Capacities underlying word learning

Children are strikingly good at learning the meanings of words. Current controversy focuses on the relative importance of different capacities in this learning process including principles of association, low-level attentional mechanisms, special word learning constraints, syntactic cues and theory of mind. We argue that children succeed at word learning because they possess certain conceptual biases about the external world, the ability to infer the referential intentions of others and an appreciation of syntactic cues to word meaning. Support for this view comes from studies exploring the phenomena of fast mapping, the whole object bias, the acquisition of names for entities belonging to different ontological kinds and the effect of lexical contrast. Word learning is not the result of a general associative learning process, nor does it involve specialized constraints. The ability to learn the meanings of words depends on a number of capacities, some of which are specific to language and unique to humans, others of which are potentially shared with other species.     

Wittgenstein and contemporary theories of word learning

Wittgenstein's positions on word learning, rules of use, and the impossibility of a private language, as expounded in his Philosophical Investigations, are examined in relation to issues of early child word learning. Current theoretical positions in the cognitivist mode are contrasted with the social cultural pragmatic approach, and each is compared to the principles that Wittgenstein advanced. Bloom's [(2000). How children learn the meanings of words. Cambridge, MA: MIT Press] version of the cognitivist theory rejects most of the principles that Wittgenstein advanced, relying on innate cognitive endowments to explain children's success in word learning, using the word-referent mapping paradigm. Nelson's “use without meaning” and Tomasello's [(2003). Constructing a language: A usage-based theory of language acquisition. Cambridge, MA: Harvard University Press] social-pragmatic model of learning from use are presented as representative of Wittgensteinian principles that meaning exists in and is inferred from the uses of words within communal activities (“language games” in “forms of life”).     

Embodied attention and word learning by toddlers

Many theories of early word learning begin with the uncertainty inherent to learning a word from its co-occurrence with a visual scene. However, the relevant visual scene for infant word learning is neither from the adult theorist's view nor the mature partner's view, but is rather from the learner's personal view. Here we show that when 18-month old infants interacted with objects in play with their parents, they created moments in which a single object was visually dominant. If parents named the object during these moments of bottom-up selectivity, later forced-choice tests showed that infants learned the name, but did not when naming occurred during a less visually selective moment. The momentary visual input for parents and toddlers was captured via head cameras placed low on each participant's forehead as parents played with and named objects for their infant. Frame-by-frame analyses of the head camera images at and around naming moments were conducted to determine the visual properties at input that were associated with learning. The analyses indicated that learning occurred when bottom-up visual information was clean and uncluttered. The sensory-motor behaviors of infants and parents were also analyzed to determine how their actions on the objects may have created these optimal visual moments for learning. The results are discussed with respect to early word learning, embodied attention, and the social role of parents in early word learning.     

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.     

Infant speech perception bootstraps word learning

By their first birthday, infants can understand many spoken words. Research in cognitive development has long focused on the conceptual changes that accompany word learning, but learning new words also entails perceptual sophistication. Several developmental steps are required as infants learn to segment, identify and represent the phonetic forms of spoken words, and map those word forms to different concepts. We review recent research on how infants' perceptual systems unfold in the service of word learning, from initial sensitivity for speech to the learning of language-specific sound patterns. Building on a recent theoretical framework and emerging new methodologies, we show how speech perception is crucial for word learning, and suggest that it bootstraps the development of a separate but parallel phonological system that links sound to meaning.     

Exclusion constraints facilitate statistical word learning

The roles of linguistic, cognitive, and social-pragmatic processes in word learning are well established. If statistical mechanisms also contribute to word learning, they must interact with these processes; however, there exists little evidence for such mechanistic synergy. Adults use co-occurrence statistics to encode speech-object pairings with detailed sensitivity in stochastic learning environments (Vouloumanos, 2008). Here, we replicate this statistical work with nonspeech sounds and compare the results with the previous speech studies to examine whether exclusion constraints contribute equally to the statistical learning of speech-object and nonspeech-object associations. In environments in which performance could benefit from exclusion, we find a learning advantage for speech over nonspeech, revealing an interaction between statistical and exclusion processes in associative word learning.     

Printed word learning in beginning readers

Three experiments using beginning Dutch readers (7 and 8 years of age) as subjects provide evidence that visually recognizing the unique graphemic structure of words is an important component in word identification, even at rather early stages in learning to read. Only a moderate amount of practice in reading strings of letters was necessary for young children to read the regular spelling faster than an altered spelling that preserved the word sound. In normal beginners this effect appeared regardless of their ability to identify the words the first time; in learning-disabled children, matched in overall reading speed, learning about the graphemic compositions of words seems to proceed at a much slower rate. The results are discussed with regard to the importance of building accurate graphemic entries in the mental lexicon for acquiring fluency in reading.     

