Zusammenfassung der Ressource
Perception
- processes that occur in the mind which
convert sensations into a representation of
the world that we can make sense of.
- the process by which the brain organises
and interprets sensory information
- cognition - mental processes - all
the processes by which... sensory
input is
transformed,reduced,elaborated,
stored,recovered and used (Neisser
1967)
- use environment to create
perceptions
- Deregowski (1972)
- 3-d perception of pictures
- people of western cultures
tend to see pictures in 3
dimensions
- cues
- important
- i.e - depth
- judge
distances
- ability to recognise
people
- Kozlowski an Cutting (1977)
- able to show that minimal perceptual info is
needed to identify a moving thing as a person
- Gibson and Walk (1960) walking off a cliff
- sample - 36 infants
ranging in age from 6
months to 14 months
- also tested a variety
of animal neonates
including lambs,
chicks, rats, kittens
and turtles
- visual cliff: shallow side or deep side - thick
piece of glass placed over a wooden box.
Under the glass is a change of levels.
- baby is placed in the middle of the glass and its mother
tries to get it to crawl either over the shallow or the deep
end
- if the babies refuse to
crawl over the shallow end
but refuse to crawl over
the deep end this
suggests they have depth
perception
- if they crawl over the
deep end they have
no depth perception
or they have
guessed the
experiment/ do not
care
- results
- children
- 9/36 stayed where they were
and did not crawl in either
direction. All of the 27 crawlers
moved onto the shallow side at
least once and only 3 crawled
over the deep side
- many kids crawled away from the deepside/ cried when
their mother tried to encourage them. Some peered
through the glass and backed away and others patted the
glass however did not cross the cliff
- suggests babies can also
perceive depth
- animals
- chicks -24 hours - never went over the cliff,
always went to the shallow side
- rats went over the deep side as often as the shallow side -
however rats tend to use tactile cues when moving around
so when the glass was lowered, they close the shallow side
95% time.
- turtles only chose the shallow
side 76% of the time - however
= aquatic creatures and so have
less reason to fear depth
- suggests animals are able to
discriminate depth as soon as they can
move around - has obvious survival value
- also investigated pattern
density
- patterns of different sizes
- rats chose large check but
chicks showed no preference -
shows some animals require
learning (narrow check
suggests depth)
- motion parallax - made checks appear the
same
- rats and chicks still avoided the deep side - use this cue from an early age
- discussion
- the most this study says is that babies as young
as 6 months old can perceive depth
- source et al 1985 -
infants who saw the
fearful face did not crawl
across but infants who
saw the happy face
looked down at the cliff
again and then crossed
to their mother
- if put on a flat plane with
no visual cliff they
crawled over without
checking with their
mother
- it is worth noting the practical and ethical
implications of the study
- 25% of babies did not respond
- babies distressed at mothers
enticing them over a cliff
- Nature/Nurture debate Important but stale Maturation Vs Learning
Internal Vs External Genetic Vs Environment (determined) (imposed)
Nature through Nurture
- It is very difficult to carry out psychological research at the early stages of development only recently that
scientists have taken the view that newborns are not blind and deaf. Kagan (1971)“Nature has apparently
equipped the newborn with an initial bias in the processing of experience. He does not, as the 19th C.
empiricists believed, have to learn what he should examine.” (p.60) taste, touch and smell are fully functional
at birth Newborns can also hear low and mid audible (speech range) frequency sounds Newborns can’t see
very well (technically they are blind)
- Taste, touch and smell are stimulated in the
womb So is audition But it’s like listening to
sound in the bath Though the infant is only
exposed to low and mid audible frequency
range (up to about 6/7000Hz) But what about
vision? Very little light (or high frequency
sound) gets into the womb so the eyes and
the rest of the visual system is
underdeveloped
- We know that infants have certain in built (innate) mechanisms and “…while
infants may not, indeed, see as well as adults do , they normally see well
enough to function effectively in their role as infants.” Hainline & Abramov
(1992; p40) And visual development requires an interaction between the sensory
aspects (colour, movement etc) and the motor system (experience) Remember: It
is difficult to measure perception in very young children
- Motor (eye muscles) Convergence and divergence (movement of the eye muscles) Accommodation (lens)
Binocular (two eyes) Image from both eyes are compared for disparities (e.g., magic eye pics) Monocular E.g.
Linear perspective, Familiar size (size constancy, pattern density, Motion parallax, lighting and shade, texture
gradient aerial perspective )
- walk like a man
- do we need all the info we take in to recognise people?
ie - clothes, face and hair etc
- can we recognise people from
a few simple visual ques? YES!
- Kozlowski and cutting (1977)
- participants - used undergraduates as subjects.
- role was to watch videos and identify if male or female
- participated in groups and for experiments 1 and 3/5 they were payed
- design
- comparison of the study is the comparison of the pattern
of subjects actual judgements with the pattern that would
be seen if they were guessing
- the greater proportion of correct
responses to incorrect responses
means we can be more confident that
subjects are doing more than
guessing
- binomial test used to decide whether the
proportion of correct responses is sufficiently high
to allow us to conclude that subjects can really
identify the sex of the walker
- materials and apparatus
- video recordings of 6 people (3 male and 3 female)
- models walked from left to right and
back again in front of the camera
wearing reflective tape on their
shoulders, elbows, wrists,hips,knees
and ankles.
- in each experiement the
models walked differently
and were in different
orders.
