Perception and Cognition Flashcards
what is the visual pathway
primary visual cortex in one hemisphere receives…
eye - LGN - primary visual cortex primary visual cortex in one hemisphere receives only 1/2 visual field from contra-lateral (opposite) side from both eyes
explain the receptive field of the ganglion cells
has two components
excitatory centre
inhibitory surround
V1 primary visual cortex - how is it arranged
circular receptive fields from LGN combined into an elongated V1 still with an excitatory centre and inhibitory surround
simple cells - Hubel and Wiesel
primary visual cortex V1 cells
selective for position on t=retina
orientation of edge / bar
size or width or bar
hierarchical processing in V1
simple cells combine to form the complex cell again with excitatory centre and inhibitory surround
complex cells are selective for
rough position on the retina
orientation of edge / bar
size or width of bar
movement within receptive field
hypercomplex cells
how formed and additionally what are they selective for
complex cells combining and again same structure
length of edge or bar
needs to sop at one or both ends
what does different types of receptive fields in V1 lead to
different orientation and spatial scale
leads to edges
the receptors are all orientated differently across the visual field so can do edges
organization of the primary visual cortex
cortex mapped
one are processes contours on one region of retina
cells analysing one orientation lie in same column
damage to V1 leads to blindness (local field defect)
what is Gestalt psychology about
the whole is more than the sum of the parts
grouping principles of perceptual organization: similarity - in luminance, shape, colour
grouping principles in gestalt psychology
similarity proximity closure good continuation common fate law of closure maximum likelihodd principle parts of the image are seen as belonging together. these parts are likely to arise from the same object
secondary visual cortex
V2
von der heydt, peterhans
v2 cells are selective for edges defined by good continuity and closure
v2 damge impairs grouping by some principles
good continuity, closure, similarity (colour
gestalt principles - figure-ground
area bounded by contour is seen as separate object
contours seen as belonging to one object at a time
problems in recognition
an p=object changes with distance position perspective view orientation lighting occlusion of parts
object agnosia
failure to recognise objects
no loss of intelligence
no simple visual impairment
may draw object ok but not recognize drawing if later presented back to him
can see edges but cannot put them together
at first was thought to be a case of dementia coupled with poor vision - clearly fine vision and patient did not have dementia
brain scan found two localised lesions
two types of edge/bar detectors (types of edges they detect)
fine and coarse
Marr’s model of recognition
analyse image with range of edge filters
use gestalt grouping principles - eg continuity finds outline
segment outline at nearest concavities
define arrangement of part (cylinders)
- start with biggest cylinder (principle axis)
-work though progressively smaller cylinders
match descriptions f parts to 3D models in memory
mar’s model of recognition, model predicts..
problem…
visibility of principle axis important
different orientations equally easy to recognise
problem - many objects gard to recognise if upside down or rotated
Biederman ‘recognition by components’
detect arrangement of edges parallel co-linear co-terminating such arrangements do not alter with view determine geon type determine arrangement of geons match geon description to memory
geons
part of biederman’s recognition by components
36
axis straight or curved?
cross section type (symmetric, smooth, angular)?
when arranged size, orientation to each other?
problem with biederman
does not differentiate objects within class does not use surface pattern
processing of form - where in the brain
pattern processing in temporal cortex cell selectivity code shape and colour and texture respond to all objects with these properties generalise across position orientation and size specific organised in columns =
summary of how we perceive what we see
v1 edges - v2 contours - v4 simple features - elaborate features in the temporal cortex
object coding
one cell not coding object concept (eg isn’t a cell for a pineapple)
object identity coded by large arrays of cells
vocabulary of around 500 properties to code many objects
what does a lesion to the temporal cortex do
disrupts pattern discrimination and object recognition
produces object agnosia
prosopagnosia
symptoms
interpretation
failure to recognise individual faces
may recognise individuals bu theor clothes, voice
may recognise other objevt
faces processed by a specialised brain system?
