Janne von Koss Torkildsen

Productive vocabulary size predicts event-related potential correlates of fast mapping in 20-month-olds

Although it is well documented that children undergo a productive vocabulary spurt late in the second year, it is unclear whether this development is accompanied by equally significant advances in receptive word processing. In the present study, we tested an electrophysiological procedure for assessing receptive word learning in young children, and the impact of productive vocabulary size for performance in this task. We found that 20-month-olds with high productive vocabularies displayed an N400 incongruity effect to violations of trained associations between novel words and pictures, whereas 20-month-olds with low productive vocabularies did not. However, both high and low producers showed an N400 effect for common real words paired with an incongruous object. These findings indicate that there may be substantial differences in receptive fast mapping efficiency between typically developing children who have reached a productive vocabulary spurt and typically developing children who have not yet reached this productive spurt.

Brain dynamics of word familiarization in 20-month-olds: effects of productive vocabulary size.

The present study investigated the brain mechanisms involved during young childrens receptive familiarization with new words, and whether the dynamics of these mechanisms are related to the childs productive vocabulary size. To this end, we recorded event-related potentials (ERPs) from 20-month-old children in a pseudoword repetition task. Results revealed distinct patterns of repetition effects for children with large and small productive vocabularies. High producers showed evidence of recognizing the novel words already after three presentations, while the low producers needed five presentations to display a recognition effect. The familiarization process was manifested in the modulations of two components, the N200-400 and a later fronto-central component, which appeared to increase in amplitude until a certain level of encoding was reached and then decrease with further repetition. These findings suggest a relation between the onset of the productive vocabulary spurt and the rate of receptive word familiarization.

Electrophysiological correlates of auditory semantic priming in 24-month-olds.

Abstract While the N400 component in adults is sensitive to both semantic incongruity and semantic relatedness between stimulus items, the N400 in toddlers has only been shown as an incongruity effect so far. The present event-related potential (ERP) study aimed to investigate whether the N400 in toddlers also indexes semantic relatedness between single words. To address this issue, we developed a unimodal auditory experiment with semantically related and unrelated word pairs, comparable to behavioral semantic priming tasks used with adults. In 24-month-old children, target words which were preceded by a semantically unrelated word elicited a broadly distributed N400-like effect compared to target words which were primed by a semantically related word. For related words, toddlers displayed a negativity in the 200–400xa0ms interval, indicating facilitated lexical-phonological processing. Results of the present study suggest that the N400 in toddlers is functionally equivalent to the adult component in indexing relatedness as well as semantic incongruity between stimulus items. Moreover, the study demonstrates an instrument for investigating semantic relatedness priming in young children, for whom behavioral tasks are often inappropriate.

Advancing our understanding of the link between statistical learning and language acquisition: The need for longitudinal data

Mastery of language can be a struggle for some children. Amongst those that succeed in achieving this feat there is variability in proficiency. Cognitive scientists remain intrigued by this variation. A now substantial body of research suggests that language acquisition is underpinned by a child’s capacity for statistical learning (SL). Moreover, a growing body of research has demonstrated that variability in SL is associated with variability in language proficiency. Yet, there is a striking lack of longitudinal data. To date, there has been no comprehensive investigation of whether a capacity for SL in young children is, in fact, associated with language proficiency in subsequent years. Here we review key studies that have led to the need for this longitudinal research. Advancing the language acquisition debate via longitudinal research has the potential to transform our understanding of typical development as well as disorders such as autism, specific language impairment, and dyslexia.

Brain responses to lexical-semantic priming in children at risk for dyslexia.

Deviances in early event-related potential (ERP) components reflecting auditory and phonological processing are well-documented in children at familial risk for dyslexia. However, little is known about brain responses which index processing in other linguistic domains such as lexicon, semantics and syntax in this group. The present study investigated effects of lexical-semantic priming in 20- and 24-month-olds at-risk for dyslexia and typically developing controls in two ERP experiments. In both experiments an early component assumed to reflect facilitated lexical processing for primed words was enhanced in the at-risk group compared to the control group. Moreover, an N400-like response which was prominent in the control group was attenuated or absent in at-risk children. Results suggest that deficiencies in young children at-risk for dyslexia are not restricted to perceptual and lower-level phonological abilities, but also affect higher order linguistic skills such as lexical and semantic processing.

Laterality across languages: Results from a global dichotic listening study using a smartphone application.

