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WORD LEARNING

WORD LEARNING. A chicken-and-egg problem. You can't learn the language until you know the words BUT You can't segment out the words in the speech input until you know what they are. How could a baby solve the dilemma?. Aslin, Newport & Saffran (1996, 1998)

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WORD LEARNING

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  1. WORD LEARNING

  2. A chicken-and-egg problem • You can't learn the language until you know the words BUT • You can't segment out the words in the speech input until you know what they are

  3. How could a baby solve the dilemma? • Aslin, Newport & Saffran (1996, 1998) • Babies use the pattern of sounds within words to distinguish the ends of words • In Aslyn’s words, babies "pay attention to sounds that cohere within words, compared to the less predictive sounds that change as they span a word boundary.” • When that pattern breaks, the baby understands that a new word is about to start.

  4. How could a baby solve the dilemma? • Part of a word [kn]… • … dle • … cer • … vass • … teen • … cel • … did [kn] • Whole word [kn] • … walk • … talk • … play • … cry • … hit • … eat • … think • ……………..

  5. Transitional Probability (TP) What is the probability that X will be followed by _ ? X A TP(XA) = 1.0 A TP(XA) = 1/3 TP(XB) = 1/3 TP(XC) = 1/3 X B C

  6. Saffran, Aslin & Newport 1996 • Fact: infants often listen longer to novel sounds rather than boring ones • Experiment: infants exposed 7- to 8-month-old infants to a nonsense language for two minute • Question: will infant learn the regularities of the nonsense language?

  7. Saffran, Aslin & Newport 1996 • Nonsense language based on 12 different syllables • Has four tri-syllabic words: word = s1-s2-s3 • pabiku • tibudo • golatu • daropi • Presented as a string of nonsense syllables with no pauses indicating word endings pabikutibudogolatudaropitibudodaropipabiku…

  8. Saffran, Aslin & Newport 1996 • Transitional Probabilities (TP) of the nonsense language • TP of between within-word syllables (i.e. s1-s2 or s2-s3): 1.0 • TP of between between-word syllables: 1/3 (s3-s1, each initial syllable of a word can follow other 3 words of the language, i.e. other 3 syllables)

  9. Saffran, Aslin & Newport 1996 • Testing phase • 4 items in total • 2 of the 'words' from familiarisation, e.g. pabiku & tibudo • 2 ‘partwords’, e.g. tudaro & pigola

  10. Saffran, Aslin & Newport 1996 • Results (n=30) Mean Listening times (seconds) Words part-words Matched-pairs t test 6.78 7.36 t(29) = 2.1, P < 0.05

  11. Saffran, Aslin & Newport 1996 • Interpretation Infants can distinguish between words and part-words after two minutes of exposure • Infants are sensitive distributional properties of the language

  12. Learning names for objects Stager & Werker, 1997

  13. A Straightforward Learning Scenario: • By 1 year of age children know all phonemes in their language • They realize that different objects must have different names (where the difference can be as small as one phoneme) • If so we expect them to have no problem learning word names, including minimal pairs of words (e.g. bear – pear, big – pig)

  14. Stager & Werker 1997 • Novel objects • Novel names: ‘bih’, ‘dih’, ‘lif’, ‘neem’

  15. Stager & Werker 1997: Switch task • Word pairs: ‘bih’ vs. ‘dih’ ‘lif’ vs. ‘neem’

  16. Word learning results • Exp 2 vs 4

  17. Paradox! • 14-month olds fail on minimal pairs of words • But they do know minimal pairs of sounds (as shown in the task that does not require word-learning) • They do know the sounds but they fail to use the detail needed for minimal pairs to store words in memory

  18. Resource Limitation Hypothesis • Stager & Werker (1997) • The complex nature of word learning limits use of the available phonetic information. For a novice word learner, forging a link between a label and an object is a computationally demanding task. • Thus, the resources available for attending to the fine phonetic detail of the word are limited.

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