within object class discrimination defective? - patient may not recognize different cars, birds
patient WJ
WJ could remember sheep but not human faces
object agnosia patient
patient CK could see faces but not vegetables
double dissociation - separate impairments in recognition of faces and objects
fusiform face area
right fusiform area - faces > objects
faces but not other objects of expertise (eg cars) activate area
extrastriate body area
right occipitotemporal area: bodies > objects
where is the extrastriate body area
mid temporal
where is the fusiform face area
parahuppocampal place area
hierarchical models of processing
- hubel and wiessel’s findings in the visual cortex
- simple-> complex-> hypercomplex - selfridge’s pandemonium model. feature demons -> cognitive demons - > deciiosn demon
- grandmother cells
hierarchical processing what are grandmother cells
problems?
specificity - respond to one object only
generalisation - respond to many instances
problems
not enough cells in the brain
but eery 1mm3 contains 1 million cells and most people recognise 20,000 words
unlikely to ever find them
monkey fMRI patch responsive to faces
test single cells in fMRI patch
16 faces, fruits, bodies, gadget, hands, scrambles
99% of cells selective for faces
summary of face processing in temporal cortex
V1 and V2 features -> temporal cortex elaborate feature -> STS faces
what face processing happens in the temporal cortex
cell populations selective for sight of face
generalize over size, position, orientation, lighting
most selective for view: so Marrs’ model wrong
some 5% of cells show sensitivyt to identity
other cells selective for familir objects
visual cues for facial recognition
features
internal (eyes, mouth, nose)
external - hair
configuration - features have to be in the right place
face familiarity
external features more important for unfamiliar faces
internal faces more important for famous faces
thatcher illusion
features analysed independently
each feature coded relative to gravity
you don’t notice if individual features flipped to right way round when face upside down
facial averageness
faces added together and warped to make a single average face - tends to be smooth and a little blurry\
we find average faces most attractive - probably an evolutionary explanation
effects of caricatures on face naming (famous faces, exaggerate features, can you name them?)
50% caricature can recognise the face almost twice as quickly compared to the original
caricatures exaggerate deviation from average
caricature familiar faces can improve recognition
implies faces coded by differences from average
brain asymmetry in face perception
face split vertically and mirror images formed left and mirror left look more like the target than mirror right
also if shown half male, half female face, the half of the face on the left dictates the answer
face perception is biased so left eye information favoured onto right hemisphrere
what is the perceptual bias in face processing and what is the explanation
judgements of face identity, sex, age, attractiveness are biased to left side of face
explanation
left 1/2 face projects to observers right hemisphere
right hemisphere is specialised for face processing
real life tests in IDs
supermarket check-out workers told to expect fraudulent credit cards and to check photo IDs
despite warnings 50% of false ID cards accepted
eyewitnesses inaccurate in identifying a face
30% errors identifying unfamiliar faces (live or video)
experience/training dos not improve accuracy
police officers = students matching photos to CCTV images
conclusions to draw from face identification
recognition of familiar faces is excellent
yet recognition of unfamiliar faces is very poor
beware eye witness claims
facial expression of emotion - production
cross cultural similarity of expressions and causes
dear and blind children’s expression are normal therefore production of expressions is innate (Darwin)
cultural similarities - Ekman imagine your child died all came up with same facial expression
cultural differences - Asian faster changes in eye region, Jack et al
less negative expression in Japan compared to USA, matsumoto et al
comprehension of facial expression of emotion
universal interpretation of 6 basic emotions (Ekman) - happy, sad, angry, fear, surprise, disgust
does this mean comprehension is innate? or is there a potential role for learning
fear
facial expression similar across species
lab-reared monkeys show no fear of snakes
learn if another monkey seen fearing snakes (mieka and cook)
fear learning is stronger for snakes than flowers
adaptive if there are few or no poisonous snakes
vicarious (social learning) of what fear is
fear expression activate … compared to happiness
activates the amygdala (more scared the face, more amygdala activation)
happy expression inhibit the amygdala
brain imaging for facial expressions of emotion and brain damage
different emotions activate different brain systems fear in amygdala
