Word recognition and learning in signing deaf toddlers.

Word learning is one of the first steps into language, and vocabulary knowledge predicts reading, speaking, and writing ability. There are several pathways to word learning and little is known about how they differ. Previous research has investigated paired-associate (PAL) and cross-situational word learning (CSWL) separately, limiting the understanding of how the learning process compares across the two. In PAL, the roles of word familiarity and working memory have been thoroughly examined, but these same factors have received very little attention in CSWL. We randomly assigned 126 monolingual adults to PAL or CSWL. In each task, names of 12 novel objects were learned (six familiar words, six unfamiliar words). Logistic mixed-effects models examined whether word-learning paradigm, word type and working memory (measured with a backward digit-span task) predicted learning. Results suggest better learning performance in PAL and on familiar words. Working memory predicted word learning across paradigms, but no interactions were found between any of the predictors. This suggests that PAL is easier than CSWL, likely because of reduced ambiguity between the word and the referent, but that learning across both paradigms is equally enhanced by word familiarity, and similarly supported by working memory.

Talker variability and its effects on speech perception is an issue of central importance in word recognition research, and it is known that familiarity with a speaker’s voice improves recognition of novel words [Nygaard et al., Psych. Sci. 5, 42–46 (1994)]. In an investigation of how talker variability interacts with lexical status in the recognition of both familiar and unfamiliar words, listeners performed a closed-set identification task. A visual prime of four potential responses consisting of words and nonsense words that differed minimally phonologically was presented, followed by the audio target stimulus for identification using a response box. The experiment consisted of three 100-trial blocks. The trials were blocked according to talker variability (first block, single talker; second block, multiple talkers; and third block, single talker). Lexical status of the target stimulus varied within trials. Response times were also collected. Listeners performed better when the target item was a word in both the single and the multiple talker conditions. No significant interaction between talker variability and lexical status was found. The results suggest that for listeners lexical status is far more important than talker variability during word recognition.

Two issues were investigated: the first examined the relationships among accuracy and latency of word recognition and comprehension by non-fluent readers, and the second examined whether component letter or holistic processing was used in word recognition by these same readers. Speed and accuracy of word recognition were measured on individual words. Literal comprehension was measured for the same words presented in meaningful context. The unit of perception was measured by the relationship between latency of word recognition and word length. If students were using component processing, latency would increase with word length, but if holistic processing were used, there would be no increase in latency with length. Results of this study indicated that accuracy and latency were each significantly related to comprehension for both first- and second-grade words, with evidence for latency influencing comprehension scores to a greater extent on the first-grade words. With regard to the unit of perception, in general there was evidence of component letter processing for all subjects with the highly accurate readers showing a tendency towards more holistic processing.

Learners of lexical tone languages (e.g., Mandarin) develop sensitivity to tonal contrasts and recognize pitch-matched, but not pitch-mismatched, familiar words by 11 months. Learners of non-tone languages (e.g., English) also show a tendency to treat pitch patterns as lexically contrastive up to about 18 months. In this study, we examined if this early-developing capacity to lexically encode pitch variations enables infants to acquire a pitch accent system, in which pitch-based lexical contrasts are obscured by the interaction of lexical and non-lexical (i.e., intonational) features. Eighteen 17-month-olds learning Tokyo Japanese were tested on their recognition of familiar words with the expected pitch or the lexically opposite pitch pattern. In early trials, infants were faster in shifting their eyegaze from the distractor object to the target object than in shifting from the target to distractor in the pitch-matched condition. In later trials, however, infants showed faster distractor-to-target than target-to-distractor shifts in both the pitch-matched and pitch-mismatched conditions. We interpret these results to mean that, in a pitch-accent system, the ability to use pitch variations to recognize words is still in a nascent state at 17 months.

Building a lexicon is a necessary step in the process of language acquisition. The emergence and development of vocabulary have usually been observed in naturalistic settings through their external manifestations: the first attempts at producing words, and the various signs showing that an infant comprehends words. Naturalistic approaches, however, may underestimate the productive lexicon on one hand, and overestimate the receptive lexicon on the other hand. An experimental approach, using the headturn preference procedure, has been used to show that 11-to-12-month-old French infants can recognize familiar words without specific training (Halle and Boysson-Bardies, 1994). The spontaneous preference for familiar words, interpreted as word recognition, revealed the formation of an early receptive lexicon comprising a significant part of the familiar words that were used. At 12 months, recognition seemed to be firmly established, while it seemed to be just emerging at 11 months. Using the same procedure, the present study examined familiar word recognition in Japanese infants: 12-month-olds, but not 10-month-olds, showed a preference for familiar words, similar in intensity to that shown by 11-month-old French infants. These results are again interpreted as revealing the formation of a nascent receptive lexicon in Japanese infants by 12 months of age. Commonalties and differences between the two language groups are discussed.

