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Psychological scientists have become increasingly concerned with issues related to methodology and replicability, and infancy researchers in particular face specific challenges related to replicability: For example, high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations. Addressing these concerns, we report on a large-scale, multisite study aimed at (a) assessing the overall replicability of a single theoretically important phenomenon and (b) examining methodological, cultural, and developmental moderators. We focus on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Stimuli of mothers speaking to their infants and to an adult in North American English were created using seminaturalistic laboratory-based audio recordings. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, Australia, and Asia using the three common methods for measuring infants’ discrimination (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35, 95% confidence interval = [0.29, 0.42], which was reliably above zero but smaller than the meta-analytic mean computed from previous literature (0.67). The IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect, and in data from labs using the head-turn preference procedure. Together, these findings replicate the IDS preference but suggest that its magnitude is modulated by development, native-language experience, and testing procedure.

Assessing a child's language in the early years is critical to plan for an early intervention and maximize their learning potential. In a unique pan-Arabic approach to language development, we developed a new Arabic assessment tool, usable by parents and Early Years professionals to screen vocabulary in children between 8 months and 30 months across 17 Arab countries. Departing from the two relevant original Communicative Development Inventory forms (CDI: Words and Gestures and CDI: Words and Sentences, Fenson, Marchman, Thal, Reznick, & Bates, 2007), our Arabic CDI focuses on Words Only (Short Form), and assesses comprehension and production of a list of 100 words in 17 main dialects or Arabic, through a parental report. Data were collected from 436 Egyptian children and 168 children from the remaining 16 countries. Quasi-binomial model fits on Egyptian and Other Dialects comprehension and production data showed that Egyptian vocabulary norms could be reasonably extrapolated to the Other Dialects sample, as a first indication that the tool might be usable across the different countries.

We report on an analysis of spontaneous gesture production in 2-year-old children who come from three countries (Italy, United Kingdom, Australia) and who speak two languages (Italian, English), in an attempt to tease apart the influence of language and culture when comparing children from different cultural and linguistic environments. Eighty-seven monolingual children aged 24-30 months completed an experimental task measuring their comprehension and production of nouns and predicates. The Italian children scored significantly higher than the other groups on all lexical measures. With regard to gestures, British children produced significantly fewer pointing and speech combinations compared to Italian and Australian children, who did not differ from each other. In contrast, Italian children produced significantly more representational gestures than the other two groups. We conclude that spoken language development is primarily influenced by the input language over gesture production, whereas the combination of cultural and language environments affects gesture production.

Young children sometimes attempt an action on an object, which is inappropriate because of the object size--they make scale errors. Existing theories suggest that scale errors may result from immaturities in children's action planning system, which might be overpowered by increased complexity of object representations or developing teleofunctional bias. We used computational modelling to emulate children's learning to associate objects with actions and to select appropriate actions, given object shape and size. A computational Developmental Deep Model of Action and Naming (DDMAN) was built on the dual-route theory of action selection, in which actions on objects are selected via a direct (nonsemantic or visual) route or an indirect (semantic) route. As in case of children, DDMAN produced scale errors: the number of errors was high at the beginning of training and decreased linearly but did not disappear completely. Inspection of emerging object-action associations revealed that these were coarsely organized by shape, hence leading DDMAN to initially select actions based on shape rather than size. With experience, DDMAN gradually learned to use size in addition to shape when selecting actions. Overall, our simulations demonstrate that children's scale errors are a natural consequence of learning to associate objects with actions.

Recent evidence for an evolved fear module in the brain comes from studies showing that adults, children and infants detect evolutionarily threatening stimuli such as snakes faster than non-threatening ones. A decisive argument for a threat detection system efficient early in life would come from data showing, in young infants, a functional threat-detection mechanism in terms of "what" and "where" visual pathways. The present study used a variant of Posner's cuing paradigm, adapted to 7-11-month-olds. On each trial, a threat-irrelevant or a threat-relevant cue was presented (a flower or a snake, i.e., "what"). We measured how fast infants detected these cues and the extent to which they further influenced the spatial allocation of attention ("where"). In line with previous findings, we observed that infants oriented faster towards snake than flower cues. Importantly, a facilitation effect was found at the cued location for flowers but not for snakes, suggesting that these latter cues elicit a broadening of attention and arguing in favour of sophisticated "what-where" connections. These results strongly support the claim that humans have an early propensity to detect evolutionarily threat-relevant stimuli.

