Please enable JavaScript.
Coggle requires JavaScript to display documents.
Perceptual Development (Cognitive) - Coggle Diagram
Perceptual Development (Cognitive)
Perceptual development
Development of depth perception
Perceiving three dimensions
Ability to perceive depth/distance promotes survival as prevents falling over/avoids drops
Brain interprets depth cues (features of environment that gives information on how far away objects are
Perception of objects is constant even though seen from various angles/distance
Research into the role of nature
Bower (1971) tested depth perception in 8-17 day old babies
Test looked at baby's reaction when larger moved within 20cm and smaller within 8cm
They could distinguish even though same retinal size
Research into the role of nurture
Hudson (1960) showed several two dimensional drawings to South African children/adults that were (un)schooled
Asked which animal spear was pointing to
Schooled said antelope, unschooled said elephant -> depth perception is learned
How perceptual development can be studied in babies and animals
Preferential looking
Fantz assumed human babies and young animals generally look at interesting things
Measured baby's preference when looking at two objects -> preference showed objects were distinguishable
Habituation-dishabituation
Babies look at new or recent things more, but one used to it, they look elsewhere
Habituation -> baby presented stimulus, when looks away, taken away and re-introduced. Time looking gets shorter until zero
Dishabituation -> baby presented with new stimulus, looks for long time again
Electroencephalogram (EEG)
Brain scanning (fMRI) can't be used on babies as they move too much
EEG can be recorded using geodesic sensor net over head that measures electrical activity over brain
Farzin (2012) found spikes in brain activity caused by visual stimuli (faces). Found babies also use temporal lobe of right hemisphere to look at faces
Dark rearing
Blakemore and Cooper (1970) - if dark reared animals have same perception than light reared, then nature
If animal adjusts and recovers functioning, then nurture
Development of face perception
Fantz found that, in development of procedure, babies showed no preference towards a face, but did to the 'unscrambled' one at three months
Showed development of babies' perception -> as they see and scan more faces, they will see the difference for the 'correct' face
At one week old, babies prefer patterned surfaces to plain ones
At two months, they preferred 3D images compared to flat ones
How babies perceive faces
-Babies' perception of faces change as they change how they scan faces
By 2/3 months, baby looks at centre of face, instead of edges and contours from 1 month
Centre of face implies change in perception of faces -> age 2/3 months, face perceived as a whole rather than a collection of parts
The 'own-race' effect in perceptual development
Found that people distinguish faces of own ethnic group than other groups
Begins in infancy, by 9 months, babies can distinguish between faces of only own ethnic group -> perceptual narrowing
Not true for babies with parents of different ethnic groups. Can also be removed experimentally by showing photos of 'other-race' faces
Gibson and Walk (1960) on the Visual Cliff
Background and aims
Lashley and Russell (1934) -> rats reared in darkness, found both light/dark reared rats jumped with force which varied with distance
Found that depth perception is innate but pre-training for jump was in light so became extraneous variables
Aims:
To investigate the ability to perceive and avoid a drop is learned through experience or is part of the child's 'original endowment' (i.e. innate)
To discover the point in development at which infants can perceive depth, and whether this varies in different animal species - specifically does it come before, after or at the same time as the ability to move around independently?