brain damage - damage can selectively impair emotion recognition, amygdala -> no recognition of fear
amygdala damage
reduced sensitivity to facial expression of fearreduced sensitivity to sound of fear
reduced experience of fear
patients lacking amygdala look less at the eyes. therefore do not notice the open eyes of fear expressions
disgust
what induces it
what is the utility of disgust
contamination from food etc
moral transgression
helps us avoid illness
closes off senses and stops ingestion
what are of the brain does disgust activate
insular cortex
understanding emotions and empathy
can map brain for pleasure / disgust sight and experience of
emotion perception - see reactions to an odour
emotion experience - smell odours
sight in the insula scanned, see disgust > see neutral
brain regions for odours
anterior insula activated only by unpleasant odors
is the same brain region activated by smell and sight
-> insula stimulation evokes taste and odour experiences
empathy
where in the brain
what
why
insula cortex
processes sight of others disgust expressions
processes unpleasant tastes, smells
- we understand others emotions by matching to our own emotions
witnessing others disgust activates our on insulas as if we are disgusted
contagious emotion response aids social learning, eg fear of snakes
disgust expression
brain imaging
brain damage
disgust emotion activates insula cortex
brain damage
damage to the insula cortex or basal ganglia in huntigtons disease impairs disgust recognition
huntingtons disease relatives without clinical symptoms show impairment in recognising disgust expressions
classification of expressions
categorizing mixed emotions is hard
expressions are often ambiguous
depends on the context
disorders with biased emotion processing
negativity bias in depression
hostile attribution bias in conduct disorder
assuming hostility is rational in adverse environment, but may be self reinforcing
vicious cycle in aggression
biased negative interpretation of another’s expression leads to an aggressive reaction which is reciprocated
establishing a virtuous cycle
shifting the interpretation bias set up a virtuous cycle in which positive reactions are reinforced
modifying emotion perception experiment
trained participants (adolescent males)
shift emotion attribution - see less anger and more happiness
report lower levels of anger
staff report less aggressive behaviour in adolescents with criminal records in 2 weeks after training
conclusions in the perception of emotional expressions
bias in the perception of emotional expressions has a causal role in subjective anger and aggressive behaviour
biased emotion perception may contribute to mood disorders
social signals for interaction - gaze, where in the brain
ventral thalamus
activity modulated by attractiveness and gaze direction
attraction and eye contact
brain reward system activated by attractive faces looking at you (unattractive faces looking away)
2 social signals for interaction
gaze - kampe
expression - O’Doherty
attraction and interaction
attractiveness is abstract
attraction to you is important
looking and smiling indicates attraction to you
faces attracted to you activate reward systems
emotion recognition
brain systems - specific emotions
empathy - analysis of own and others emotions
social learning - contagion of fear or disgust
biased interpretation - psychopathology
regulates - aggression
how we see in 3D (cues available to painters)
height in the field of view - further away an object, the higher in the visual field, the lower it projects on the retina
geometric perspective - parallel lines appear to converge with distance
texture gradient - finer (denser) texture is seen as further away
size of familiar objects - object size decreases with increasing distance, if size know distance can be gauged
occlusion or overlap - close objects overlap far objects
blurring and increase of blueness - distant objects = hazy or blurred, dust particles scatter light (depending on wavelength of light) so distant objects appear more blue as will have a different wavelength when they reach your eye
shadow - more ambiguous as we must assume light direction to see cue
pictorial cues - again ambiguous, many 3D situations produce the same 2D image
the hollow mask
light direction interpreted so that hollow mask appears as a solid face
seeing depth and distance - unambiguous cues
dynamic cues - motion parallax accommodation -focus of the eye binocular sues -binocular convergence stereopsis accommodation and binocular cues only work for close distances
relative motion or motion parallax
when we travel in one direction, stationary objects move opposite to our direction of travel
the speed of relative motion is related to distance
close objects appear to move fast, far objects slow
what are binocular cues
cues of convergence of eyes having to converge more for close objects to bring them into focus
what is stereopsis
left and right eye differ
they don’t have the same view
