perceptial development

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Background: Development of visual perception in children, perception?
cognitive process involving the recognition and interpretation of stimuli once they have registered with our senses.
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How it can be tested in human infants?
Perception of faces
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Perception of faces?
Babies rely on adults, particularly their mothers, to feed and protect them, so it would be adaptive to be biologically prepared to recognise the mother’s face and direct social releasers at her.
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Fantz (1961)?
Presented 4 day to 6 month old infants with circles filled with black shading in patterns designed to represent the features of a face, or spread around the circle, or in one solid block covering half the circle
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Fantz 2?
Babies of all ages showed a slight, but distinctive preference for patterns representing a face suggesting human babies possess an innate preference for human faces over other visual objects
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Some of the infants were old enough that their facial perception could be explained by learning through interaction with the environment, so the conclusion that their facial perceptual skills were innate may be invalid.
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Critique? 2
The stimuli were artificial and had little resemblance to the real, animated and mobile faces that infants would encounter in the real world (low ecological validity).
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Flavell (1985)?
found that babies, presented with faces and other stimuli with similar amounts of movement and contour, showed no preference for faces, lowering the replicability (external reliability) of Fantz’s (1961) results
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Further research supporting Fantz (1961)?
Walton et al. (1992)?
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Walton et al. (1992)?
) filmed the faces of 12 new mothers and then filmed the faces of 12 other women who were matched in terms of hair colour, eye colour, complexion and hairstyle.
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walton (1992)? 2
Neonates (newborns) were then showed pairs of videos – one was of their mother and the other was of the woman who was matched with their mother
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walton 3?
Neonates (newborns) were then showed pairs of videos – one was of their mother and the other was of the woman who was matched with their mother
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what did walton show?
They showed a significant preference for the video of their mother, supporting that face perception is innate as the infant is able to discriminate between the mother’s face and other very similar faces, before the ability could be learned (1 day old
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Population validity is high in this study as the researchers used 1 day olds which represent the target population they needed to measure to determine whether perceptual skills were innate.
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critique? 2
This method relies on babies forming an association between sucking and maintaining the video of the mother on the screen. This may be too advanced a method as the neonate brain is not fully developed, particularly the association cortex.
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critique 3?
Babies may not be showing innate face perception, so the conclusion is invalid, as they may have recognised the mother from the way she moved rather than her facial features.
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critique 4?
Sucking rate is an invalid measure of preference to determine neonates’ facial recognition skills. The infant could increase their suckling behaviour due to other physiological reasons, such as hunger, which would confound the results.
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Shape constancy?
A perceptual skill we demonstrate is the ability to understand that an object remains the same even if it is rotated, and produces a different retinal image.
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Bower (1966)?
used an operant conditioning technique where 2month old infants received a reward when they looked at one object (a rectangle at a 45° angle) meaning they should look at that object again as they associate it with the positive reinforcement.
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bower 2?
The researchers then presented them with 2 objects: a trapezoid which created the same retinal image, and a rectangle that had been rotated at a different angle, which created a different retinal shape.
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bower 3?
Looking was measured by sensors in the infant’s headrest.
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bower results?
The infants looked at the rectangle more, even after it was rotated, demonstrating shape constancy. It is difficult to conclude whether this ability is innate or learned as the infants are already 6months old when tested.
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Babies may become bored of the stimuli being used as reinforcement and therefore may stop looking at the image they were conditioned to respond to.
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critique 2?
The measure may be invalid as infants may turn their heads for other reasons, i.e. seeking mother.
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critique 3?
The way infant’s looking preference was measured was objective (recorded using sensors)- preventing observer bias- observers ignoring looks at the object which was not conditioned.
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How it can be tested in animals?
Animals are often used to investigate whether perception in humans is innate or learned, due to ethical reasons. To isolate whether the cause of perceptual skills is innate
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how it can be tested in animals? 2
infants would have to be raised in sensory deprivation until they’re old enough to be tested. This doesn’t comply with protection from harm, which is an ethical issue in human research.
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Blakemore & Cooper (1970), aim?
To investigate whether orientation selectivity (ability to perceive horizontal or visual lines in the environment) is innate or acquired through experience.
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method/ procedure?
Independent measures design lab experiment where kittens were raised in the dark until 2wks old, and then raised in a lit vertical striped drum or horizontal striped drum until 5months. They were then tested for line recognition
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method/ procedure 2?
the researcher thrust a stick (held horizontally or vertically) towards the kitten- if the kitten could see the stick, it would be expected they would show an innate flinching response.
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method/ procedure 2?
Additionally, the researcher shook a stick in front of the cat, held vertically and horizontally- if the kitten could see it, they were expected to reach for it
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method/procedure 3?
Finally, micro-electrodes were inserted into the brain of one of the kittens and neurons in the visual cortex (V1) were tested to see whether they would respond to the orientation of line the kitten had not been exposed to before 5months
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method/ procedure 4?
if neurons did not activate to that orientation of line, it suggested it was not being processed meaning they couldn’t perceive it.
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Results 1?
At five months the kittens were tested for line recognition. They showed ‘behavioural blindness’ in that those raised in horizontal environment could not detect vertically aligned objects, and vice-versa.
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results 2?
Only the eyes of the cat brought up on vertical stripes followed a rod held vertically and shaken, and vice versa for the horizontal condition
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results 3?
They did not respond to lines orientated in a way they had not been exposed to.
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results 4?