Consonants and vowels differ acoustically and articulatorily, but also functionally: Consonants are more relevant for lexical processing, and vowels for prosodic/syntactic processing. These functional biases could be powerful bootstrapping mechanisms for learning language, but their developmental origin remains unclear. The relative importance of consonants and vowels at the onset of lexical acquisition was assessed in French-learning 5-month-olds by testing sensitivity to minimal phonetic changes in their own name. Infants' reactions to mispronunciations revealed sensitivity to vowel but not consonant changes. Vowels were also more salient (on duration and intensity) but less distinct (on spectrally based measures) than consonants. Lastly, vowel (but not consonant) mispronunciation detection was modulated by acoustic factors, in particular spectrally based distance. These results establish that consonant changes do not affect lexical recognition at 5 months, while vowel changes do; the consonant bias observed later in development does not emerge until after 5 months through additional language exposure.

Background: Bilingual children are under-referred due to an ostensible expectation that they lag behind their monolingual peers in their English acquisition. The recommendations of the Royal College of Speech and Language Therapists (RCSLT) state that bilingual children should be assessed in both the languages known by the children. However, despite these recommendations, a majority of speech and language professionals report that they assess bilingual children only in English as bilingual children come from a wide array of language backgrounds and standardized language measures are not available for the majority of these. Moreover, even when such measures do exist, they are not tailored for bilingual children. Aims: It was asked whether a cut-off exists in the proportion of exposure to English at which one should expect a bilingual toddler to perform as well as a monolingual on a test standardized for monolingual English-speaking children. Methods & Procedures: Thirty-five bilingual 2;6-year-olds exposed to British English plus an additional language and 36 British monolingual toddlers were assessed on the auditory component of the Preschool Language Scale, British Picture Vocabulary Scale and an object-naming measure. All parents completed the Oxford Communicative Development Inventory (Oxford CDI) and an exposure questionnaire that assessed the proportion of English in the language input. Where the CDI existed in the bilingual's additional language, these data were also collected. Outcomes & Results: Hierarchical regression analyses found the proportion of exposure to English to be the main predictor of the performance of bilingual toddlers. Bilingual toddlers who received 60% exposure to English or more performed like their monolingual peers on all measures. "K"-means cluster analyses and Levene variance tests confirmed the estimated English exposure cut-off at 60% for all language measures. Finally, for one additional language for which we had multiple participants, additional language CDI production scores were significantly inversely related to the amount of exposure to English. Conclusions & Implications: Typically developing 2;6-year-olds who are bilingual in English and an additional language and who hear English 60% of the time or more, perform equivalently to their typically developing monolingual peers.

A substantial body of evidence demonstrates that infants understand the meaning of spoken words from as early as 6 months. Yet little is known about their ability to do so in the absence of any visual referent, which would offer diagnostic evidence for an adult-like, symbolic interpretation of words and their use in language mediated thought. We used the head-turn preference procedure to examine whether infants can generate implicit meanings from word forms alone as early as 18 months of age, and whether they are sensitive to meaningful relationships between words. In one condition, toddlers were presented with lists of words taken from the same taxonomic category (e.g. animals or body parts). In a second condition, words taken from two other categories (e.g. clothes and food items) were interleaved within the same list. Listening times were found to be longer in the related-category condition than in the mixed-category condition, suggesting that infants extract the meaning of spoken words and are sensitive to the semantic relatedness between these words. Our results show that infants have begun to construct the rudiments of a semantic system based on taxonomic relations even before they enter a period of accelerated vocabulary growth.

Infants in their first year manifest selective patterns of discrimination between languages and between accents of the same language. Prosodic differences are held to be important in whether languages can be discriminated, together with the infant's familiarity with one or both of the accents heard. However, the nature of the prosodic cues that actually facilitate infant discrimination has not been directly examined. We analyzed the accent discrimination of 5- and 7-month-old British English infants, looking for durational features that could predict a range of discrimination results using the Headturn Preference Procedure. We previously found that both 5- and 7-month-olds based in Plymouth could discriminate Plymouth-accented and Welsh-accented English, while 5-month-olds could not discriminate Welsh-accented and Scottish-accented English. Most surprisingly, 7-month-olds failed to discriminate Plymouth-accented and French-accented English. From half of all utterances used in these four experiments, we calculated a range of durational metrics, both globally across utterances and locally at utterance-final edges. Utterance-edge metrics were the relative duration of the final consonant+vowel interval (nfinalCV) and the final vowel alone (nfinalV). Separately for 5- and 7-month-olds, we determined the difference in scores for all durational metrics between: (a) familiar training and novel test utterances and (b) familiar test and novel test utterances. Regression analyses showed unique predictors of discrimination. For 5-month-olds, the predictor was the difference in nfinalCV between familiar training and novel test utterances. For 7-month-olds, the predictor was the difference in finalV between familiar test and novel test utterances. This demonstrates an early sensitivity to precisely those localized timing features that are useful across languages for segmentation. We therefore predict that similar sensitivity should be shown in infants of other language backgrounds.