Gender differences in adult word learning

In prior work, women were found to outperform men on short-term verbal memory tasks. The goal of the present work was to examine whether gender differences on short-term memory tasks are tied to the involvement of long-term memory in the learning process. In Experiment 1, men and women were compared on their ability to remember phonologically-familiar novel words and phonologically-unfamiliar novel words. Learning of phonologically-familiar novel words (but not of phonologically-unfamiliar novel words) can be supported by long-term phonological knowledge. Results revealed that women outperformed men on phonologically-familiar novel words, but not on phonologically-unfamiliar novel words. In Experiment 2, we replicated Experiment 1 using a within-subjects design, and confirmed gender differences on phonologically-familiar, but not on phonologically-unfamiliar stimuli. These findings are interpreted to suggest that women are more likely than men to recruit native-language phonological knowledge during novel word-learning.     

Perceptual learning and the theory of word perception

Perceptual learning involves the learning of distinctive features and higher-order invariants, learning progressing actively toward the most economical features and structure. Features of words are classified as phonological, graphic, semantic and syntactic. Features of these classes are processed independently and sequentially. Ordering of priorities changes with development, and shifts strategically with the demands of the task. Evidence is presented for priority differences for each class of feature depending on task differences.     

Concreteness effects in bilingual and monolingual word learning

Previous studies have demonstrated that bilingualism can facilitate novel-word learning. However, the mechanisms behind this bilingual advantage remain unknown. Here, we examined whether bilinguals may be more sensitive to semantic information associated with the novel words. To that end, we manipulated the concreteness of the referent in the word-learning paradigm, since concrete words have been shown to activate the semantic system more robustly than abstract words do. The results revealed that the bilingual advantage was stronger for novel words learned in association with concrete rather than abstract referents. These findings suggest that bilingual advantages for word learning may be rooted, at least in part, in bilinguals' greater sensitivity to semantic information during learning.     

Word learning and individual differences in word learning reflected in event-related potentials

Adults learned the meanings of rare words (e.g., gloaming) and then made meaning judgments on pairs of words. The 1st word was a trained rare word, an untrained rare word, or an untrained familiar word. Event-related potentials distinguished trained rare words from both untrained rare and familiar words, first at 140 ms and again at 400-600 ms after onset of the 1st word. These results may point to an episodic memory effect. The 2nd word produced an N400 that distinguished trained and familiar word pairs that were related in meaning from unrelated word pairs. Skilled comprehenders learned more words than less skilled comprehenders and showed a stronger episodic memory effect at 400-600 ms on the 1st word and a stronger N400 effect on the 2nd word. These results suggest that superior word learning among skilled comprehenders may arise from a stronger episodic trace that includes orthographic and meaning information and illustrate, how an episodic theory of word identification can explain reading skill.     

Intentionality and Self-Awareness

In this essay I defend both the individual plausibility and conjoint consistency of two theses. One is the Intentionality Thesis: that all mental states are intentional (object‐directed, exhibit ‘aboutness’). The other is the Self‐Awareness Thesis: that if a subject is aware of an object, then the subject is also aware of being aware of that object. I begin by arguing for the individual prima facie plausibility of both theses. I then go on to consider a regress argument to the effect that the two theses are incompatible. I discuss three responses to that argument, and defend one of them.     

Domain-specific and domain-general constraints on word and sequence learning

The relative influences of language-related and memory-related constraints on the learning of novel words and sequences were examined by comparing individual differences in performance of children with and without specific deficits in either language or working memory. Children recalled lists of words in a Hebbian learning protocol in which occasional lists repeated, yielding improved recall over the course of the task on the repeated lists. The task involved presentation of pictures of common nouns followed immediately by equivalent presentations of the spoken names. The same participants also completed a paired-associate learning task involving word–picture and nonword–picture pairs. Hebbian learning was observed for all groups. Domain-general working memory constrained immediate recall, whereas language abilities impacted recall in the auditory modality only. In addition, working memory constrained paired-associate learning generally, whereas language abilities disproportionately impacted novel word learning. Overall, all of the learning tasks were highly correlated with domain-general working memory. The learning of nonwords was additionally related to general intelligence, phonological short-term memory, language abilities, and implicit learning. The results suggest that distinct associations between language- and memory-related mechanisms support learning of familiar and unfamiliar phonological forms and sequences.     

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.