PSYCH 2220Perception

Lecture 11

Do we need to LEARN to see?

KEYWORDS for lecture 9

"do we need to learn to see?", empiricists (yes), nativists (no),

innate visual behaviours, dung beetle, chimpanzees and snakes, ducklings and hawks, Molyneux's question ("if a man is given his sight as an adult, could he distinguish a sphere and a cube?"), two patients described, babies, mixed up faces, visual cliff, contrast sensitive function for infants, preferential looking, adaptation (remember that Dalmatian!), inverting prisms, hens show no adaptation, horizontal or vertical rearing

EMPIRICIST(all knowledge comes from experience)

NATIVIST(knowledge is ‘a priori’; you are born with it)

1 animal behaviour

Molyneux’s question:

“could a man born blind distinguish a sphere and a cube by sight alone?”

2 blind people recovering sight

S.B could see with minimal experience

H.D. never could see very well.

3 child development, Fant’z Experiment

4 adaptation

5 controlled rearing

walks activelycarried passively

Animal behavour

Blind people recovering their sight

Babies’ visual development

Adaptation experiments

Controlled rearing experiments

EVIDENCE

……………………. Nativist

… Empiricist & nativist

…………. Empiricist & nativist

…………… Empiricist

……….. Empiricist

INTRODUCTION TO HEARING

pinna(external ear)

malleusincusstapes

little bones

oval windowtympanic membrane (ear drum)

leverage= 1.3 x

this section coiled upin the actual ear (cochlea)

(ossicles)}

areadecrease17 x

}

OUTER EAR MIDDLEEAR

INNER EAR

helicotrema

basilar membrane

top tube

middle tube

bottom tube

tectorial membrane

hair cells

vibrations pass down the top tube to theend (the HELICOTREMA) and thenback down the bottom tube.

helicotremaoval window

vibrates most tohigh frequencies(around 10 kHz)

vibrates most tomiddlefrequencies(around 1 kHz)

vibrates most tolow frequencies(down to around27 Hz)

hairs

hair cell

nucleus

fibre of 8th nerve (auditory nerve)

ACTION POTENTIALS TO BRAIN

Auditory system 13 - 5

10 100 1000 10,000Frequency (Hz)

(high)(low)

020406080

100(loudest)

(quietest)

sound levelin decibels(dB)

can hear

can't hear

this line shows thequietest sounds youcan hear. At soundpressure levels belowthis line you can't hearthe sound.

10 100 1000 10,000Frequency (Hz)

(high)(low)

020406080

100(loudest)

(quietest)

sound levelin decibels(dB)

*

*

*

All points on this curve have the same perceived loudness as the standard (*)

All points on this curve have the same perceived loudness as the standard (*)

All points on this curve have the same perceived loudness as the standard (*)

EQUAL LOUDNESS CURVES

Place theory1 - Travelling wave; stiffness varies2 - one place most active for a given frequency3 - tonotopic code; coded as place

Periodicity theory1 - sound coded as pattern

Hearing thresholdsEqual loudnessMaskingThe case of the missing fundamental

harmonicspitchtimbre

Training a goldfish...

Evidence against place-- Missing fundamental-- which can be masked -- some animals have no basilar membrane

Evidence against periodicity-- cells can’t fire fast enough-- diplacusis

Evidence for place-- physiology

Evidence for periodicity-- multiple cells could do it-- phase locking of cells

Place theorysound coded as place

Periodicity theorysound coded as pattern

Duplicitybelow 1kHz, coded by periodicityabove 1 kHz, coded by place

Auditory localization

1 inter-aural time of arrival differences-- circle of confusion

2 inter-aural intensity differences3 pinnae (up/down front/back etc..)4 head movements

hairs

hair cell

nucleus

fibre of 8th nerve (auditory nerve)

ACTION POTENTIALS TO BRAIN

Auditory system 13 - 5

Auditory cortex

Auditory thalamus

Superior colliculus

Inferior colliculus

cochlea

Cochlear nucleus

Superior olive

The AuditorySystem

The AuditorySystem(cortical route)

Cochlear nucleus

Inferior colliculus

thalamus

cortex

The AuditorySystem(sub-cortical route)

Cochlear nucleus

Superior olive

Inferior colliculus

Superior colliculus

The AuditorySystem

front

back

left right

The SuperiorColliculus

a a

a

b

b

c

c

d

d

f

g

LOCALIZATION OF FUNCTION IN THE CORTEX

Phrenology

Visual cortex.

Motor cortexSomatosensory cortex

Auditory cortex

Olfactory cortex

FRONT

• Stimulation• recording• lesions• anatomy

PARIETAL CORTEX (the"WHERE" system)...

INFEROTEMPORAL CORTEX(the "WHAT" system).

FRONTALCORTEX (involvedin personality)

PARIETAL CORTEX (the"WHERE" system)...

INFEROTEMPORAL CORTEX(the "WHAT" system).

FRONTALCORTEX (involvedin personality)

Phineas Gage

BROCA'S AREA(speech production)

WERNICKE'S AREA(speech comprehension)

corpuscallosum

from above from front

THECORPUSCALLOSUM

RIGHT

FIELDVISUAL

LEFT

FIELDVISUAL

LEFT RIGHTBRAIN BRAIN

left eye sees right eye sees

left hand touches

right handtouches

“SPLIT BRAIN”