discovered by the victorian stereogram (red and green glasses that makes it seem 3D
definition of a visual illusion
why do we study them
illusions occur when what we seen does not correspond to what is physically present in the world
we study them as they tell us things about normal vision
what do brightness after effect and colour after effect tell us about vision
pigment bleaching / neuronal fatigue and opponent processing of colour
reconcile
ng colour theories
three colour receptors feed to ganglion cells
lots of green light, receptors adapt, post adaption see too much green
motion after effect
waterfall illusion, spiral after effect
explanation - neuronal fatigue and opponent processing of motion direction
illusions over time
examples and perceptual principles
brightness after effect colour after effect motion after effect orientation after effect perceptual principle adapt to a steady state code (overemphasise) change in values across time
illusions over space examples
conc
brightness contrast
object brightness coded relative to the surround brightness - so square appears darker on a lighter background
colour contrast
object colour coded relative to surround colour
motion contrast
orientation contrast (Zolner illusion
visual qualities are coded relative to the surround
what is the Zollner illusion
orientation contrast
lines appear orientated differently when covered in lots of parallel hashes
illusions of size
geometrical illusion
ponzo
muller-lyer
ames room
size distance relationship
object size is inferred from perceived distance and image size
for 2 objects with the same image size, the object appearing further away is seen as larger
the ponzo illusion and gregorys theory
two parallel lines same size but one higher up page made to look further away so perceived as bigger
gregorys theory - the visual system makes hypothese about distance to objects based ont he evidence in the image. interpretation of size follows
Muller-lyer illusion
objectively equal in separation, percpetuaqlly different. way two lines split, made to look different in size when actually the same
perceptive cues set up false interpretations of distance
ames room
room set up to screw with size and distances for the observer
room has false distance cues. left and right corners appear equally far but are not
objects at different distance appear equally far (retinal size differences are seen as real size differences)
Richard Gregory carpentered theory
population from more carentered environemtns see more right angles so fall for the illusion more?
in reality noce idea but not true in practice
illusions occur in populations across the world
impossible figures
penrose triangle
escher’s prints
brain cannot compute 3D structure from all parts at once, each part looks plausible in isolation
ambiguous figures
necker cube - 2d images have one or more 3d interpretation
entertain each interpretation, but only one at a time
conditions for motion perception in apparent or phi motion
lights flashing with close separation and short time interval = motion
wide separation or long time interval = no motion
utility of motion
rigid structure articulating structure heading direction maintain posture interpreting causality attributing goals
what are the mechanisms for detecting motion direction
local inhibition in one direction
detects real or apparent motion in direction, opposite to inhibition
cartoon motion explained
again apparent or phi motion
relies on apparent motion
brain interpolates smooth change in shape
controlling posture
experiment
postural stability - posture is less stable with closed eyes
lee’s swinging room - when te room moves, visual motion is attributed to body motion which causes inappropriate posture compensation
optic flow
j. Gibson
focus of expansion = heading direction
landing a plane on an aircraft crrier
estimating time to contact
lee
rate of expansion predicts when to react
kinetic depth use
circling ballet dancer, can detect shape from changing silhouette
detecting form from motion
rigid motion - kinetic depth, shape from changing silhouette
biological motion - form moving body from lights on joints, biological motion
perception of causality in collisions (michotte)
impression of causality - one object bumps into a second objects stops, then second object moves off
reduced impression of causality
second object moves off before the collision
second object moves off after a long delay
attribution of pupose Heider and simmel
cartoon moves in which actos are arbitray shapes with trajectories appropriate for meaningful actions
subjects attribute actions and intentions to the moveing shapes (eg big triangle chased the little triangle)
habituation paradigm
repeat film until infant observer is bored
change film
measure renewed interest
violation of expectations - surprise and long looks
motion defining goals
behavioural sensitivity
1 year olds infer unseen goals ie are sensitive to the likely goals of an action
increased attention if agents action is inconsistent with earlier goal - catching a small ball
