Developmental change in children's speech processing of auditory and visual cues: An eyetracking study.

This study investigates how children aged two to eight years (N = 129) and adults (N = 29) use auditory and visual speech for word recognition. The goal was to bridge the gap between apparent successes of visual speech processing in young children in visual-looking tasks, with apparent difficulties of speech processing in older children from explicit behavioural measures. Participants were presented with familiar words in audio-visual (AV), audio-only (A-only) or visual-only (V-only) speech modalities, then presented with target and distractor images, and looking to targets was measured. Adults showed high accuracy, with slightly less target-image looking in the V-only modality. Developmentally, looking was above chance for both AV and A-only modalities, but not in the V-only modality until 6 years of age (earlier on /k/-initial words). Flexible use of visual cues for lexical access develops throughout childhood.

A Shift in the Direction of the Production Effect in Children Aged 2-6 Years.

Research has found mixed evidence for the production effect in childhood. Some studies have found a positive effect of production on word recognition and recall, while others have found the reverse. This paper takes a developmental approach to investigate the production effect. Children aged 2-6 years (n = 150) from a predominantly white population in Ottawa, Canada were trained on familiar words which were either seen, heard or produced, followed by a recall task. Results showed a developmental shift: younger participants showed a reverse production effect, recalling more words that were heard during training, while older children showed the typical production effect, recalling more produced words. The effect of production on recall is not unidirectional and varies by age.

Monolingual and bilingual children's processing of coarticulation cues during spoken word recognition.

Bilingual children cope with a significant amount of phonetic variability when processing speech, and must learn to weigh phonetic cues differently depending on the cues' respective roles in their two languages. For example, vowel nasalization is coarticulatory and contrastive in French, but coarticulatory-only in English. In this study, we extended an investigation of the processing of coarticulation in two- to three-year-old English monolingual children (Zamuner, Moore & Desmeules-Trudel, 2016) to a group of four- to six-year-old English monolingual children and age-matched English-French bilingual children. Using eye tracking, we found that older monolingual children and age-matched bilingual children showed more sensitivity to coarticulation cues than the younger children. Moreover, when comparing the older monolinguals and bilinguals, we found no statistical differences between the two groups. These results offer support for the specification of coarticulation in word representations, and indicate that, in some cases, bilingual children possess language processing skills similar to monolinguals.

Reverse production effect: children recognize novel words better when they are heard rather than produced.

This research investigates the effect of production on 4.5- to 6-year-old children's recognition of newly learned words. In Experiment 1, children were taught four novel words in a produced or heard training condition during a brief training phase. In Experiment 2, children were taught eight novel words, and this time training condition was in a blocked design. Immediately after training, children were tested on their recognition of the trained novel words using a preferential looking paradigm. In both experiments, children recognized novel words that were produced and heard during training, but demonstrated better recognition for items that were heard. These findings are opposite to previous results reported in the literature with adults and children. Our results show that benefits of speech production for word learning are dependent on factors such as task complexity and the developmental stage of the learner.

Toddlers' sensitivity to within-word coarticulation during spoken word recognition: Developmental differences in lexical competition.

To understand speech, listeners need to be able to decode the speech stream into meaningful units. However, coarticulation causes phonemes to differ based on their context. Because coarticulation is an ever-present component of the speech stream, it follows that listeners may exploit this source of information for cues to the identity of the words being spoken. This research investigates the development of listeners' sensitivity to coarticulation cues below the level of the phoneme in spoken word recognition. Using a looking-while-listening paradigm, adults and 2- and 3-year-old children were tested on coarticulation cues that either matched or mismatched the target. Both adults and children predicted upcoming phonemes based on anticipatory coarticulation to make decisions about word identity. The overall results demonstrate that coarticulation cues are a fundamental component of children's spoken word recognition system. However, children did not show the same resolution as adults of the mismatching coarticulation cues and competitor inhibition, indicating that children's processing systems are still developing.

Infants track word forms in early word-object associations.

