childhood: how social norms can shape children's racial behaviours

The present research examined the developmental course of racial behaviours in childhood. It tested the hypothesis that White children's expressions of racial prejudice do not necessarily decline in middle childhood due to the development of particular cognitive skills but that instead, as argued by the socio-normative approach, children older than seven will go on expressing prejudiced attitudes under appropriate conditions. This would be explained by the presence of an anti-racism norm, along with the existence of values promoting equal rights, which impede blatant expressions of racism. In the first study 283 White children aged 6-7 and 9-10 years performed a task of resource allocation to White and Black target children in conditions of high (White interviewer was present) or low (White interviewer was absent) salience of the anti-racist norm. The 6- to 7-year-old children discriminated against the Black target in both conditions whereas older children discriminated against the Black child only when the anti-racist norm was not salient. In Study 2, 187 White children aged 6-7 and 9-10 years performed the same resource allocation task in conditions of explicit activation of similarity vs dissimilarity or egalitarian vs merit-based norms regarding race relations. Supporting the hypothesis of the role of racist or anti-racist norms on the expression of intergroup discrimination, results have again shown that 6- to 7-year-old children discriminated against the Black target in both conditions while older children presented significantly different prejudiced/nonprejudiced behaviours consistent with the activated norms. These results were discussed in terms of the need for a reanalysis of the assumptions and research results of the cognitive-developmental theory and of further developments in the socio-normative approach regarding the development of prejudice in childhood.     

Testing a word is not a test of word learning

Although vocabulary acquisition requires children learn names for multiple things, many investigations of word learning mechanisms teach children the name for only one of the objects presented. This is problematic because it is unclear whether children's performance reflects recall of the correct name–object association or simply selection of the only object that was singled out by being the only object named. Children introduced to one novel name may perform at ceiling as they are not required to discriminate on the basis of the name per se, and appear to rapidly learn words following minimal exposure to a single word. We introduced children to four novel objects. For half the children, only one of the objects was named and for the other children, all four objects were named. Only children introduced to one word reliably selected the target object at test. This demonstration highlights the over-simplicity of one-word learning paradigms and the need for a shift in word learning paradigms where more than one word is taught to ensure children disambiguate objects on the basis of their names rather than their degree of salience.     

Real‐world word learning: Exploring children's developing semantic representations of a science term

Assessments of lexical acquisition are often limited to preschool children on forced‐choice comprehension measures. This study assessed the nature of the understandings 30 school‐age children (mean age = 6;7) acquired about the science term eclipse following a naturalistic exposure to a solar eclipse. The knowledge children acquired about eclipses and a control term comet was assessed at three points in time (baseline‐test, 2‐week post‐test and 5‐month post‐test) using a range of assessment tasks (multiple‐choice comprehension, picture‐naming, drawing and a model solar system manipulation task). Children's knowledge at the baseline‐test and 2‐week post‐test was compared with that of 15 adult controls. The analysis focused on the range of knowledge children acquired about eclipses and the relationships between aspects of knowledge they acquired. We found that children acquired extensive knowledge about eclipses, but not comets. At the 2‐week post‐test, the majority of children were able to produce the term eclipse and provided evidence of accurate comprehension and wider conceptual knowledge about solar eclipses, which was retained at the 5‐month post‐test. Further, children's ability to produce the term was related to their acquisition of ‘rich’ semantic and conceptual knowledge.     

Criterion bias and search sequence bias in word recognition

Six experiments that were designed to test the adequacy of criterion bias explanations of the word frequency effect and the semantic priming effect are reported. It was found that criterion bias models correctly predicted higher error rates in a lexical decision task for nonwords that were misspelled versions of high-frequency words (e.g., MOHTER), rather than low-frequency words (e.g., BOHTER). Also correct was the prediction of increased error rates for misspelled words preceded by a semantically related word (e.g., NURSE-DOTCOR). However, in a misspelling decision task (in which the subject must decide whether the stimulus is a word, a misspelled word, or a nonword), it can be argued that criterion bias should be inoperative, since correct responses must be delayed until all orthographic information has been checked; this should eliminate both frequency and semantic priming effects. This was found not to be the case; clear frequency and priming effects were obtained for both words and misspelled words.     

The bilingual advantage in novel word learning

The present study examined whether bilingualism facilitates acquisition of novel words in adults with different language histories. Word-learning performance was tested in monolingual English speakers, early English—Spanish bilinguals, and early English—Mandarin bilinguals. Novel words were phonologically unfamiliar to all participants, and they were acquired in association with their English translations. At testing, both bilingual groups outperformed the monolingual group. These findings indicate that bilingualism facilitates word-learning performance in adults, and they suggest a general bilingual advantage for novel word learning.     

Linguistic context and children's recall in a probe word task

A probe word task was used to test first-, third-, and fifth-grade children's recall of words in varying linguistic contexts. Consistent with expectations based on short-term memory considerations, words that occurred in meaningful sentence contexts were better recalled than those appearing in strings of unrelated words, and words that appeared toward the end of the sentence or string were better recalled than those occurring toward the beginning. At the same time, the effects of prior text on recall, seen clearly in tasks used in constructive memory research, were not present in this short-term memory task. These findings suggest that while within-sentence semantic relational and syntactic information may be used for partial analysis while material is still in working memory, this state does not permit access to already analyzed information in prior text.The authors express appreciation to Richard Schwartz, Ronnie Wilbur, and Harlan Schweer for their suggestions throughout the course of the study.     

