Language Flashcards
What is a phoneme?
The smallest unit of sound in a language that is capable of conveying a distinction in meaning. e.g. bat vs pat
Consonants
Defined by features that affect how the air is blocked and how that interacts with the sound.
- Voicing: when do vocal cords begin to vibrate?
- Place: where is the obstruction being made?
- How is air passed through?
Voicing
Voiced/voiceless phonemes differ by voiced onset time (VOT) the time it takes for your vocal cords to start vibrating
Vowels
Defined by features that affect the shape of the mouth and where the vowel is pronounced
- Tongue position: how big is the space in the mouth?
- Lip posture: where in the mouth are the vowels pronounced?
Langauge differences
Different languages have different phonemes - english has about 40, some polynesian languages have as few as 11
Categorical perception
Consonant phoneme boundaries are perceived categorically. As a result of this categorical perception, native speakers of one language can’t hear the phonemes of other languages very well (unless they happen to be the same)
How are phonemes learned? Developmental trajectory
0-4 months
- infants can discriminate phonetic contrasts in all languages
- Around 3 months, they start to babble (mainly vowels at this point)
4-8 months
- Infants begin to learn the speech sounds of their language
- babbling becomes more speech-like (‘da-da’)
8-12 months
- lose the ability to perceive sound distinctions that are not in their language
- babble sounds appropriate to their language
Phoneme learning is just category learning!
We can therefore test whether we use the same mechanisms and representations to learn phoneme categories as any other kind of category.
is there reason to believe that the distribution of sounds in the input affects what phonemes people learn?
lecture1
Empirical evidence: training study
lecture1
How does phoneme learning link to other aspects of language learning?
- Training studies: teaching adults new phonemes can help them learn words with those phonemes
Results: training adults on a new phoneme contrast improved their ability to learn words with that phoneme contrast - Longitudinal experiments: Infants who are better at hearing phonemes have better vocabularies later on.
6 months: infants trained to hear new phonetic contrast. Measure: trials to criterion=speed of habituation (faster=better learning)
13 months: parents filled out vocabulary list
CDI = communicative development inventory (measure of vocab size)
RESULTS: phoneme learning at 6 months predicts later vocabulary size
The problem of word segmentation
Spaces between words cant be heard
Possible solutions
- Language-specific phonotactic constraints: restrictions on which sequences of sounds are permissible in that language (Which is more likely to be a word in English? Thipe? Ndimi?)
- Language specific prosodic constraints: which stress patterns are common (How should i pronounce this word?)
Problems with phototactics and prosody alone?
- only get you so far - the constraints arent sufficient enough to come up with a very good full segmentation
- for both, you need to something about what things are words before you can use them
Another idea: Transition probabilities
Probably used in conjunction with these other cues
- this is a type of statistical or distributional learning (i.e. it is based on observing the statistical distribution of things)
Probably a word - probably not a word
An empirical test
Can people segment words in an artificial language simply on the basis of transition probabilities?
- test by seeing if they recognise the difference between partial words and non-words
- habituate infants to a long stream of this speech. After they get bored, play either a speech stream containing partial words like ‘daku’ or non words like ‘kupa’
- Infants listened longer (indicating surprise) to the non-words than the partial words
One problem: the partial words and non-words differed not just in transitional probabilities, but also in frequency.
Idea for empirical test
Match for frequency by making a language with words of varying frequency
Results - infants listened longer (indicating surprise) to partial words than the words
Transitional probabilities seem fairly effective! Leads to several questions, though…
- how well does this scale to real language? (i.e. how much of the word segmentation problem do TPs solve?
- what kinds of things can people do this sort of statistical learning over?
How well does this scale? 2 ways to answer this
- experiment with people - use languages that are less artificial
- computational model - take a program that can calculate TPs, give it a corpus of typical data and see how many words it segments correctly
What does TP learning apply to?
- Can we learn them if its not about language?
2. Can we learn them if its not over adjacent units?
lecture 2
lecture 2
lecture2
lecture2
TP summary
TPs are probably very useful for word segmentation
- people (even infants) can track them
- Scales to real language moderately well
- computational algorithms using them segment okay
- not a language-specific skill
How does word segmentation link to other aspects of language learning?
- learning words
- learning lexical categories (e.g. nouns, verbs etc)
- improved efficiency/speed of processing
word segmentation –> word learning
it is easier for people to learn words that they have previously learned how to segment from rapid speech
Why is word learning difficult?
Many possible meanings for every single word. e.g. ‘quidditch’ - weird armour stuff, sitting on a broom, the game he’s playing, being a wizard, suspended in air..
Children do quite well at word learning
The first words generally come in between 8-14 months but there is tremendous individual variability
After the first words there is generally a vocabulary spurt, characterised by faster learning.
This can occur between 14-24 months and depends on child
This continues to accelerate throughout childhood and slowdown in adulthood
Age of acquisition effects
Interestingly, the age at which a word was learned has effects later in life. impacts on: - Speed of lexical retrieval - Lexical decision tasks - word familiarity
Learning words quickly
The fast rate of word learning in later life is probably in part due to people’s capacities for fast mapping: learning the correct referent of a word after only one or two labellings
How do people learn words?
A bias of some sort is necessary to solve the word-learning problem.
Possible biases:
1. Labels are ‘special’ to people (especially infants) in some way
2. it’s not that labels are special; rather people can learn over time about how labels are used