No Evidence of Robust Noun-Referent Associations in German-Learning 6- to 14-Month-Olds.

Work with the looking-while-listening (LWL-) paradigm suggested that 6-month-old English-learning infants associated several labels for common nouns with pictures of their referents: While one distractor picture was present, infants systematically fixated the named target picture. However, recent work revealed constraints of infants' noun comprehension. The age at which these abilities can be obtained appears to relate to the infants' familiarity with the talker, the target language, and word frequency differences in target-distractor pairs. Here, we present further data to this newly established field of research. We tested 42 monolingual German-learning infants aged 6-14 months by means of the LWL-paradigm. Infants saw two pictures side-by-side on a screen, whilst an unfamiliar male talker named one of both. Overall, infants did not fixate the target picture more than the distractor picture. In line with previous results, infants' performance on the task was higher when target and distractor differed within their word frequency-as operationalized by the parental rating of word exposure. Together, our results add further evidence for constraints on early word learning. They point to cross-linguistic differences in early word learning and strengthen the view that infants might use extra-linguistic cues within the stimulus pairing, such as frequency imbalance, to disambiguate between two potential referents.

Phonemic Training Modulates Early Speech Processing in Pre-reading Children.

Phonemic awareness and rudimentary grapheme knowledge concurrently develop in pre-school age. In a training study, we tried to disentangle the role of both precursor functions of reading for spoken word recognition. Two groups of children exercised with phonemic materials, but only one of both groups learnt corresponding letters to trained phonemes. A control group exercised finger-number associations (non-linguistic training). After the training, we tested how sensitive children were to prime-target variation in word onset priming. A group of young adults took part in the same experiment to provide data from experienced readers. While decision latencies to the targets suggested fine-grained spoken word processing in all groups, event-related potentials (ERPs) indicated that both phonemic training groups processed phonemic variation in more detail than the non-linguistic training group and young adults at early stages of speech processing. Our results indicate temporal plasticity of implicit speech processing in pre-school age as a function of explicit phonemic training.

A Finger-Based Numerical Training Failed to Improve Arithmetic Skills in Kindergarten Children Beyond Effects of an Active Non-numerical Control Training.

It is widely accepted that finger and number representations are associated: many correlations (including longitudinal ones) between finger gnosis/counting and numerical/arithmetical abilities have been reported. However, such correlations do not necessarily imply causal influence of early finger-number training; even in longitudinal designs, mediating variables may be underlying such correlations. Therefore, we investigated whether there may be a causal relation by means of an extensive experimental intervention in which the impact of finger-number training on initial arithmetic skills was tested in kindergarteners to see whether they benefit from the intervention even before they start formal schooling. The experimental group received 50 training sessions altogether for 10 weeks on a daily basis. A control group received phonology training of a similar duration and intensity. All children improved in the arithmetic tasks. To our surprise and contrary to most accounts in the literature, the improvement shown by the experimental training group was not superior to that of the active control group. We discuss conceptual and methodological reasons why the finger-number training employed in this study did not increase the initial arithmetic skills beyond the unspecific effects of the control intervention.

Time and distance estimation in children using an egocentric navigation task.

Navigation crucially depends on the capability to estimate time elapsed and distance covered during movement. From adults it is known that magnitude estimation is subject to characteristic biases. Most intriguing is the regression effect (central tendency), whose strength depends on the stimulus distribution (i.e. stimulus range), a second characteristic of magnitude estimation known as range effect. We examined regression and range effects for time and distance estimation in eleven-year-olds and young adults, using an egocentric virtual navigation task. Regression effects were stronger for distance compared to time and depended on stimulus range. These effects were more pronounced in children compared to adults due to a more heterogeneous performance among the children. Few children showed veridical estimations similar to adults; most children, however, performed less accurate displaying stronger regression effects. Our findings suggest that children use magnitude processing strategies similar to adults, but it seems that these are not yet fully developed in all eleven-year-olds and are further refined throughout adolescence.

ERP evidence for implicit L2 word stress knowledge in listeners of a fixed-stress language.

Languages with contrastive stress, such as English or German, distinguish some words only via the stress status of their syllables, such as "CONtent" and "conTENT" (capitals indicate a stressed syllable). Listeners with a fixed-stress native language, such as Hungarian, have difficulties in explicitly discriminating variation of the stress position in a second language (L2). However, Event-Related Potentials (ERPs) indicate that Hungarian listeners implicitly notice variation from their native fixed-stress pattern. Here we used ERPs to investigate Hungarian listeners' implicit L2 processing. In a cross-modal word fragment priming experiment, we presented spoken stressed and unstressed German word onsets (primes) followed by printed versions of initially stressed and initially unstressed German words (targets). ERPs reflected stress priming exerted by both prime types. This indicates that Hungarian listeners implicitly linked German words with the stress status of the primes. Thus, the formerly described explicit stress discrimination difficulty associated with a fixed-stress native language does not generalize to implicit aspects of L2 word stress processing.