does not take shortest path to small ball
continues on non-intercept trajectory
brain processing of motion and form
v1 and v2 features outputs on motion and IT colour and form to STS
what does biological motion do
activates specific brain regions
motion processing in the brain (cells)
V5 cells are motion sensitive
v5 damage causes motion blindness
inability to track fast movement
see a series of frozen snapshots
evidence for top-down processing
anatomy context imagination observer bias priming expectations
bottom up processing
high level object detections
mide level pattern detectors
low level feature detectors
top down influence
memorized concepts
high level object detectors
mid level pattern detectors
bidirectional processing models
information flow is bottom up and top down
expectations lower threshold for likely items
anatomy to determine whether top down or bottom up
eye -> lgn < v1 < v2 < v4 < temporal cortex
more connections descend than ascend
only 3% of v1 input layer synapses are from lgn
vision = 97% reconstruction or halucination
context of an object
within a scene it is easier in a context to find an image where it belongs in an image than in an obscure place
within an object - word context biases interpretations, jumbled letter judged based in context of word
word superiority effect
detecting a ltter in is easier when in a word
can visual areas be activated without visual input
brain areas processing sight of faces and places fusiform face area, parahippocampal face area
imagine doing thigs - can detect awareness
expectations - object permanence
we expect an object moved behind a screen to reappear with the same form when screen removed
under 8 months abort search if object is hidden
object permanence food location
tinklepaugh - monkeys
clayton - scrub jays
remember the reward value of hidden objects
perceptual priming
conscious and subliminal
rapid cereal presentation
brief images are seen but memory is fleeting
they may not achieve full awareness but can affect recognition and bias behaviour
the rord alzeihmers can impair memor performance
the word fast speeds up reading and walking
signal detection
hits and misses
reward for hits and no penality fro false alarns - encourages target present bias
no reward for hits and severe penalty for false alarms encourages target absence bias
bas affected by
subject confidence
% trials target present
payoff detecting / missing targets
payoff matric
consider benefits from hits and correct rejections
types of eye movements
fixations (pauses) when the eyes are still 3-4 per second
saccades (jumps) between fixations
slow tracking following a moving object
functions of eye movements
to direct fovea to features of interest
why does the world appear static when our eyes move
vision turned off during eye movement
we cannot see our own saccades in a irror
relative conditioning of motion
inhibition between similar motion detectors
compare movement predicted and occuring
stability of the visual world
feed-back from stretch receptors in the eye muscles
feed-forward from planed movements (von Holst)
efference copy of commands to move eyes cancels incoming image movement
evidence for feed-forward
passive eye movement - press eye gently, scene moves
paralysis of eye muscles, try to move paralysed eye, scene jumps
general principles behind stability of the sensory world
attend to unpredictable events
ignore predictable consequences of own actions
unstable sensory world
schizophrenic hallucinations?
sub-vocal speech not recognised as self-generated
own actions and thoughts controlled by others
factors affecting face attractiveness
face owner averageness symmetry sexual dimorphism - masculinity in men, femininity in women health face admirer hormone levels own status imprinting theory - immune competence handicap hypothesis
composite faces
averageness
blending a group of faces shows consisitent traits and looks the most attractive
skin texture gets smoother
face becomes more symmetric
evolutionary explanation
avoid extreme mutant genotypes
psychological explanations - we like what we see often
is averageness as attractive as it gets
no
attractive faces are systematically different from average faces
evolutionary theory of attractiveness
female investment eggs (bigger than sperm) gestation incubation lactation nursing so females choosier than males, exception sea-horses and stickleback
symmetry in attractiveness - animal world
left = right for population low fluctuating asymmetry shows coped with challenges during growth indicates health ad immunity tail symmetry is preffered in swallows is symmetry attractive in humans
symmetry in humans attractiveness
more symmetric face shape preffered
evolutionary theory - what do females
low fluctuating asymmetry, ability to grow / plan
hnest signals of a costly handicap
immune competence - testosterone surpresses immunity; only fit males can afford testosterone cost
predicts sexually dimorphic male traits
male masculinity shows…..
attractiveness?