The effect of speaker reliability on word learning in monolingual and bilingual children.

Lexical competition that occurs as speech unfolds is a hallmark of adult oral language comprehension crucial to rapid incremental speech processing. This study used pause detection to examine whether lexical competition operates similarly at 7-8years and tested variables that influence "online" lexical activity in adults. Children (n=20) and adults (n=17) were slower to detect pauses in familiar words with later uniqueness points. Faster latencies were obtained for words with late uniqueness points in constraining compared with neutral sentences; no such effect was observed for early unique words. Following exposure to novel competitors ("biscal"), children (n=18) and adults (n=18) showed competition for existing words with early uniqueness points ("biscuit") after 24hr. Thus, online lexical competition effects are remarkably similar across development.

Developmental dyslexia is often characterized by a dual deficit in both word recognition accuracy and general processing speed. While previous research into dyslexic word recognition may have suffered from speed-accuracy trade-off, the present study employed a novel eye-tracking task that is less prone to such confounds. Participants (10 dyslexics and 12 controls) were asked to look at real word stimuli, and to ignore simultaneously presented non-word stimuli, while their eye-movements were recorded. Improvements in word recognition accuracy over time were modeled in terms of a continuous non-linear function. The words' rhyme consistency and the non-words' lexicality (unpronounceable, pronounceable, pseudohomophone) were manipulated within-subjects. Speed-related measures derived from the model fits confirmed generally slower processing in dyslexics, and showed a rhyme consistency effect in both dyslexics and controls. In terms of overall error rate, dyslexics (but not controls) performed less accurately on rhyme-inconsistent words, suggesting a representational deficit for such words in dyslexics. Interestingly, neither group showed a pseudohomophone effect in speed or accuracy, which might call the task-independent pervasiveness of this effect into question. The present results illustrate the importance of distinguishing between speed- vs. accuracy-related effects for our understanding of dyslexic word recognition.

This study aimed to evaluate the impact of static gesture cues on word learning and integration. Following embodied theories of language, gesture-enhanced images displaying the object-use gesture should favor learning and integration of object nouns. Sixty-two adult French speakers learned low-familiarity French nouns of manipulable objects (e.g., "étrille" - currycomb) with gesture-enhanced or neutral images during a short learning session. Immediately after, word recognition (lexical decision) and word production (Picture-Word Interference, PWI) tasks were used to evaluate the impact of image type on word learning and lexical integration, respectively. In the PWI, participants had to name a picture of a familiar object (e.g. "brosse" - brush) while ignoring a written distractor word. Words learned with gesture-enhanced or neutral images were used as distractors. Depending on the condition, they could be semantically related ("étrille" - currycomb) or unrelated ("burin" - chisel) to the target object to name. A control condition with unrelated distractor words not involved in learning ("salière" - salt shaker) was also added. Naming latencies in presence of related distractors, compared to unrelated distractors, indicated whether learned lexical representations engaged in competition during production. Lexical decision results did not show any influence of the image condition used during learning on word recognition. Critically, however, PWI results demonstrated that words trained with gesture-enhanced pictures entailed semantic interference effects during naming. Words trained with neutral pictures did not induce semantic interference. Findings highlight the relevance of gesture cues for lexico-semantic integration of object nouns and suggest considering the role of contextual images in vocabulary acquisition.

The capacity of human infants to discriminate contrasting speech sounds specializes to the native language by the end of the first year of life, when the first signs of word recognition have also been found, using behavioural measures. The extent of voluntary attentional involvement in such word recognition has not been explored, however, nor do we know what its neural time-course may be. Here we demonstrate that 11-month-old children shift their attention automatically to familiar words within 250 ms of presentation onset by measuring event-related potentials elicited by familiar and unfamiliar words. A significant modulation of the first negative peak (N200), known to index implicit change detection in adults, was induced by word familiarity in the infants.

The right and left cerebral hemispheres are important for face and word recognition, respectively-a specialization that emerges over human development. The question is whether this bilateral distribution is necessary or whether a single hemisphere, be it left or right, can support both face and word recognition. Here, face and word recognition accuracy in patients (median age 16.7 y) with a single hemisphere following childhood hemispherectomy was compared against matched typical controls. In experiment 1, participants viewed stimuli in central vision. Across both face and word tasks, accuracy of both left and right hemispherectomy patients, while significantly lower than controls' accuracy, averaged above 80% and did not differ from each other. To compare patients' single hemisphere more directly to one hemisphere of controls, in experiment 2, participants viewed stimuli in one visual field to constrain initial processing chiefly to a single (contralateral) hemisphere. Whereas controls had higher word accuracy when words were presented to the right than to the left visual field, there was no field/hemispheric difference for faces. In contrast, left and right hemispherectomy patients, again, showed comparable performance to one another on both face and word recognition, albeit significantly lower than controls. Altogether, the findings indicate that a single developing hemisphere, either left or right, may be sufficiently plastic for comparable representation of faces and words. However, perhaps due to increased competition or "neural crowding," constraining cortical representations to one hemisphere may collectively hamper face and word recognition, relative to that observed in typical development with two hemispheres.

