Categorical Perception

Question 1

What is categorical perception?

Answer 1

Perception of different sensory phenomena as being qualitatively or categorically different

Question 2

What is continuous perception?

Answer 2

The perception of different sensory phenomena as being located on a smooth continuum

Question 3

When does categorical perception occur?

Answer 3

When a change in some variable along a continuum is not perceived as gradual, but as instances of discrete categories

Question 4

Are within category differences important?

Answer 4

No, they are compressed

differences between categories are more important

Question 5

What does categorical perception occur for?

Answer 5

Consonant continua - voice onset time, place of articulation

less evident for vowel continua

Question 6

Why are stop consonants categorical?

Answer 6

Because of their place of articulation: either labial, alveolar or velar
and their manner in terms of articulation: voiced or voiceless

Question 7

What is a voiced articulation?

Answer 7

No clear interruption of voicing

Question 8

What is a voiceless articulation?

Answer 8

Involves a clear interruption of voicing

Question 9

What does the place of articulation affect?

Answer 9

The transition of the formant

Question 10

What is a formant?

Answer 10

Band of frequency which determines the phonetic quality of a vowel

Question 11

What makes a sound B or P?

Answer 11

The duration of the silence
5ms - B
40ms - P

Question 12

What has to occur for something to be defined categorically?

Answer 12

sharp phoneme boundary
discrimination peak at phoneme boundary
discrimination predicted from identification

Question 13

What is a sharp phoneme boundary?

Answer 13

The point at which we hear one category to the next has to be sudden and abrupt - meet a threshold, then all switch to hearing another one

Question 14

What is a discrimination peak at phoneme boundary?

Answer 14

Where things that vary by a small amount should sound very different - across a category, variation should be perceived as very different

Question 15

What is discrimination predicted from identification?

Answer 15

They only sound different if identified as different phoneme

Question 16

Categorical perception of the Ba/Da continuum

Answer 16

B and D are two voiced stops which differ by their place of articulation:
b is bilabial
d is alveolar
affects the slope of the second formant

Question 17

Experimental evidence of CP

Answer 17

1. Set up a continuum of sounds between two categories

2. Run an identification experiment

Question 18

How do you synthesise sound between two categories?

Answer 18

By gradually changing the shape of the formant from upwards to downwards

Question 19

What will an identification experiment show?

Answer 19

Everyone will hear Ba till you reach phoneme boundary then everyone starts hearing Da

Question 20

What determines how much phonemic boundaries can vary by?

Answer 20

Individual differences and the language people have acquired throughout development - sometimes lead to people arguing about what they have heard

Question 21

Are we good at discriminating between ordinary continua?

Answer 21

We are good at discriminating between frequency, loudness, brightness etc but not very good at labelling these differences

Question 22

Why will there be a discrimination peak?

Answer 22

As one will be on one side on phonemic boundary and one will be on the other side

Question 23

Are we good at discriminating between categorical perception?

Answer 23

No - we are better at labelling than discriminating

Question 24

What does Liberman believe?

Answer 24

Categorical perception is an indicator of a special speech mode of perception that is distinctively human - phoneme is a result of human mapping auditory signal to articulatory positions - speech signal we hear is continuous but produce discreetly

Question 25

Is categorical perception limited to speech?

Answer 25

If it is true that it is humans only, it should be but no also shown by musical intervals

Question 26

Is speech categorical perception unique to humans?

Answer 26

Identification - no, chinchillas and quails show the same VOT boundary as humans for the da, ta continuum - can be trained to respond differently Discrimination - macaques show discrimination peaks at human VOT and place of articulation boundaries - suggests human speech exploits low level discontinuities in the way that vertebrate auditory systems represent sound

Question 27

Is it innate?

Answer 27

Infants are born with the ability to make speech discriminations.. that they can't make animals make many of thee adults and one year old infants lose the ability to make distinctions that their language doesn't use this is why it is difficult to acquire new languages

Question 28

Why is it hard to acquire new languages?

Answer 28

Because adults lose the ability to make distinctions that their language doesn't use - hard to perceive categories so hard to segment words into phonemes, different phonemes sound the same, so hard to articulate

Question 29

How is CP acquired?

Answer 29

Reduction of perceptual sensitivity within native phoneme boundaries sensitivity can be re-acquired with intensive training

Question 30

What is a phone/phonetic sound?

Answer 30

A particular sound used by any language. e.g. the sound r or the sound l 2 different sounds

Question 31

What is phoneme/phonemic sound?

Answer 31

A sound used in contrast to another in a particular language e.g. the category r as distinct from i - these are two phonemes in English but in Japanese they sound similar to listeners so as a consequence they don't form 2 different phonemes

Question 32

What are minimal pairs?

Answer 32

Phonemes in a particular language are defined by minimal pairs e.g. in English, lice and rice have a different meaning, because they contain different phonemes which constitute a minimal pair there is no such thing as a minimal pair in Japan, so they have a single phoneme r

Question 33

What does each language have?

Answer 33

Its own set of phonemic categories English distinguishes r from l but Japan doesn't Tamil distinguishes from a dental t1 from an alveolar t2 but english doesn't

Question 34

Effect of experience on perception: what is the difference between ra/la?

Answer 34

The slope of the third formant ra - up la - down

Question 35

If you run an experiment where you vary the slope of the third formant, what happens?

Answer 35

English listeners - perceive ra then suddenly la, there will be a discrimination peak in pairs which vary by a small amount of slope Japan - Ra throughout, no peak

Question 36

Iverson - synthetic stimuli

Answer 36

Listeners asked to identify and rate stimuli American - everything to the left of phonetic boundary was heard as R. Things are separated but clustered at either side because they sound more similar Japan - most perceive as R, only one as W German - boundaries have shifted from Americans, not as clearly organised as Americans, some are to the left all dependent on language exposed to as a child

Question 37

What is the McGurk effect?

Answer 37

Speech perception is multimodal: integration of visual and auditory cues Articulatory gestures influence auditory perception - brain is being articulated - top down influences