Following the proposal that consonants are more involved than vowels in coding the lexicon (Nespor, Peña & Mehler, 2003), an early lexical consonant bias was found from age 1;2 in French but an equal sensitivity to consonants and vowels from 1;0 to 2;0 in English. As different tasks were used in French and English, we sought to clarify this ambiguity by using an interactive word-learning study similar to that used in French, with British-English-learning toddlers aged 1;4 and 1;11. Children were taught two CVC labels differing on either a consonant or vowel and tested on their pairing of a third object named with one of the previously taught labels, or part of them. In concert with previous research on British-English toddlers, our results provided no evidence of a general consonant bias. The language-specific mechanisms explaining the differential status for consonants and vowels in lexical development are discussed.

This study used event-related potentials (ERPs) to examine whether we employ the same normalisation mechanisms when processing words spoken with a regional accent or foreign accent. Our results showed that the Phonological Mapping Negativity (PMN) following the onset of the final word of sentences spoken with an unfamiliar regional accent was greater than for those produced in the listener's own accent, whilst PMN for foreign accented speech was reduced. Foreign accents also resulted in a reduction in N400 amplitude when compared to both unfamiliar regional accents and the listener's own accent, with no significant difference found between the N400 of the regional and home accents. These results suggest that regional accent related variations are normalised at the earliest stages of spoken word recognition, requiring less top-down lexical intervention than foreign accents. (Contains 4 figures and 3 tables.)

The recognition of familiar words was evaluated in 20-month-old children raised in a rhotic accent environment to parents that had either rhotic or non-rhotic accents. Using an Intermodal Preferential Looking task children were presented with familiar objects (e.g. "bird") named in their rhotic or non-rhotic form. Children were only able to identify familiar words pronounced in a rhotic accent, irrespective of their parents' accent. This suggests that it is the local community rather than parental input that determines accent preference in the early stages of acquisition. Consequences for the architecture of the early lexicon and for models of word learning are discussed. (Contains 3 tables and 1 figure.)

What are the processes underlying word recognition in the toddler lexicon? Work with adults suggests that, by 5-years of age, hearing a word leads to cascaded activation of other phonologically, semantically and phono-semantically related words (Huang & Snedeker, 2010; Marslen-Wilson & Zwitserlood, 1989). Given substantial differences in children's sensitivity to phonological and semantic relationships between words in the first few years of life (Arias-Trejo & Plunkett, 2010; Newman, Samuelson, & Gupta, 2009; Storkel & Hoover, 2012), the current set of experiments investigated whether children younger than five also show such phono-semantic priming. Using a picture-priming task, Experiments 1 and 2 presented 2-year-olds with phono-semantically related prime-target pairs, where the label for the prime image is phonologically related (Experiment 1--onset CV overlap, Experiment 2--rhyme VC overlap) to a semantic associate of the target label. Across both experiments, toddlers recognised a word faster when this was preceded by a phono-semantically related prime relative to an unrelated prime. Overall, the results provide strong evidence that word recognition involves cascaded processing of phono-semantically related words by 2-years of age. (Contains 2 tables and 1 figure.)

To investigate the interaction between segmental and supra-segmental stress-related information in early word learning, two experiments were conducted with 20- to 24-month-old English-learning children. In an adaptation of the object categorization study designed by Nazzi and Gopnik (2001), children were presented with pairs of novel objects whose labels differed by their initial consonant (Experiment 1) or their medial consonant (Experiment 2). Words were produced with a stress initial (trochaic) or a stress final (iambic) pattern. In both experiments successful word learning was established when the to-be-remembered contrast was embedded in a stressed syllable, but not when embedded in unstressed syllables. This was independent of the overall word pattern, trochaic or iambic, or the location of the phonemic contrast, word-initial or -medial. Results are discussed in light of the use of phonetic information in early lexical acquisition, highlighting the role of lexical stress and ambisyllabicity in early word processing.

This study investigates infants' discrimination abilities for familiar and unfamiliar regional English accents. Using a variation of the head-turn preference procedure, 5-month-old infants demonstrated that they were able to distinguish between their own South-West English accent and an unfamiliar Welsh English accent. However, this distinction was not seen when two unfamiliar accents (Welsh English and Scottish English) were presented to the infants, indicating they had not acquired the general ability to distinguish between regional varieties, but only the distinction between their home accent and unfamiliar regional variations. This ability was also confirmed with 7-month-olds, challenging recent claims that infants lose their sensitivity to dialects at around that age. Taken together, our results argue in favor of an early sensitivity to the intonation system of languages, and to the early learning of accent-specific intonation and potentially segmental patterns. Implications for the development of accent normalization abilities are discussed. (Contains 3 figures, 2 tables, and 4 footnotes.)