The potential for experimenter bias effects in word recognition experiments

Word recognition experiments that involve comparisons between two different matched sets of words allow for possible experimenter bias if there are many equally well-matched pairs to choose from. The possible extent of this bias depends on the experimenter's intuitive knowledge of the likely difficulty of individual items. This is assessed by asking a number of experimenters to decide which of two frequency-matched words would produce the fastest reaction time in a lexical decision experiment, and then comparing their predictions with actual data. All experimenters demonstrated substantial above-chance accuracy, which was unrelated to the amount of experience they had in the field. It was concluded that the experimenters could potentially produce spurious effect sizes ranging from 16 to 38 msec.     

The role of novelty in early word learning

What mechanism implements the mutual exclusivity bias to map novel labels to objects without names? Prominent theoretical accounts of mutual exclusivity (e.g., Markman, 1989, 1990 ) propose that infants are guided by their knowledge of object names. However, the mutual exclusivity constraint could be implemented via monitoring of object novelty (see Merriman, Marazita, & Jarvis, 1995 ). We sought to discriminate between these contrasting explanations across two preferential looking experiments with 22‐month‐olds. In Experiment 1, infants viewed three objects: one name‐known, two name‐unknown. Of the two name‐unknown objects, one was novel, and the other had been previously familiarized. The infants responded to hearing a novel label by increasing attention only to the novel, name‐unknown object. In a second experiment in which the name‐known object was absent, a novel label increased infants’ attention to a novel object beyond baseline preference for novelty. The experiments provide clear evidence for a novelty‐based mechanism. However, differences in the time course of disambiguation across experiments suggest that novelty processing may be influenced by contextual factors.     

Stored word sequences in language learning: the effect of familiarity on children's repetition of four-word combinations

Recent accounts of the development of grammar propose that children remember utterances they hear and draw generalizations over these stored exemplars. This study tested these accounts' assumption that children store utterances as wholes by testing memory for familiar sequences of words. Using a newly available, dense corpus of child-directed speech, we identified frequently occurring chunks in the input (e.g., sit in your chair) and matched them to infrequent sequences (e.g., sit in your truck). We tested young children's ability to produce these sequences in a sentence-repetition test. Three-year-olds (n= 21) and 2-year-olds (n= 17) were significantly more likely to repeat frequent sequences correctly than to repeat infrequent sequences correctly. Moreover, the 3-year-olds were significantly faster to repeat the first three words of an item if they formed part of a chunk (e.g., they were quicker to say sit in your when the following word was chair than when it was truck). We discuss the implications of these results for theories of language development and processing.     

The effects of word class on children's reading and spelling

Children's oral language functioning has been shown to be affected by word class (i.e., content vs. noncontent words). The present study reveals comparable effects on children's written language performance. In spelling and reading, third and fifth graders show faster and more accurate responses to nouns and verbs than to noncontent words of matched length and frequency. Further, when the children's performance is examined in relation to level of reading skill, it is found that the less-skilled readers exhibit a greater content/noncontent differential than do the more skilled readers. The results are discussed with reference to differential access for the two word classes and its implication for both oral and written language functioning.     

The role of comprehension in children's observational learning of a syntactic rule

This experiment tested the hypothesis that there is a relationship between children's comprehension of a syntactic form and the effectiveness of modeling in promoting imitation of that form. Nursery and kindergarten children received pretests for both comprehension and production of reversible passive sentences. Children who produced no passive sentences were classified either as high, intermediate, or low comprehenders on the basis of their comprehension test performance. Within each of these three groups, children were randomly assigned either to a modeling or to a no-modeling control condition. Children in the treatment condition heard a model use passive sentences to describe a series of pictures. As predicted, the imitation post-test scores of these children were significantly related to their comprehension pretest scores. No significant relationship between the post-test scores and the comprehension scores of control subjects was detected. Children exposed to the model in all three comprehension groups received significantly higher post-test scores than did their respective counterparts in the no-modeling condition. These results are discussed in terms of the hypothesis that language learning proceeds from comprehension to imitation to production.     

The role of partial knowledge in statistical word learning

A critical question about the nature of human learning is whether it is an all-or-none or a gradual, accumulative process. Associative and statistical theories of word learning rely critically on the later assumption: that the process of learning a word’s meaning unfolds over time. That is, learning the correct referent for a word involves the accumulation of partial knowledge across multiple instances. Some theories also make an even stronger claim: Partial knowledge of one word–object mapping can speed up the acquisition of other word–object mappings. We present three experiments that test and verify these claims by exposing learners to two consecutive blocks of cross-situational learning, in which half of the words and objects in the second block were those that participants failed to learn in Block 1. In line with an accumulative account, Re-exposure to these mis-mapped items accelerated the acquisition of both previously experienced mappings and wholly new word–object mappings. But how does partial knowledge of some words speed the acquisition of others? We consider two hypotheses. First, partial knowledge of a word could reduce the amount of information required for it to reach threshold, and the supra-threshold mapping could subsequently aid in the acquisition of new mappings. Alternatively, partial knowledge of a word’s meaning could be useful for disambiguating the meanings of other words even before the threshold of learning is reached. We construct and compare computational models embodying each of these hypotheses and show that the latter provides a better explanation of the empirical data.