Nonword repetition (NWR) involves the ability to perceive, store, recall and reproduce phonological sequences. These same abilities play a role in word and morpheme learning. Cross-linguistic studies of performance on NWR tasks, word learning, and morpheme learning yield patterns of increased performance on all three tasks as a function of age and language experience. These results are consistent with the idea that there may be universal information-processing mechanisms supporting language learning. Because bilingual children's language experience is divided across two languages, studying performance in two languages on NWR could inform one's understanding of the relationship between information processing and language learning. The primary aims of this study were to compare bilingual language learners' recall of Spanish-like and English-like items on NWR tasks and to assess the relationships between performance on NWR, semantics, and morphology tasks. Sixty-two Hispanic children exposed to English and Spanish were recruited from schools in central Texas, USA. Their parents reported on the children's input and output in both languages. The children completed NWR tasks and short tests of semantics and morphosyntax in both languages. Mixed-model analysis of variance was used to explore direct effects and interactions between the variables of nonword length, language experience, language outcome measures, and cumulative exposure on NWR performance. Children produced the Spanish-like nonwords more accurately than the English-like nonwords. NWR performance was significantly correlated to cumulative language experience in both English and Spanish. There were also significant correlations between NWR and morphosyntax but not semantics. Language knowledge appears to play a role in the task of NWR. The relationship between performance on morphosyntax and NWR tasks indicates children rely on similar language-learning mechanisms to mediate these tasks. More exposure to Spanish may increase abilities to repeat longer nonwords. This knowledge may shift across levels of bilingualism. Further research is needed to understand this relationship, as it is likely to have implications for language teaching or intervention for children with language impairments.

After intensive practice, unfamiliar letter strings become familiar words and reading speed increases strikingly from a slow processing to a fast and with more global recognition of words. While this effect has been well documented at the behavioral level, its neural underpinnings are still unclear. The question is how the brain modulates the activity of the reading network according to the novelty of the items. Several models have proposed that familiar and unfamiliar words are not processed by separate networks but rather by common regions operating differently according to familiarity. This hypothesis has proved difficult to test at the neural level because the effects of familiarity and length on reading occur (a) on a millisecond scale, shorter than the resolution of fMRI and (b) in regions which cannot be isolated with non-invasive EEG or MEG. We overcame these limitations by using invasive intra-cerebral EEG recording in epileptic patients. Neural activity (gamma-band responses, between 50 and 150 Hz) was measured in three major nodes of reading network – left inferior frontal, supramarginal, and inferior temporo-occipital cortices – while patients silently read familiar (words) and unfamiliar (pseudo-words) items of two lengths (short composed of one-syllable vs. long composed of three-syllables). While all items elicited strong neural responses in the three regions, we found that the duration of the neural response increases with length only for pseudo-words, in direct relation to orthographic-to-phonological conversion. Our results validate at the neural level the hypothesis that all words are processed by a common network operating more or less efficiently depending on words’ novelty.

One of the most prominent issues in early cognitive and linguistic development concerns how children figure out meanings of words from hearing them in context, since in many contexts there are multiple words and multiple potential referents for those words. Recent findings concerning on-line sentence comprehension suggest that, within the conversational context, potential referents compete for mappings to words. Three experiments examined whether such competitive processes may play a role in young children's learning of novel adjectives in an artificial word learning task. According to a competitive process view, although young children often mismap adjectives to whole objects rather than the properties of objects, explicitly mentioned familiar words should strongly map to referents consistent with those words and thereby decrease the likelihood of novel words being mismapped to these referents. Experiments 1 and 2 examined the role of the mere mention of familiar words and the role of word order in two year olds' ability to map a novel adjective to a property. Experiment 3 examined these processes in three year olds. The results indicate that lexical competition plays a particularly strong role in helping two year olds map a novel object to a property, whereas syntactic information about form class may also be informative to older children. The results suggest how fundamental processes of lexical competition in on-line word comprehension may give young learners a way to leverage known words in learning new words.

Interfering neighbours: The impact of novel word learning on the identification of visually similar words