Laurel Fais

Infant-directed speech supports phonetic category learning in English and Japanese.

Across the first year of life, infants show decreased sensitivity to phonetic differences not used in the native language [Werker, J. F., & Tees, R. C. (1984). Cross-language speech perception: evidence for perceptual reorganization during the first year of life. Infant Behaviour and Development, 7, 49-63]. In an artificial language learning manipulation, Maye, Werker, and Gerken [Maye, J., Werker, J. F., & Gerken, L. (2002). Infant sensitivity to distributional information can affect phonetic discrimination. Cognition, 82(3), B101-B111] found that infants change their speech sound categories as a function of the distributional properties of the input. For such a distributional learning mechanism to be functional, however, it is essential that the input speech contain distributional cues to support such perceptual learning. To test this, we recorded Japanese and English mothers teaching words to their infants. Acoustic analyses revealed language-specific differences in the distributions of the cues used by mothers (or cues present in the input) to distinguish the vowels. The robust availability of these cues in maternal speech adds support to the hypothesis that distributional learning is an important mechanism whereby infants establish native language phonetic categories.

Perception of Vowel Length by Japanese- and English-Learning Infants.

This study investigated vowel length discrimination in infants from 2 language backgrounds, Japanese and English, in which vowel length is either phonemic or nonphonemic. Experiment 1 revealed that English 18-month-olds discriminate short and long vowels although vowel length is not phonemically contrastive in English. Experiments 2 and 3 revealed that Japanese 18-month-olds also discriminate the pairs but in an asymmetric manner: They detected only the change from long to short vowel, but not the change in the opposite direction, although English infants in Experiment 1 detected the change in both directions. Experiment 4 tested Japanese 10-month-olds and revealed a symmetric pattern of discrimination similar to that of English 18-month-olds. Experiment 5 revealed that native adult Japanese speakers, unlike Japanese 18-month-old infants who are presumably still developing phonological perception, ultimately acquire a symmetrical discrimination pattern for the vowel contrasts. Taken together, our findings suggest that English 18-month-olds and Japanese 10-month-olds perceive vowel length using simple acoustic?phonetic cues, whereas Japanese 18-month-olds perceive it under the influence of the emerging native phonology, which leads to a transient asymmetric pattern in perception.

Now you hear it, now you don't: Vowel devoicing in Japanese infant-directed speech

In this work, we examine a context in which a conflict arises between two roles that infant-directed speech (IDS) plays: making language structure salient and modeling the adult form of a language. Vowel devoicing in fluent adult Japanese creates violations of the canonical Japanese consonant-vowel word structure pattern by systematically devoicing particular vowels, yielding surface consonant clusters. We measured vowel devoicing rates in a corpus of infant- and adult-directed Japanese speech, for both read and spontaneous speech, and found that the mothers in our study preserve the fluent adult form of the language and mask underlying phonological structure by devoicing vowels in infant-directed speech at virtually the same rates as those for adult-directed speech. The results highlight the complex interrelationships among the modifications to adult speech that comprise infant-directed speech, and that form the input from which infants begin to build the eventual mature form of their native language.

Reconstruing U-Shaped Functions.

It is refreshing to read an issue devoted entirely to U-shaped developmental functions. These functions, and their N-shaped cousins, have intrigued developmental psychologists for decades because they provide a compelling demonstration that development does not always entail a monotonic increase across age in a single underlying ability. Instead, the causes of development are much more complex. Indeed, well-documented U-shaped developmental functions have often led to a re-evaluation of theory and/or a questioning of underlying assumptions. Some U-shaped developmental functions have become so well known as to represent classics in our field. It is doubtful that there is a developmental psychology textbook that doesn’t include coverage of the U-shaped developmental functions in auditory localization, in infant stepping, in a perceptual preference for human faces, or in use of the irregular past tense. It has been suggested that a classic interpretation of this type of finding is that there is a temporary loss or regression in a particular competency which then re-emerges at a later point in development. We would argue, however, that the number of developmentalists who offer such an explanation today is close or equal to zero. Instead, heuristically quite valuable explanations have been offered. For example, in accounting for the U-shaped developmental function in preference for human faces, Morton and Johnson (1991) posited an instinct-like preference for human faces in newborns which is engaged only when face-like stimuli move in the peripheral visual field. This biologically based orienting bias, which they called CONSPEC, gives infants enough experience with human faces to facilitate the emergence by 3 to 4 months of a new mechanism, CONLERN, that enables preferential looking at human faces presented foveally, and supports further learning about particular faces. Morton and Johnson argued that the reason a preference is not evident for either peripherally or foveally JOURNAL OF COGNITION AND DEVELOPMENT, 5(1), 147–151 Copyright