What determines the speed of speech recognition? Evidence from congenitally blind adults.

It is a matter of debate, whether and how improved auditory discrimination abilities enable speeded speech comprehension in congenitally blind adults. Previous research has concentrated on semantic and syntactic aspects of processing. Here we investigated phonologically mediated spoken word access processes by means of word onset priming. Blind adults and age- and gender-matched sighted adults listened to spoken word onsets (primes) followed by complete words (targets). Phonological overlap between primes and targets varied. Blind participants made faster lexical decision responses than sighted participants, yet their speeded responses were not restricted to phonologically overlapping trials. Furthermore, timing of Event Related Potential (ERP) results did not differ between blind and sighted participants. Together these results suggest that blind and sighted listeners are equally fast in implicit phonological encoding and lexical matching mechanisms. It appears that blind adults' speeded speech processing emerges when phonological analysis makes promising word candidates available for further processing. As one possible interpretation, we speculate that lexical selection processes in blind adults do not need to wait for information from the visual domain, while auditory-visual integration mechanisms are mandatorily implemented in speech recognition routines of sighted adults.

Tracking independence and merging of prosodic and phonemic processing across infancy.

Recent evidence suggests division of labor in phonological analysis underlying speech recognition. Adults and children appear to decompose the speech stream into phoneme-relevant information and into syllable stress. Here we investigate whether both speech processing streams develop from a common path in infancy, or whether there are two separate streams from early on. We presented stressed and unstressed syllables (spoken primes) followed by initially stressed early learned disyllabic German words (spoken targets). Stress overlap and phoneme overlap between the primes and the initial syllable of the targets varied orthogonally. We tested infants 3, 6 and 9 months after birth. Event-related potentials (ERPs) revealed stress priming without phoneme priming in the 3-month-olds; phoneme priming without stress priming in the 6-month-olds; and phoneme priming, stress priming as well as an interaction of both in 9-month-olds. In general the present findings reveal that infants start with separate processing streams related to syllable stress and to phoneme-relevant information; and that they need to learn to merge both aspects of speech processing. In particular the present results suggest (i) that phoneme-free prosodic processing dominates in early infancy; (ii) that prosody-free phoneme processing dominates in middle infancy; and (iii) that both types of processing are operating in parallel and can be merged in late infancy.

How space-number associations may be created in preliterate children: six distinct mechanisms.

The directionality of space-number association (SNA) is shaped by cultural experiences. It usually follows the culturally dominant reading direction. Smaller numbers are generally associated with the starting side for reading (left side in Western cultures), while larger numbers are associated with the right endpoint side. However, SNAs consistent with cultural reading directions are present before children can actually read and write. Therefore, these SNAs cannot only be shaped by the direction of children's own reading/writing behavior. We propose six distinct processes - one biological and five cultural/educational - underlying directional SNAs before formal reading acquisition: (i) Brain lateralization, (ii) Monitoring adult reading behavior, (iii) Pretend reading and writing, and rudimentary reading and writing skills, (iv) Dominant attentional directional preferences in a society, not directly related to reading direction, (v) Direct spatial-numerical learning, (vi) Other spatial-directional processes independent of reading direction. In this mini-review, we will differentiate between these processes, elaborate when in development they might emerge, discuss how they may create the SNAs observed in preliterate children and propose how they can be studied in the future.

Phoneme-free prosodic representations are involved in pre-lexical and lexical neurobiological mechanisms underlying spoken word processing.

Recently we reported that spoken stressed and unstressed primes differently modulate Event Related Potentials (ERPs) of spoken initially stressed targets. ERP stress priming was independent of prime-target phoneme overlap. Here we test whether phoneme-free ERP stress priming involves the lexicon. We used German target words with the same onset phonemes but different onset stress, such as MANdel ("almond") and manDAT ("mandate"; capital letters indicate stress). First syllables of those words served as primes. We orthogonally varied prime-target overlap in stress and phonemes. ERP stress priming did neither interact with phoneme priming nor with the stress pattern of the targets. However, polarity of ERP stress priming was reversed to that previously obtained. The present results are evidence for phoneme-free prosodic processing at the lexical level. Together with the previous results they reveal that phoneme-free prosodic representations at the pre-lexical and lexical level are recruited by neurobiological spoken word recognition.

Processing of syllable stress is functionally different from phoneme processing and does not profit from literacy acquisition.

