Agenda Pomona College LCS 11: Cognitive Science ֠ Results of evaluations ֠ Perception in language acquisition Language acquisition 2 ֠ Prosody in womb ֠ Categorical percetion ֠ Loss of perceptual ability Jesse A. Harris ֠ Effects of general context April 1, 2013 Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 1 Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 2 Perceptual abilities Knowledge of language – sound Phones Main question for today What sounds the language uses in its inventory. E.g., English How early do perceptual abilities appear in language uses the voiceless dental stop [t] sound but not, say, bilateral acquisition? fricatives [ B ]. ◮ Attend to rhythmic and language specific properties very Phoneme early, even in the womb! What sounds are distinctive in a language, i.e., can constitute a meaningful distinction. ◮ Sucking rate experiments – very early preference for familiar language (1) a. p at (voiceless) ◮ We’re born to learn any possible language, but we quickly b. b at (voiced) specialize. c. p h at (aspirated) Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 3 Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 4
Knowledge of language – sound Processing prosody in the womb Prosody The contour that overlays speech pattern, including rhythm, DeCasper et al 1994: mothers read a volume, stress, pitch, duration, emphasis, and contrast. Also short nursery rhyme aloud for 4 can convey an expressive dimension of communication. weeks during late pregnancy. Heart (1) a. You’re gonna eat that? rate of the foetus decreased when the familiar rhyme was read as b. You’re gonna eat that! compared to a novel one. ◮ Language learning starts with prosodic – especially Z Yet, not enough information to rhythmic – patterns in the womb! distinguish within language ◮ Foetus develops in amniotic fl uid protected by layers sounds. skin, fat and muscle. Only limited range of sounds pass through (1000Hz; Altmann 1997) http://www.youtube.com/watch?v=_JmA2ClUvUY Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 5 Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 6 Processing prosody out of the womb Complications Newborns able to distinguish prosody of parents’ language from other languages (with signi fi cantly di ff erent prosodic String of pearls model structure). Assume a one-to-one correspondence between acoustic signal and the phonetic category. Listener maps sound onto a string. ◮ 4 day old infants from Coarticulation monolingual French families When a sound takes on the characteristics of another sound ◮ Compated fi ltered French v. due to proximity to it. English speech. ◮ Infants sucked faster when (2) Pronounce the following naturally: Is the ’n’ the same? presented with novel prosody, a. te n indicating that they recognized b. te n th the French prosody as familiar. (3) a. lea n dog b. lea n bacon http://psych.rice.edu/mmtbn/language/sPerception/infantsucking_h.html Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 8
Categorical perception Categorical perception ◮ Despite continuous spectrum, Part 1: Identi fi cation perceive differences as Identify which syllable you categorical. hear from selection of two ◮ Voice onset time: the time or three: shift in perception between a stop and the is abrupt, as you don’t perceive within category begining of voicing (vibration di ff erences. of vocal cord). ◮ Don’t distinguish until Part 2: Discrimination Discriminate between boundary. sounds well at boundary, but poorly within category. Experiment on synthetic ba, da, ga http://www.ling.gu.se/ ∼ anders/KatPer/Applet/index.eng.html Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 9 Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 10 Categorical percetion Universal listeners Conditioned head turn procedure Development of categories ◮ New phoneme randomly introduced ◮ Categorical perception is learned . ◮ Infant is rewarded when they detect the change ◮ Infants are universal listeners – able to distinguish any http://www.youtube.com/watch?v=dAU5CAl1U6M phonetic contrast. ◮ But sensitivity rapidly decreased within fi rst year. Rapid decline in sensitivity Categorical perception in development ◮ Infants 6 –10 mo. able to distinguish two non-native contrasts, e.g., Hindi /t/ and /T/. Ability vanishes after Develop limited sensitivity to phonetic contrasts: perceive irrelevant di ff erences, e.g., /p/ and /p h / as the same phonemic this (unless excessive training). category in English, or /r/ and /l/ in Japanese and Korean. http://www.youtube.com/watch?v=Ew5-xbc1HMk Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 11 Jesse A. Harris: LCS 11: Cognitive Science, Language acquisition 2 12
E ff ects of context Adult listeners depend on contextual knowledge as well 1. Phonemic restoration ◮ Left – decline of http://www4.uwm.edu/APL/players/TI_SPR.html sensitivity to Warren and Warren 1970 presented sentences with Hindi contrasts obscured phones; restoration of the syllable depends on ◮ Right – decline the surrounding context. of sensitivity to Nthlakapmx (7) It was found that the *eel was on the ... contrasts axle • shoe • orange • table • In a nutshell . . . 2. Non-linguistic context Lose perceptual sensitivity when we do not need to maintain it http://www.youtube.com/watch?v=KiuO_Z2_AD4
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