shows strength and immunity
should it be attractive
surprising aversion to masculinity (shown by women)
feminine warm and hinest whereas masculine is cold and dishonest
sexual selection for parental care
selection may show preference for facial features indicating paternal investment
high testosterone inked to marital problems (mazur and booth)
do mate preferences change over a woman’s menstral cycle?
conception most likely in follicular phase
women select most attractive face and report cycle pahse
increased attraction to masculinity when fertile
preference for masculinity due to relationship desire
preferences for masculinity follows fertility for short bt not long term relationships
parallel effects for voice, dominant behaviour, body shape, pheromone odour
male choice of partner
selection occurs for both sexes
in several primate species females compete for males attention
high oestrogen is associated with health and fertility
feminized female features (face, voice, body shape) should be attractive to men
feminised features in female faces are attractive to men
if humans compete for partners how will partners pair up
own status and competition
women report own attractiveness and judge faces for
-long term relation
-short term relation
chose faces manipulated in masculinity or symmetry
more attractive women prefer what features
attractive women prefer more masculine men
attractive women prefer more symmetric men
competition and mate preferences
for long term relationships, less attractive women prefer lower level of masculinity and focus less on symmetry
interpretation
attractive women may extract greater commitment from symmetric / masculine men
we learn attraction to individuals we can get / keep
imprinting on parent characteristics
imprinting - early exposure to parent traits affects later mate preferences in birds and mammals
Lorenz’s birds
male lambs fostered by female goats prefer goats to sheep as sexual partners (Kendrick et al)
imprinting in humans?
does a human resemble a woman’s father or mother
opposite sex parent and partner are similar
imprinting on opposite sex parent
odours found attractive
pheromones - airborne chemicals influencing physiology or behaviour
awareness not needed for effects
Gibson’s theory of direct perception
visual information controls actions directly
visual properties of objects afford actions
we recognise which actions can be achieved
perception and action where in the brain
occipital lobe
direct control of actions - parietal lobe
recognition and memory - temporal lobe
where and what pathways
ventral pathway damage
cannot recognise objects, orientation, size
patient DF poor at matching handle to target orientation
but patient DF cam guide actions visually
action pathway
dorsal pathway v1 -> parietal lobe
damage = ataxia; cannot guide actions but can recognise objects
perception pathway
ventral pathway v1 -> temporal lobe
damage = agnosia: cannot recognise objects but can guide actions
visual illusions - does it effect motor
red circle surrounded by different shaped circles, makes the red circle appear bigger or smaller (visual illusion)
visual control of action does not suffer illusions
grip size during reaching under online visual guidance is accurate
are the motor and the perceptual systems integrated?
motion primed by actions experiment
stimulus - rotation with ambiguous direction
response - turn hand, think
turn clockwise
percept - display moves with your action plan
interpretation - common code for perception and action control
see intended or associated effects of action
mirror neurone systems
premotor cortex
cells fire during performance of hand actions
cells fire when other seen or heard doing the same action
interpretation
seeing and doing use same brain systems
action recognition depends on production ability
understanding actions and mirror neurones
premotor cortex mirror neurons
discharge during the observation and execution of an action
discharge when the action goal hidden but can be deduced
discharge when an action can only be hear
could enable understanding actions of others by translating them into our own actions
support imitation or empathy?
seeing or doing
does our brain systems respond to the sight of actions because they are familiar or we know how to do the actions
how do we test this
what is the result
ballet dancers have visually familiar but not performed dance moves and otorically familiar dance moves due to different sexes having different moves
premotor and parietal cortex
active more to seeing own-sex than other-sex dance moves
same and opposite sex dance moves were equally visually familiar
mirror systems active when see actions with out motor repertoires
analyse their actions in terms of how we would perform them
does observing someone else being touched activate our own somatosensory cortex - experiment
movies of actors being touched on their legs
touch of the subjects legs
hypothesis - some brain areas activated by both sight and touch
primary somasensory cortex
sight of touch > non-touch
see touch, feel touch overlap
social perception summary
seeing or hearing others actions activates our premotor action plans as if we do the actions
witnessing touch activates our secondary somatosensory cortex as if we are touched
witnessing others disgust activates our insula cortex as if we experience disgust
witnessing others in pain activates similar brain regions to experiencing pain ourselves
action perception and production summary
TMS (trans-cranial magnetic stimulation) of motor cortex produces electrical potentials in muscles
seeing actions using the same muscles reduces the threshold for TMS produced muscle potentials
hearing speech and seeing lip movements increases tongue and vocal muscle excitability
what is motor theory of speech perception
we stimulate production of speech we hear
what is the benefits of attention
can benefit processing
attending on to one object types
-boosts sensitivity
-boosts activity in relevant brain system
what area of the brain attends to faces, houses?
