Upload
amie-barton
View
223
Download
0
Embed Size (px)
Citation preview
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
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)
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