1. LIN4151 Language Acquisition Winter 2006 Linguistics, University of Ottawa

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?
[kn]
Part of a word
[kn]…
… dle
… cer
… vass
… teen
… cel
… did
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
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 attentional resources available for attending to the fine phonetic detail of the word are limited.

19. Testing the Resource Limitation Hypothesis
Infants are predicted to do better if the task of sound-meaning association is made easier for them
How?
By using sounds and ocncepts that are familiar to the infant!
Swingley & Aslin (2003)
Fennell & Werker (2003)

20. Swingley & Aslin 2003
Children do not confuse known words with their neighbors, e.g. baby ≠ vaby
Fennell & Werker 2003
In a switch task, children distinguish minimal pairs of familiar words, e.g. ball - doll

21. Fennell & Werker 2003

22. Fennell & Werker 2003

23. Phones vs. Phonemes?
One-year olds know the phones of their language, i.e. which sounds are used and which are not
They still need to learn which sounds are used contrastively in the language…
…and which sounds simply reflect allophonic variation
One-year olds need to learn contrasts