- subjects viewed 10 trials of each
of 6 models, randomly
pre-recorded on video
- write down m or f
- 5 point scale to rate
how confident they
were
- results
- 5/6 walkers were identified correctly in
experiment 1 on the majority of trials (one
woman walker was consistently
mis-identified as male
- overall, subjects made correct judgements on 63% of trials - if
the mis-identified female is excluded from the analysis then
nearly 69% of judgements were correct
- for the trials which participants rated
themselves the most confident they
averaged 87% correct responses
- subjects could tell when
they were looking at a
male or female
- exp 2 - had to identify static people
- only 1/20 guessed the lights
represented people, most guessing
xmas tree lights
- 3 and 4 - effect of different styles of walking on judgement
- did not have any effect - ie arm swing
on judgements apart from making
them less confident and more likely to
guess
- 5 - number and positioning of point
light sources were manipulated
- upper body cues found to be more effective
than lower body cues
- more specificr research needed ie
guessing se with just ankle lights on
- discussion
- insight is used to design modern
computer graphics
- is fastinating
- grammar of movement - increased speed =less grammatical
- can recongise the sex of a person just
from the movement of lights attached to
their body
- Form derived from patterns of movement generated by living
forms Special form of SFM Present very early (4 mnths) in
perceptual development (Fox & McDaniel, 1982; Bertenthal, et
al., 1987) However, experience plays a significant role Some
living object forms are easier to detect than others Human gait
is easier to detect than other animal gait Human figure activity is
harder to recognise if inverted Remains unscathed as we age
- Form Object shape - early stage of identification (area V3) Contours and artificial contours Contours of light
boundaries (EDGES) First step to building up a representation of the visual world (Marr, 1980) Form can be
implied Structure from motion (SFM) Object form can be perceived from movement Very little information is
needed to convey form
- sensation
- initial stimulation of our sensory systems - sight, hearing
- perception is in
effect, derived from
an endless stream of
eternal information
and influenced by
our arousal states
and past experiences
- attention plays a critical role in
making sense of our sensations
- audition (hearing)
- the ear
- detect sound waves
- sounds differ along 3 dimensions -
amplitude, freq and compleity
- outer ear
- compromising of the pinna, the auditory
canal and the tympanic membrane
- the middle
ear
- compromising the ossicles - made up of 3
connecting bones (hammer,anvil and stirrup)
and the eustachian tube - which helps
regulate air pressure
- the inner ear
- compromising the cochlea
- page 86 on taking in sound of
essential psychology
- seeing (visual)
- 80% of info comes from
visual world
- the eye
- light enters the eye through the cornea
- passes through the pupil and is focused
on to the back of the eye (retina) by the
lens
- the retina contains photoreceptor cells called rods
and cones that convert light energy into
electrochemical signals
- rods - extremely sensitive to movement as
they have good temporal resolution but not
to colour and they do not carry fine
detailed information
- cones - responsible for fine detailed
vision in colour
- bipolar cells -repolarise and
hyperpolarise in response to rods and
cones
- blind spot is where the optic nerve is formed
- eye to the brain
- page 89 essential psych
- sensation - the physical stimulation of the
sensory apparatus (effect of light on the retina,
vibrations on ear drum, surface pressure on the
skin etc)
- perception - the faculty of percieving - the ability of the mind to refer sensory information to
an external object and its cause (OED) - the experimental comonent of sensation
- 5 senses
- vision (sight)
- eye -light receptive ganglion on cells in the retina
- stimulus - electromagnetic wave forms
- audition(hearing)
- ear - timpanic membrane (ear drum)
irgan of corti and hair cells
- changes in air pressure =
stimuli
- somatory/sensory/haptics (touch)
- skin - various mechanoreceptors
- stimuli - mechanical pressure/deformations of the skin, changes in temp
- gaustation (taste)
- tongue - taste buds in papillae
- stimulus - chemical substances disolved in saliva
- olfaction (smell)
- nose - cilia in the mucus layer of
the epithelium situated at the top of
the nose and back of the throat
- stimulus - airbourne substances disovled
in the mucus
- brain bits
- primary auditory cortex = hearing
- primary sensory cortex = touch
- primary visual cortext = vision
- amygdala and hypothalamus (taste)
- pitruitary gland (smell)
- recognition
- recognising objects -
recognition is complex
- multi sensory activity
- effortless
- perception is adequate not accurate - multi sensory
- why does perception match
reality? (martin and foley
(1992))
- physical stimuli are rich in information/ the
human sensory system is really good at
gathering info/ concepts shape our
perception
- approaches
- ecological approach
- j.gibson 1950,1965
- perception is
a direct
process
- light is rich in info
- 4 main principles - the stimulus should not properly be
described in terms of the optic array not the retinal image/
perception is not static but active, movement of the observer is
crucial for generating info/ key element of optic aray is
invariant information
- constructivism
- basic assumption - perception is influenced by top down information
- hypothesis and expectations
- 3 shared assumptions
- active and constructive process -
more than sensation
- perception = indirect by product
of external input (sensation) and
hypothesis
- influenced by individual factors
(personal experience/situation)
- gregory 1970,1980,1990 - wiki
- external world is full of info but sensoryinput is impoverished. instead
sensory input form the basis a best guess about the stimuli and the
world
- errors and illusions occur because of these
best guesses
- computational approach
- david marr's 1982 2.5 dimensional sketch
- primarily (not exclusively) a bottom up account
mapping perception to the underlying
physiology
- begins wiith the retinal image and
ending with high level
representation, attempts to explain
how perception is constructed
- identified 3 levels of analysis
- the computational level - what
needs to be figured out
- the algorithmic level - how, what needs to be
figured out, is figured out
- the hardware level - what is it
that does the working out
- 3 stage process - primal sketch > 2.5
sketch >3d sketch