Recap: Theories of perceptual development
lNativism: we are born with innate perceptual abilities that develop simply through maturation not learning vs lEmpiricism: we are only born with very basic sensory capabilities, our perception develops through experience and interacting with our environment
lGibson: Ecological, bottom up, direct theory: –direct perception - AFFORDANCES - environment provides information –Learn about environment through perception lGregory: top down, constructivist, indirect –Learning & experiences affects how the environment is perceived
lThere are five ways in which psychologists have attempted to study this debate: –by studying human neonates & infants, –by studying cataract patients, –by studying animals, –by studying adaptation –by studying different cultures..
Human Cataract Patients
lBorn with cataracts, the surgery restored sight as adults. lSimilar to investigating babies -visual use is new and unfamiliar, but cataract patients are able to communicate effectively about what they can perceive
Senden (1932): 65 patients who regained sight afte
lHad same abilities as sighted newborns, i.e. they could tell the difference between the background and an object, they could fixate objects and follow a moving object. lBut unable to recognise simple objects or shapes which they knew by touch. (remember baby and dummy study) lUnable to use sight to make judgements such as which of two sticks was longer. lDid show perceptual constancies, such as shape constancy. lSuggests that experience is crucial for the development of perception.
lThink about: –Methodology –Positive and negative points lGeneralisability of case study research lSample size lDate of research lEffect of mental state on perception
lLike babies, animals can’t to tell us what they perceive but unlike babies we can legally do nastier things to them in the name of research. lMost animal studies focus on the effects of deprivation. –Riesen (1950): lraised chimps in total darkness and found that their visual systems had decayed. lRaised chimps with goggles to let some light in and found that they could perceive some things (brightness, size) but not more complex things (patterns, following movement, depth) suggesting more complex perceptual abilities can only be learned in a more enriched environment.
lWiesel (1982) sewed one eye of a kitten shut and found that if it is done early enough the eye remains blind. lBlakemoore and Cooper (1970) found that by restricting the animal’s visual environment from birth, the perception of some things was extremely difficult
Blakemore and Cooper (1970)
lReared kittens in the dark, except for periods when the kittens were placed inside large drums that were painted on the inside. lSome cats were in a drum with vertical black and white stripes, while others were in a drum with horizontal black and white stripes. At first the kittens could not recognize anything with edges that were different from the one they had seen inside their drums.
Held and Hein (1963)
lKitten carousel - two kittens shared the same visual experiences, but only one could move fairly independently. lWhen their paw-to-eye co-ordination was tested the active kitten had far better abilities. l
Can we generalise from animal studies?
The value of what we find – important advancements in our understanding of development – especially about the timing of sensory experiences
lThese studies aim to find out whether we can adapt to a consistent change in our visual array, e.g. in colour or orientation. If we can this would show that perceptual ability is learned, if we can’t adapt this would suggest that perception is innate. lStratton inverted his vision with lenses in 1896, and found that he was soon able to adapt and carry out complicated procedures like writing and pouring drinks with ease, although better with his eyes closed. lThis suggests that human perception can be learnt.
lSample size! lGeneralisability lUsefulness