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Lecture 2

PSY315H5 Lecture Notes - Lecture 2: Categorical Perception, University Of Manchester, Eye Tracking

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Craig Chambers

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PSY315 Lecture 2
Phonological Development
Sound systems in language:
- contrastive: capable of conveying contrast relative to other sounds
- contrast: create a difference in meaning if you substitute that sound for another in some particular
- ex. Pill
o p soud, sustitute it for  ad sustitute it for a differet eaig ill
o p ad  are differet souds of the Eglish laguage, eause the are otrastie
- ex. Might and night
o they sound similar
but express different meanings
 ad  are otrastie in English
- different ways of pronouncing the sound /k/ in English
o versions of the same sound
measuring the development of speech abilities:
- perception of sounds: how they process sounds
- production of sounds: how they produce these sounds
tend to see the emergence of perception abilities before they are able to produce those in their own
Learning the phonetic inventory:
- What is the initial state?
o One possibility
All just undifferentiated noise
Brain is categorizing them equally
o Maybe you start to differentiate between quiet and noisy sounds
Set of progressively finder distinctions that are made over the
course of development
How is this going to be tested?
1. High-Amplitude Sucking (HAS)
a. Pacifier hooked up to electrode
b. Pacifier in babies mouth
c. Babies suck on pacifier at a certain rate
d. As child gets bored, sucking rate is decreasing
e. Indirect measure of interest in the child
f. Combine with paradigm where stimulus is repeated over again (what should happen: sucking
rate dereases eause its orig ad the pla hat is pereied  ifat as a e soud
i. If the pereie it as differet the sukig rate should irease its e, iterestig
ii. If the dot the othig should happe
2. Conditioned Head-Turn paradigm (more common)
a. Association where child learns new sounds and some kind of visual stimulus
b. Habituation paradigm
i. Ability to look at behaviour in regard to boring stimuli with new stimuli
looking at where two sounds are perceived as different
Back to the questio: Whats the iitial state for detetig otrasts?
- most sounds, infants perceive differences among the sound from the starting point
- starting point: children pre-packaged to hear lots of different speech sounds
o include speeh souds that their parets dot pereie as eig differet
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PSY315 Lecture 2
- ifats oe as pakaged uiersal listeers
o reduig the otrast oue ee eposed to
o sensitized to the language you are going to use
When does this happen?
- over the course of the first year
- initially, high ability to make discrimination between sounds
o continues to go down
- doest atter hat souds the are
- by the end of the first year, narrowed into the contrasts that are relative for your language
- sounds not contrastive to your language: non-native sounds
- not true of all speech sounds
A puzzle
- if the haet started to zoo i o the set of speifi speeh souds, ho a the hae this ailit to
differentiate their language from other languages?
o Rhythmic, intonation characteristics of the language
Allows them to recognize their language
- Categorical perception:
o There are stimuli that could belong to two different categories, how is it that the perceptual
system categorizes which category perceptual stimuli belong to?
o For speech sounds
Differences between speech sounds are a matter of degree
Not qualitatively different, they are quantitatively different
o Ex. How high is the tongue? Is it more to the roof of the mouth, bottom
of the mouth, more to the back?
o Doest see to haraterize ho other tpes of pereptio ork
Example 1: colour wavelength
- continuous perception
o for each wavelength, we are able to tell
- Pereptio of speeh doest ork the sae as the pereptio of olour
o Systematically keep hearing speech sounds that belong to a particular category
At log oie oset soud, goig to hear a pa soud, at short goig to hear a a
- in-between values:
o should soud ore like a suessiel
o ith eah shrik should soud ore like a as oppose to pa
Is this what happened?
o People ehae relatiel osistetl i hearig a pa util the hit soe
over cross-over point when suddenly they switch over
o Steep gradient in the middle:
Referred to as categorical perception
People behave uniformly on either side of the boundary
o Regardless of the fact that they are playing
increasing voice onset sounds
Extreme crossover: have ambiguity
Dot see the differee etee the util e get to this
crossover point
o Categorical Perception of speech
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