faces - fusiform face area
houses - parahippocampal place area
gorilla experiment
85% miss the gorilla in an image when cancer screening
what is inattention blindness
subjects attending to one object or position can be blind to other objects or unexpected events (neisser)
subjects must attend to objects to notice them but attention may not be enough
changes (saccades and events) can distract us
change blindness
while a door is carried between people, one person changes identity 50% of observers don’t notice the change
simons and Levin
flashing within a screen does what
decreases the chance of seeing other changes
change blindness - when do we miss change
if it happens slowly
if an irrelevant transient (flash, occlusion, saccade) occurs between the original and new forms
movement can itself prevent us noticing colour changes
hemi-spatial neglect explained
damage to right temporal / parietal cortex
inattention to left side of space and objects
cross items only on right of display
bisect right of lines
draw only right side of objects
evidence for coding of attention direction
2/3 cells code gaze and face view
2/3 cells code face and body view
gaze > face > body
wrong gaze inhibits correct face view
problems processing gaze
autism
shyness
autism and gaze
spontaneous attention following deficit in autism
but good at gaze geometry - can work out where picture was looking
how do we use attention direction
competition get food out of dominants sight (chimps) re-hide food if seen define what others know or believe knowledge used competing / cooperation social learning objects of fear words for objects looked at
nature vs nurture, learning to see who and brief what they think
nativist - Descartes, percpetual abilities inborn
empiricist - Berkeley, perception depends on experience
sources of evidence (just titles) in nature vs nurture debate on learning to see
infant abilities
restored vision
cultural differences
adaptation
infant abilities of vision - brief
Gibson - visual cliff, size constancy - bower
face perception
object perception
visual cliff
Gibson - visual cliff, (can only test once mobile but infants avoid the visual cliff, done on goats who are walking from day one and they avoid the cliff. rats don’t)
suggest innate
infants object perception
bower - size constancy
trained head turn response with peekaboo reward generalises to trained size at changed distance
face perception in infants
fantz, goren et al, h=Johnson et al
looking preferences for 2 min olds of facial configurations
and potentially imitate facial gestures
neonate imitation
meltzoff and moore
Ferrari et al
infants imitate tongue protrusions
but also will imitate if any object comes near so up for debate
recovery from blindness
abilities present -figure ground degregation cross modal matching touch to vision problems in interpretation -unknown experience before blindness adult knowledge used in interpreting vision degeneration of the visual system
experience and the nervous system
visual cortex
temporal cortex
orientation sensitive cells present at birth
visual environment influences the distribution of orientation sensitive cells
critical period of influences (3-7 weeks in cats)
temporal cortex
cells responsive to simple aspects faces may be inborn
but show effects of experience
effects of culture in experience and perception
effects of culture
recognition of letters and words
inuit perception and discrimination of snow
colour words blue and green
adaptation to prisms
chicks
motor system matures; consistency in aim increases
but ability to hit target does not
humans
prisms shift the visual world in one direction, adaptation in humans
visual - motor coordination compensates
adaptation leaves an after effect
behaviour biased in compensatory direction
adaptation to inverted vision
initially world looks upside down (and is sickening)
after weeks of adaptation world looks normal
motor skills return - cycling, skiing possible
adaptation to prisms
why should the system adapt
limbs grow
eye changes shape
need to re-calibrate visuo-motor coordination
