LIN4151 Language Acquisition

Winter 2006Linguistics, University of Ottawa

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)

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.

How could a baby solve the dilemma?

Part of a word

[kn]… … dle … cer … vass … teen … cel … did

Whole word

[kn] … walk … talk … play … cry … hit … eat … think ……………..

[kn]

Transitional Probability (TP)

TP(XA) = 1.0

What is the probability that X will be followed by _ ?

X A

X

A

B

C

TP(XA) = 1/3TP(XB) = 1/3TP(XC) = 1/3

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?

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…

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)

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

Saffran, Aslin & Newport 1996

Results (n=30)

Mean Listening times (seconds)Words part-words Matched-pairs t test6.78 7.36 t(29) = 2.1, P <

0.05

Saffran, Aslin & Newport 1996

InterpretationInfants can distinguish between words and part-words after two minutes of exposure

Infants are sensitive distributional properties of the language

Learning names for objects

Stager & Werker, 1997

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)

Stager & Werker 1997

Novel objects Novel names: ‘bih’, ‘dih’, ‘lif’, ‘neem’

Stager & Werker 1997: Switch task

Word pairs:‘bih’ vs. ‘dih’ ‘lif’ vs. ‘neem’

Word learning results

Exp 2 vs 4

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

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.

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)

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

Fennell & Werker 2003

Fennell & Werker 2003

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