A central component of language development is word learning. One characterization of this process is that language learners discover objects and then look for word forms to associate with these objects (Mcnamara, 1984; Smith, 2000). Another possibility is that word forms themselves are also important, such that once learned, hearing a familiar word form will lead young word learners to look for an object to associate with it (Juscyzk, 1997). This research investigates the relative weighing of word forms and objects in early word-object associations using the anticipatory eye-movement paradigm (AEM; McMurray & Aslin, 2004). Eighteen-month-old infants and adults were taught novel word-object associations and then tested on ambiguous stimuli that pitted word forms and objects against each other. Results revealed a change in weighing of these components across development. For 18-month-old infants, word forms weighed more in early word-object associative learning, while for adults, objects were more salient. Our results suggest that infants preferentially use word forms to guide the process of word-object association.

Spoken word recognition in a second language: The importance of phonetic details.

Spoken word recognition depends on variations in fine-grained phonetics as listeners decode speech. However, many models of second language (L2) speech perception focus on units such as isolated syllables, and not on words. In two eye-tracking experiments, we investigated how fine-grained phonetic details (i.e. duration of nasalization on contrastive and coarticulatory nasalized vowels in Canadian French) influenced spoken word recognition in an L2, as compared to a group of native (L1) listeners. Results from L2 listeners (English-native speakers) indicated that fine-grained phonetics impacted the recognition of words, i.e. they were able to use nasalization duration variability in a way similar to L1-French listeners, providing evidence that lexical representations can be highly specified in an L2. Specifically, L2 listeners were able to distinguish minimal word pairs (differentiated by the presence of phonological vowel nasalization in French) and were able to use variability in a way approximating L1-French listeners. Furthermore, the robustness of the French "nasal vowel" category in L2 listeners depended on age of exposure. Early bilinguals displayed greater sensitivity to some ambiguity in the stimuli than late bilinguals, suggesting that early bilinguals had greater sensitivity to small variations in the signal and thus better knowledge of the phonetic cue associated with phonological vowel nasalization in French, similarly to L1 listeners.

Phonotactic probabilities at the onset of language development: speech production and word position.

PURPOSE: To examine the role of phonotactic probabilities at the onset of language development, in a new language (Dutch), while controlling for word position. METHOD: Using a nonword imitation task, 64 Dutch-learning children (age 2;2-2;8 [years;months]) were tested on how they imitated segments in low- and high-phonotactic probability environments, in word-initial and word-final position. The relationship between phonological representations and vocabulary development was examined by comparing children's performance with their receptive and expressive vocabularies. RESULTS: Segments in high-phonotactic probability environments were at an advantage in production, in both word-initial and word-final position. Significant correlations were found between vocabulary size and children's mean segment repetition accuracy for word-initial position, but not in word-final position. CONCLUSION: The results indicate that phonological representations are mediated not only by children's developing vocabularies but also by the structure of children's emerging lexicons.

Gradient and categorical patterns of spoken-word recognition and processing of phonetic details.

The speech signal is inherently rich, and this reflects complexities of speech articulation. During spoken-word recognition, listeners must process time-dependent perceptual cues, and the role that these cues play varies depending on the phonological status of the sounds across languages. For example, Canadian French has both phonologically nasal vowels (i.e., contrastive) and coarticulatorily nasalized vowels, as opposed to English, which only has coarticulatorily nasalized vowels. We investigated how vowel nasalization duration, a time-dependent phonetic cue to the French nasal contrast, affects spoken-word recognition. Using eye tracking in two visual world paradigm experiments, the results show that fine-grained phonetic information is important for lexical recognition, and that lexical access is dependent on small variations in the signal. The results also show gradient interpretation of ambiguous vowel nasalization despite the phonemic distinction between phonological nasal vowels and coarticulatorily nasalized vowels in Canadian French. Gradience was found when words were ambiguous, and interpretation was more categorical when words were unambiguous. These results support the hypothesis of gradient interpretation of phonetic cues for ambiguously produced stimuli and the storage of coarticulatory information in phono-lexical representations for a language that has a phonological contrast for nasality (i.e., French).

Correction to: Gradient and categorical patterns of spoken-word recognition and processing of phonetic details.

The Publisher regrets that, due to a typesetting mistake, it has now become necessary to make the following corrections: All phonetic transcriptions (between square brackets and slashes) should be corrected and displayed as follows, in the same font.

The many facets of speech production and its complex effects on phonological processing.