Left-hemispheric language dominance has been suggested by observations in patients with brain damages as early as the 19th century, and has since been confirmed by modern behavioural and brain imaging techniques. Nevertheless, most of these studies have been conducted in small samples with predominantly Anglo-American background, thus limiting generalization and possible differences between cultural and linguistic backgrounds may be obscured. To overcome this limitation, we conducted a global dichotic listening experiment using a smartphone application for remote data collection. The results from over 4,000 participants with more than 60 different language backgrounds showed that left-hemispheric language dominance is indeed a general phenomenon. However, the degree of lateralization appears to be modulated by linguistic background. These results suggest that more emphasis should be placed on cultural/linguistic specificities of psychological phenomena and on the need to collect more diverse samples.

Statistical learning under incidental versus intentional conditions

Statistical learning (SL) studies have shown that participants are able to extract regularities in input they are exposed to without any instruction to do so. This and other findings, such as the fact that participants are often unable to verbalize their acquired knowledge, suggest that SL can occur implicitly or incidentally. Interestingly, several studies using the related paradigms of artificial grammar learning and serial response time tasks have shown that explicit instructions can aid learning under certain conditions. Within the SL literature, however, very few studies have contrasted incidental and intentional learning conditions. The aim of the present study was to investigate the effect of having prior knowledge of the statistical regularities in the input when undertaking a task of visual sequential SL. Specifically, we compared the degree of SL exhibited by participants who were informed (intentional group) versus those who were uninformed (incidental group) about the presence of embedded triplets within a familiarization stream. Somewhat surprisingly, our results revealed that there were no statistically significant differences (and only a small effect size) in the amount of SL exhibited between the intentional versus the incidental groups. We discuss the ways in which this result can be interpreted and suggest that short presentation times for stimuli in the familiarization stream in our study may have limited the opportunity for explicit learning. This suggestion is in line with recent research revealing a statistically significant difference (and a large effect size) between intentional versus incidental groups using a very similar visual sequential SL task, but with longer presentation times. Finally, we outline a number of directions for future research.

Event-related potentials during word mapping to object shape predict toddlers' vocabulary size.

What role does attention to different object properties play in early vocabulary development? This longitudinal study using event-related potentials in combination with behavioral measures investigated 20- and 24-month-olds (n = 38; n = 34; overlapping n = 24) ability to use object shape and object part information in word-object mapping. The N400 component was used to measure semantic priming by images containing shape or detail information. At 20 months, the N400 to words primed by object shape varied in topography and amplitude depending on vocabulary size, and these differences predicted productive vocabulary size at 24 months. At 24 months, when most of the children had vocabularies of several hundred words, the relation between vocabulary size and the N400 effect in a shape context was weaker. Detached object parts did not function as word primes regardless of age or vocabulary size, although the part-objects were identified behaviorally. The behavioral measure, however, also showed relatively poor recognition of the part-objects compared to the shape-objects. These three findings provide new support for the link between shape recognition and early vocabulary development.

Substantial gains in word learning ability between 20 and 24 months: A longitudinal ERP study

This longitudinal ERP study investigated changes in childrens ability to map novel words to novel objects during the dynamic period of vocabulary growth between 20 and 24 months. During this four-month period the children on average tripled their productive vocabulary, an increase which was coupled with changes in the N400 effect to pseudoword-referent associations. Moreover, productive vocabulary size was related to the dynamics of semantic processing during novel word learning. In children with large productive vocabularies, the N400 amplitude was linearly reduced during the five experimental learning trials, consistent with the repetition effect typically seen in adults, while in children with smaller vocabularies the N400 attenuation did not appear until the end of the learning phase. Vocabulary size was related only to modulation of the N400 to pseudowords, not to real words. These findings demonstrate a remarkable development of fast mapping ability between 20 and 24 months.

Does a lack of auditory experience affect sequential learning

To understand the interaction between sensory experiences and cognition, it is critical to investigate the possibility that deprivation in one sensory modality might affect cognition in other modalities. Here we are concerned with the hypothesis that early experience with sound is vital to the development of domain-general sequential processing skills. In line with this hypothesis, a seminal empirical study found that prelingually deaf children had impaired sequence learning in the visual modality. In order to assess the limits of this hypothesis, the current study employed a different visual sequence learning task in an investigation of prelingually deaf children with cochlear implants and normal hearing children. Results showed statistically significant learning in each of the two groups, and no significant difference in the amount of learning between groups. Moreover, there was no association between the age at which the child received their implant (and thus access to electric hearing) and their performance on the sequential learning task. We discuss key differences between our study and the previous study, and argue that the field must reconsider claims about domain-general cognitive impairment resulting from early auditory deprivation.