Baby steps in perceiving articulatory foundations ofphonological contrasts: Developmental changes ininfants' perception of cross-modal AV congruency for
native and nonnative consonants
講師：Catherine Best (University of Western Sydney)
日時：2015 年 7 月 14 日（火）16:00-17:30
会場：慶應義塾大学三田キャンパス東館８階東館ホール
参加費無料 申込不要 （使用言語：英語）＊発表要旨は裏面をご覧下さい＊

共催：慶應義塾大学言語文化研究所
慶應義塾大学赤ちゃんラボ
後援： 福澤諭吉記念慶應義塾学事振興基金<お問い合わせ先>〒108-8345 港区三田 2-15-45 慶應義塾大学言語文化研究所
電話：03-5427-1595 (事務室直通) メール: genbu@icl.keio.ac.jp
http://www.icl.keio.ac.jp

Abstract
Whether the perceptual primitives that perceivers use to recognize phonologicaldistinctions include articulatory information or, as widely assumed, only acoustic
information remains an important topic of debate. The answer is central tounderstanding infants’ early steps toward acquisition of their native phonology.
Compatible with the premise that perceivers detect articulatory information in speech,
adults’ perception of acoustic speech is systematically influenced by visible speech
movements: a synchronously-presented phonetically-congruent talking face enhances
intelligibility of speech in noise, whereas a phonetically-incongruent face can produce“misperception” of the audio token’s place of articulation (McGurk effect). Similar
results have been found in young infants. But bimodal audio-visual (AV) studies alone
cannot pinpoint whether perceivers detect amodal articulatory correspondences
between audio and video signals, or instead rely on learned AV associations between
specific audio speech categories and the co-occurring face motions they haveexperienced with those sounds. Resolving this issue requires examination of: 1)
intermodal recognition (cross-modal “transfer”) of the common information between
audio-only (A) and video-only (V) tokens of a given speech target; and of 2)
developmental changes in recognition of experienced (native) versus non-experienced(nonnative) speech contrasts. The only prior such study tested English vs. Spanish
infants’ detection of A→V congruence in a visible contrast used in English but not
Spanish: /b/-/v/. Both groups succeeded at 4 months but only English infants did so at
11 months (Pons, Lewkowicz, Sebastián-Gallés & Soto-Faraco, 2009). The 4-monthresults refute the hypothesis that perception of intermodal congruence rests on learned
A-V associations. However, because both stimuli were labials (same articulator: LIPS)
we can’t tell whether they detected AV congruence based on articulator-distinct orother information (e.g., phonetic features; cross-modal psychophysical properties).
Moreover, as Spanish 11-month-olds fail to discriminate audio-only /b/-/v/, their lack ofdifferential response to the silent /b/ vs. /v/ videos after being habituated to audio /b/ or/v/ tells us nothing about their ability to detect intermodal congruencies. Therefore, we
designed a series of studies on 4- and 11-month-old infants’ detection of intermodal
A→V congruency for visibly-distinct between-articulator contrasts (LIPS-TONGUETIP) in native and two types of nonnative consonants. We conducted three experiments
to assess sensitivity to intermodal A→V congruence in Australian English-learning
infants of 4 months (n = 20/expt) and 11 months (n = 20/expt): English stops /pa/-/ta/(Expt 1); Tigrinya ejectives /p’a/-/t’a/ (Expt 2); !Xóõ bilabial vs. dental clicks /ʘa/-/ǀa/(Expt 3). In a separate study we confirmed that both ages can discriminate audio-only
tokens of these clicks. We found that 4-month-olds showed a fixation preference for
A→V articulator congruency in both the English and Tigrinya contrasts, but
11-month-olds only preferred A→V congruency for English, reversing to a novelty
preference for the Tigrinya ejectives. In striking contrast, the 4-month-olds showed anA→V incongruency preference for the !Xóõ clicks, while the 11-month-olds failed todetect any A→V congruency relationship. We propose that both 4- and 11-month-olds
recognize the Tigrinya ejectives as speech articulations, but only the older group
recognize that they are deviant from English. In contrast, 4-month-olds alreadyrecognize !Xóõ clicks as deviant from English, while 11-month-olds instead treat themas nonspeech, like adults. We will discuss the implications of these findings for theories
of native-language perceptual attunement and phonological development.