In our commentary, we discuss two additional points about developmental speech production. First, we suggest that more precision is needed to accurately describe 'speech production' processes, and we suggest that hierarchical constructs from the adult literatures on articulatory phonology and speech motor control may be applicable to infants as well. Second, we discuss the implications from data that indicate that the effects of production are subject to task-, attentional-, linguistic-, and experience-related demands.

Sensitivity to Word-Final Phonotactics in 9- to 16-Month-Old Infants.

Previous research has shown that infants begin to display sensitivities to language-specific phonotactics and probabilistic phonotactics at around 9 months of age. However, certain phonotactic patterns have not yet been examined, such as contrast neutralization, in which phonemic contrasts are neutralized typically in syllable- or word-final position. Thus, the acquisition of contrast neutralization is dependent on infants' ability to perceive certain contrasts in final position. The studies reported here test infants' sensitivity to voicing neutralization in word-final position and infants' discrimination of voicing and place of articulation (POA) contrasts in word-initial and word-final position. Nine and 11-month-old Dutch-learning infants showed no preference for legal versus illegal voicing phonotactics that were contrasted in word-final position. Furthermore, 10-month-old infants showed no discrimination of voicing or POA contrasts in word-final position, whereas they did show sensitivity to the same contrasts in word-initial position. By 16 months, infants were able to discriminate POA contrasts in word-final position, although showing no discrimination of the word-final voicing contrast. These findings have broad implications for models of how learners acquire the phonological structures of their language, for the types of phonotactic structures to which infants are presumed to be sensitive, and for the relative sensitivity to phonemic distinctions by syllable and word position during acquisition.

Understanding the developing sound system: interactions between sounds and words.

UNLABELLED: Over the course of the first 2 years of life, infants are learning a great deal about the sound system of their native language. Acquiring the sound system requires the infant to learn about sounds and their distributions, sound combinations, and prosodic information, such as syllables, rhythm, and stress. These aspects of the phonological system are being learned simultaneously as the infant experiences the language around him or her. What binds all of the phonological units is the context in which they occur, namely, words. In this review, we explore the development of phonetics and phonology by showcasing the interactive nature of the developing lexicon and sound system with a focus on perception. We first review seminal research in the foundations of phonological development. We then discuss early word recognition and learning followed by a discussion of phonological and lexical representations. We conclude by discussing the interactive nature of lexical and phonological representations and highlight some further directions for exploring the developing sound system. WIREs Cogn Sci 2014, 5:589-602. doi: 10.1002/wcs.1307 For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article.

The structure and nature of phonological neighbourhoods in children's early lexicons.

This research examines phonological neighbourhoods in the lexicons of children acquiring English. Analyses of neighbourhood densities were done on children's earliest words and on a corpus of spontaneous speech, used to measure neighbours in the target language. Neighbourhood densities were analyzed for words created by changing segments in word-onset position (rhyme neighbours as in pin/bin), vowel position (consonant neighbours as in pin/pan/) and word-offset position (lead neighbours as in pin/pit). Results indicated that neighbours in children's early lexicons are significantly more often distinguished in word-onset position (rhyme neighbours) and significantly less often distinguished in word-offset position (lead neighbours). Moreover, patterns in child language are more extreme than in the target language. Findings are discussed within the PRIMIR framework (Processing Rich Information from Multidimensional Interaction Representations; Werker & Curtin, 2005). It is argued that early perceptual sensitivity aids lexical acquisition, supporting continuity across speech perception and lexical acquisition.

Phonotactic probabilities in young children's speech production.

This research explores the role of phonotactic probability in two-year-olds' production of coda consonants. Twenty-nine children were asked to repeat CVC non-words that were used as labels for pictures of imaginary animals. The CVC non-words were controlled for their phonotactic probabilities, neighbourhood densities, word-likelihood ratings, and contained the identical coda across low and high phonotactic probability pairs. This allowed for comparisons of children's productions of the same coda consonant in low and high phonotactic probability environments. Children were significantly more likely to produce the same coda in high phonotactic probability non-words than in low phonotactic probability non-words. These results are consistent with the hypothesis that phonotactic probability is a predictor of coda production in English. Moreover, this finding provides further evidence for the role of the input and distribution of sound patterns in the ambient language as a basis for phonological acquisition.