Speech is characterized by phonemes and prosody. Neurocognitive evidence supports the separate processing of each type of information. Therefore, one might suggest individual development of both pathways. In this study, we examine literacy acquisition in middle childhood. Children become aware of the phonemes in speech at that time and refine phoneme processing when they acquire an alphabetic writing system. We test whether an enhanced sensitivity to phonemes in middle childhood extends to other aspects of the speech signal, such as prosody. To investigate prosodic processing, we used stress priming. Spoken stressed and unstressed syllables (primes) preceded spoken German words with stress on the first syllable (targets). We orthogonally varied stress overlap and phoneme overlap between the primes and onsets of the targets. Lexical decisions and Event-Related Potentials (ERPs) for the targets were obtained for pre-reading preschoolers, reading pupils and adults. The behavioral and ERP results were largely comparable across all groups. The fastest responses were observed when the first syllable of the target word shared stress and phonemes with the preceding prime. ERP stress priming and ERP phoneme priming started 200 ms after the target word onset. Bilateral ERP stress priming was characterized by enhanced ERP amplitudes for stress overlap. Left-lateralized ERP phoneme priming replicates previously observed reduced ERP amplitudes for phoneme overlap. Groups differed in the strength of the behavioral phoneme priming and in the late ERP phoneme priming effect. The present results show that enhanced phonological processing in middle childhood is restricted to phonemes and does not extend to prosody. These results are indicative of two parallel processing systems for phonemes and prosody that might follow different developmental trajectories in middle childhood as a function of alphabetic literacy.

ERP correlates of word onset priming in infants and young children.

Using word onset priming with early learned words, we tracked access to phonological representations and predictive phonological processing at 6, 12, 18, and 24 months after birth. Event-Related Potentials (ERPs) were recorded while participants heard German word onsets (primes) followed by disyllabic spoken words (targets). Primes and target onsets were either congruent or incongruent (ma - Mama vs. so - Mama [Engl. 'mommy']). For an adult control group, ERP differences were found for the N100 complex, which has been related to abstract auditory analysis; and for the P350 deflection, which has been related to lexical access. A combined analysis of all infants and young children revealed an immature instance of an N100 effect, suggesting adult-like abstract speech sound processing. A central negativity effect, which had formerly been obtained when adults or older children were engaged in a lexical decision task, suggests that adult-like predictive phonological processing is available early in infancy. However, the absence of a P350-like effect in the infant data suggests that adult-like access to phonological forms is not established in the first two years of life. Taken together, ERPs recorded in word onset priming proved useful in investigating early phonological processing without an explicit behavioral measure.

Learning to read shapes the activation of neural lexical representations in the speech recognition pathway.

It has been demonstrated that written and spoken language processing are tightly linked. Here we focus on the development of this relationship at the time children start reading and writing. We hypothesize that the newly acquired knowledge about graphemes shapes lexical access in neural spoken word recognition. A group of preliterate children (six years old) and two groups of beginning readers (six and eight years old) were tested in a spoken word identification task. Using word onset priming we compared behavioural and neural facilitation for target words in identical prime-target pairs (e.g., mon-monster) and in prime target pairs that varied in the first speech sound (e.g., non-monster, Variation condition). In both groups of beginning readers priming was less effective in the Variation condition than in the Identity condition. This was indexed by less behavioural facilitation and enhanced P350 amplitudes in the event related potentials (ERPs). In the group of preliterate children, by contrast, both conditions did not differ. Together these results reveal that lexical access in beginning readers is based on more acoustic detail than lexical access in preliterate children. The results are discussed in the light of bidirectional speech and print interactions in readers.

Electrophysiological indices of word fragment priming allow characterizing neural stages of speech recognition.

Spoken word onset syllables (prime fragments) have been used to track neurophysiological processing of following written words (targets). Between 300 and 400 ms event-related potentials (ERPs) over the left hemisphere were more positive for targets that did not match their preceding prime fragments (e.g., hun-dragon) compared to matching targets (e.g., dra-dragon). This P350 effect has been related to the activation of modality independent neural word form representations. In the present experiment we set out to characterize neural word processing specific to the auditory domain. Spoken word onset syllables (prime fragments) were followed by spoken words (targets). Reduced amplitudes for matching targets were found for the N100 and the T-complex (100-300 ms), for the P350 (300-400 ms) and for a central negativity starting at 300 ms. The early potentials possibly index the priming of speech sound processing. The P350 replicates previous work with written words. This constitutes further evidence for shared neural word form representations in auditory and visual word recognition. The central negativity might be related to the rapid phonological matching of prime and target; or to the immediate testing of phonological expectations in speech recognition.