Inferable Centers, Centering Transitions, and the Notion of Coherence

A centering analysis of the corpus of Japanese e-mail that is examined in this article relies heavily on the inclusion of inferable centers. However, utilizing this type of center results in a high level of indeterminacy in labeling transitions and thus in characterizing the coherence of the corpus. The difficulty lies in the requirement of identity of discourse entities in the definitions of transition states. Lexical cohesion is proposed as a well-defined notion to replace the intuitions captured by the use of inferable centers. Two new transitions, based on lexical relatedness instead of identity, supplement the standard definitions and more adequately characterize coherence in this corpus. Implications and extensions of the proposal are discussed.

Age-related changes in sensitivity to native phonotactics in Japanese infants

Japanese infants at the ages of 6, 12, and 18 months were tested on their ability to discriminate three nonsense words with different phonotactic status: canonical keetsu, noncanonical but possible keets, and noncanonical and impossible keet. The results showed that 12 and 18 months olds discriminate the keets/keetsu pair, but infants in all age groups fail to discriminate the keets/keet pair. Taken together with the findings in our previous study [Kajikawa et al., J. Acoust. Soc. Am. 120(4), 2278-2284 (2006)], these results suggest that Japanese infants develop the perceptual sensitivity for native phonotactics after 6 months of age, and that this sensitivity is limited to canonical patterns at this early developmental stage.

Infants’ Discrimination of Consonants: Interplay Between Word Position and Acoustic Saliency

ABSTRACT Research has shown that young infants use contrasting acoustic information to distinguish consonants. This has been used to argue that by 12 months, infants have homed in on their native language sound categories. However, this ability seems to be positionally constrained, with contrasts at the beginning of words (onsets) discriminated earlier. This study explores whether English-learning 12- and 20-month-olds discriminate coda consonants in word-final and word-medial positions. The 12-month-old group successfully discriminated place of articulation contrasts for voiced stops in word-final position, though not voiceless stops in either position, while the older infants discriminated place of articulation contrasts for both voiced and voiceless stops in both positions. This indicates that voiced stops may be more acoustically salient than voiceless, and that position influences discrimination. Our findings support the claim that infants build speech sound categories starting with more salient contrasts in strong positions, which expand to other positions over the course of development.

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.

The phonetic rhythm/syntax headedness connection: Evidence from Tagalog

Ramus, Nespor, and Mehler [Cognition (1999)] show that the rhythm of a language (broadly: stress‐ versus syllable‐ versus mora‐timing) results from the proportion of vocalic material in an utterance (%V) and the standard deviation of consonantal intervals (delta‐C). Based on 14 languages, Shukla, Nespor, and Mehler [submitted] further argue that rhythm is correlated with syntactic headedness: low %V is correlated with head‐first languages (e.g., English); high %V is correlated with head‐final languages (e.g., Japanese). Together, these proposals have important implications for language acquisition: infants can discriminate across rhythm classes [Nazzi, Bertoncini, and Mehler, J. Exp. Psych: Human Perception and Performance (1998)]. If rhythm, as defined by %V and delta‐C, can predict headedness, then infants can potentially use rhythm information to bootstrap into their languages syntactic structure. This paper reports on a study analyzing rhythm in a language not yet considered: Tagalog. Results support the Shukla et al. proposal in an interesting way: based on its %V and delta‐C, Tagalog falls between head‐first and head‐last languages, slighty closer to the head‐first group. This placement correlates well with the fact that, although Tagalog is said to be primarily head‐first syntactically, head‐last phrases are permitted and common in the language.

Vowel devoicing in Japanese infant‐ and adult‐directed speech

It is well known that parents make systematic changes in the way they speak to infants; they use higher pitch overall, more pronounced pitch contours, more extreme point vowels, and simplified morphology and syntax (Andruski and Kuhl, 1996; Fernald et al., 1989). Yet, they also preserve information crucial to the infants ability to acquire the phonology of the native language (e.g., phonemic length information, Werker et al., 2006). The question examined in this paper is whether information other than phonemic segmental information is also preserved, namely, information concerning the phonological process of vowel devoicing. Devoicing of high vowels between voiceless consonants and word‐finally after a voiceless consonant is a regular and well‐attested phonological process in Japanese (Shibatani, 1990). A corpus of speech by Japanese mothers addressed to their infants and addressed to another adult was examined, and the degree and frequency with which they apply vowel devoicing in each type of speech was ...