To test which of two visual cues is more important in depth perception - the density of pattern in the environment (texture) or motion parallax
Method
Lab experiment, repeated measures. IV was whether the babies were called by their mothers from across the shallow side or deep side of the visual cliff. DV was whether or not baby crawled to mother
Animal study was quasi - IV was species, DV was deep or shallow side
Sample
36 human babies age 6-14 months, all capable of crawling
Animals included chicks, lambs, kids, kittens, rates, pigs, dogs, aquatic turtles
Apparatus
Large sheet of thick glass (24cm x 1.8cm) raised 1m above floor. 30cm wide centreboard divided sheet into two sides. One side, chequered material attached directly underneath glass sheet, other side, same material on floor. From centreboard, created appearance of drop
Procedure
Human/non human ps tested individually
Human infant placed on centreboard and mother would move so either shallow or deep side was between them, then encouraged baby to crawl across glass. Observed whether baby complied or refused
Animals, centreboard raised slightly so animal descended onto one side or other. Observed direction animal moved
Controls
Researchers controlled for extraneous variables
Ensured cliff wasn't biased to one side
Control experiment using grey unpatterned surface
Controlling for texture density. To observe at glass-level texture on deep side of cliff seems better than shallow side because they're further away. To control, same trials had increased square size on deep side, so appeared as same size as shallow side
Controlling motion parallax: squares on shallow side appeared to move faster over babies vision when they moved across the glass. To counteract, some trials, researchers attached chequered material directly onto glass on both sides. Made squares look larger on shallow side, making them look closer
Results
Human babies
9 infants refused to move to centreboard
Of 27 that moved, all crawled onto shallow side at least once
Only 3 crawled onto deep side, some crawled in opposite direction, some cried out of frustration, many refused to crawl even after touching the glass
Young animals
Chicks, kids, lambs, never stepped onto deep side
When kid/lamb placed on deep side, they froze and became rigid
Hooded rats showed no preference, depend on whiskers to get around so visual cues overrided
When centreboard raised, shallow side preferred 95% of time
No preference in control experiment
Kittens at 4 weeks chose shallow side
Dark-reared kitten had no preference
Kittens kept in normal light conditions and tested on cliff everyday. Showed predictable shallow-side preference
76% aquatic turtles showed shallow side preference
Expected deep side preference due to resemblance of natural environment
24% preferred deep side
Variation implies turtles either have poor depth perception or have no fear of falling
Different visual cues
With only motion parallax, adult rats preferred shallow side but not as strong as original experiment
Infant rates/one day old chicks chose shallow side
90 days, dark/normal reared rats preferred shallow side
Infant/adult hooded rats preferred side with larger pattern
Dark reared rats/one day old chicks showed no preference
Conclusions
Human infants can perceive depth as soon as they can crawl
Behaviour of species consistent with requirements for survival, showed depth perception when most useful for survival
Age depends on species' ecological niche
Depth perception developed regardless of reared in dark or not -> depth perception is innate
Human depth perception develops before controlled movement
Motion parallax innate cue for depth perception, perception of pattern texture density is learned
Play strategies to develop perception in young children
Sensory integration therapy (SIT)
SIT is used to help children develop their perceptual abilities by exposing them to sensory stimuli in a structured, repetitive progressive way
Designed by Ayres (1972), as aid for children with difficulties processing sensory information
May be hyposensitive (don't feel pain) or hypersensitive
Assessment:
Child that has difficulties processing sensory informaation assessed by occupational therapist
Observed child's behaiour and used checklist to diagnose senosry problems
As potential range of affected senses and behaviours so wide, multi-disciplinary team involved in diagnosis
E.g. speech/language therapists, clinical psychologists, audiologists, optometrists, social workers, etc
The sensory diet:
Occupational therapist made programme of sensory experiences, individual to child
Includes activities like cooking, messy play, listening activities, etc
Involves any adjustments made to child's environment
Developing form constancy
Constancy refers to how perceptual system 'knows' properties of an object don't change
'Form constancy' term that covers all constancies
Development of perceptual constancies essential for functioning in everyday life
Used with young children and children with perceptual difficulties
Activities to develop shape constancy:
Use household objects
Child identifies all rectangular shapes in a room, the stands in different place and repeat activity
Shape sorters often used
Activities to develop auditory perceptual constancy:
Children develop ability to know sound remains constant
To develop skills, child says words at varying pitches/accents
Also music is used
Evaluation
Nature/Nurture
Nature:
Gibson and Walk
Chicks, kids, lambs avoided deep side from birth
Nature because it shows depth perception from birth
Nurture:
Gibson and Walk
Babies in study were old enough to crawl to other side
Nurture as environmental factors cannot be ruled out
Ethical considerations
Ethical:
Gibson and Walk
Mothers gave informed consent, and withdraw babies if welfare felt at risk
Ethical as considers consent/protection of participant
Not ethical:
Gibson and Walk
Distress of babies when placed or called to go on deep side
Not ethical as not protecting participants from harm
Psychology as a science
Scientific:
Gibson and Walk
Used experimental method, controlled DV and possible extraneous variables
Scientific as able to establish cause and effect due to no extraneous variables
Not scientific:
Lashley and Russell (background of G and W)
Did not control extraneous variables from pre training
Not scientific due to reduced validity of study
Validity
Valid:
Gibson and Walk
Internal validity -> controlled extraneous variables
Valid as it ensures everything is same for all babies and experiment in general
Not valid:
Gibson and Walk
External validity -> depth perception being innate is extrapolation from animals to humans
Not valid as extrapolation cannot be justified