Recent data suggest that the first presentation of a foreign accent triggers a delay in word identification, followed by a subsequent adaptation. This study examines under what conditions the delay resumes to baseline level. The delay will be experimentally induced by the presentation of sentences spoken to listeners in a foreign or a regional accent as part of a lexical decision task for words placed at the end of sentences. Using a blocked design of accents presentation, Experiment 1 shows that accent changes cause a temporary perturbation in reaction times, followed by a smaller but long-lasting delay. Experiment 2 shows that the initial perturbation is dependent on participants' expectations about the task. Experiment 3 confirms that the subsequent long-lasting delay in word identification does not habituate after repeated exposure to the same accent. Results suggest that comprehensibility of accented speech, as measured by reaction times, does not benefit from accent exposure, contrary to intelligibility.

Using a name-based categorization task, Nazzi found in 2005 that French-learning 20-month-olds can make use of one-feature consonantal contrasts between new labels but fail to do so with one-feature vocalic contrasts. This asymmetry was interpreted as developmental evidence for the proposal that consonants play a more important role than vowels at the lexical level. In the current study using the same task, we first show that by 30 months French-learning infants can make use of one-feature vocalic contrasts (e.g., /pize/-/pyze/). Second, we show that in a situation where infants must neglect either a consonantal one-feature change or a vocalic one-feature change (e.g., match a /pide/ with either a /tide/ or a /pyde/), both French- and English-learning 30-month-olds choose to neglect the vocalic change rather than the consonantal change. We argue that these results suggest that by 30 months of age, infants still give less weight to vocalic information than to consonantal information in a lexically related task even though they are able to process fine vocalic information. (Contains 3 figures and 3 tables.)

This study examines children's ability to detect accent-related information in connected speech. British English children aged 5 and 7 years old were asked to discriminate between their home accent from an Irish accent or a French accent in a sentence categorization task. Using a preliminary accent rating task with adult listeners, it was first verified that the level of accentedness was similar across the two unfamiliar accents. Results showed that whereas the younger children group behaved just above chance level in this task, the 7-year-old group could reliably distinguish between these variations of their own language, but were significantly better at detecting the foreign accent than the regional accent. These results extend and replicate a previous study (Girard, Floccia, & Goslin, 2008) in which it was found that 5-year-old French children could detect a foreign accent better than a regional accent. The factors underlying the relative lack of awareness for a regional accent as opposed to a foreign accent in childhood are discussed, especially the amount of exposure, the learnability of both types of accents, and a possible difference in the amount of vowels versus consonants variability, for which acoustic measures of vowel formants and plosives voice onset time are provided. (Contains 1 table, 2 footnotes, and 3 figures.)

This study examines children's metaphonological awareness for accent-related information in connected speech. In the first experiment, 5- to 6-year-old French-speaking children were asked to discriminate between Southern and Northern accented French in a sentence categorization task. It was found that these children were not able to reliably distinguish between these native variations of their own language, but were able to distinguish between their own accent and a strong foreign accent in Experiment 2. These findings were also replicated using a speaker discrimination task in Experiment 3, where children were asked to detect pairs of speakers sharing the same accent amongst speaker pairs with different accents. Whilst these experiments have shown that 5- to 6-year-old children do not use non-familiar regional accents as a discriminatory cue, they are able to perceive the differences between accents, as demonstrated in the AX task used in Experiment 4. The factors underlying the relative lack of awareness for a regional accent as opposed to a foreign accent in childhood are discussed, especially regarding the amount of exposure and the learnability of both types of accents.

The influence of development and literacy upon syllabification in French was evaluated by comparing the segmental behavior of 4- to 5-year-old preliterate children and adults using a pause insertion task. Participants were required to repeat bisyllabic words such as "fourmi" ("ant") by inserting a pause between its two syllabic components (/fur/-/mi/). In the first experiment we tested segmentation over a range of 49 double intervocalic consonant clusters. A similar general segmentation behavior was observed in both age groups, with a pattern that fit the predictions from a legality principle-based model of syllabification. Experiment 2 revealed that opacity between phonological and orthographic representations lead to increased ambisyllabic responses and a reduction in segmentation consistency in adults. In total, these findings indicate that syllabic forms are consistently represented from an early age, but that segmentation in metalinguistic tasks is susceptible to contamination from spelling and etymological knowledge.

The processing costs involved in regional accent normalization were evaluated by measuring differences in lexical decision latencies for targets placed at the end of sentences with different French regional accents. Over a series of 6 experiments, the authors examined the time course of comprehension disruption by manipulating the duration and presentation conditions of accented speech. Taken together, the findings of these experiments indicate that regional accent normalization involves a short-term adjustment mechanism that develops as a certain amount of accented signal is available, resulting in a temporary perturbation in speech processing.