Horizontal plane (line) recognition cells did not ‘fire-off’ in those kittens from the vertical environment, and vertical plane (line) recognition cells did not ‘fire-off’ in those kittens from the horizontal environment.
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Development of the visual cortex continues well after infancy, and is determined by the functional demands on the brain (what it is called upon to do and deal with) rather than by pre-programmed genetic factors.
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Evaluation of animal research into perception?
There are problems generalising from animals to humans. Human perception is more complex, so may need environmental input to develop fully.
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Evaluation of animal research into perception? 2
Additionally, some animals may need more innate skills as they are vulnerable to predators early on, and may be cared for by parents for shorter periods than human infants.
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Evaluation of animal research into perception? 3
Physical and psychological harm caused by animal experiments raises ethical concerns. Cost-benefit analysis can be used as justification: for example, if research leads to treatments for visual impairments, the harm to the animal may be justifiable.
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key reserach? aim?
To investigate whether depth perception is innate or learned.
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Repeated measures design laboratory experiment. The IV was whether the infant was called by its mother from the cliff side or the shallow side (of the visual cliff apparatus).
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method 2?
The DV was whether or not the child would crawl to its mother.
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method 3?
The studies using other species are quasi (laboratory) experiments. The naturally occurring independent variable (IV) was the animal species e.g. rat / chick / lamb / kitten.
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method 4?
The dependent variable (DV) was whether the animal preferred the shallow side or the deep side of the visual cliff apparatus.
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36 infants ranging for 6-14 months (they could only be recruited once they could crawl). Their mothers also participated in the experiment.
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The visual cliff apparatus: a large sheet of heavy glass which is supported a foot or more above the floor. On one side of the board a sheet of black and white checkerboard patterned material is placed flush against the under-surface of the glass
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materials 2?
On the other side a sheet of the same material is laid upon the floor (visual cliff- if you can’t see the glass, it looks like a drop). Reflections were controlled for by using floor lighting.
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Human infants were called by their mothers from both sides of the apparatus, using a wind mill to attract their attention. Animals were either tested the same way as human infants or placed on the shallow and deep sides.
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procedure 2?
In the animal experiments, the apparatus was adapted to control for extraneous variables, i.e. the pattern was placed against the underside of the glass on both sides of the apparatus, in one trial
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procedure 3?
but the pattern was made smaller on one side to make it appear further away if the infant is using relative size (identifying depth from known size, i.e. if the squares on the checkerboard appear smaller it is because they are further away )
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procedure 4?
to judge depth, and, in another trial, larger squares were placed on the deep side to eliminates cues from relative size, meaning the drop could only be perceived if motional parallax cues
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procedure 5?
(identifying depth from the speed objects appear to move across the field of vision when turning your head, i.e. the deep surface will stay within your field of vision longer because it is further away than the shallow surface) were being used.
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procedure 6?
Some animals (rats and kittens) were also divided into those raised in the dark (to control for the influence of nurture on perception) and those raised in lit environments, to determine whether depth perception in this species was innate or learned.
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Results? 1
27/36 infants crawled onto the shallow side at least once. 3 out of the 27 also crawled onto the deep side. This meant 9 of the children would not leave the centreboard to crawl on either side
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results 2?
Many of the infants crawled away from the mother when she called to them from the cliff side and some of them cried because they could not get to her. Often the infants would peer down through the glass on the deep side and then back away.
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conclusions for 1 and 2?
This suggests that infants are biologically prepared to recognise depth cues when they begin to crawl (innate) as it’s adaptive. This ability to learn depth cues quickly has been passed down because it prevents infants from falling and perhaps dying
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conclusions 2 for 1 and 2?
However, in order for a trait to be considered evolutionary, it must be universal (occur in every member of the species), and the 3 infants who behaved differently towards the visual cliff suggest the trait may not be genetic
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conclusion 3 for 1 and 2?
though it could be argued they had some visual impairment or developmental issue which affected their behaviour, or did not have enough experience of crawling to have learned depth cues, even if biologically prepared.
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results 3?
Chicks, tested at less that 24hrs old, and lambs and kids (baby goats), tested as soon as they could stand, never chose to walk on the deep side of the visual cliff. When one of these animals was placed on the glass of the deep side
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results 4?
they showed defensive or fear responses. As these animals could be tested so early on in their development, it suggests that depth perception in these species is innate as they did not have the time to learn
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results 5?
The poorest performance on the visual cliff was shown by turtles, an aquatic species, where falling is less likely, suggesting that depth perception may not be innate in this species, as it didn’t increase the chances of survival in one of a species
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results 6?
Rats raised in the dark showed the same preference for the shallow side as rats raised in lit environments, suggesting -depth perception is innate in rats
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results 7?
Kittens raised in the dark showed no avoidance of the visual cliff when tested at 27 days old. After a week of being exposed to a normal, lit environment though, they developed depth perception, and avoided the deep side.
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conclusion for 7?
This suggests that depth perception is not entirely innate in kittens- it requires some interaction with environmental experience to develop.
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results 8?
In some animals, only motion parallax is an innate cue for depth perception.
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results 9?
They would move onto the deep side of the apparatus if the pattern was on the underside of the glass, even if the pattern on one side was made to look further away by making the squares smaller.
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evaulation? 1
Ecological validity was low as the checkerboard does not represent the complexity of depth cues in the natural environment, i.e. relative size may be less clear in the home environment, i.e. on wooden or carpeted floors
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evaluation 1 extra?
so infants may be less likely to demonstrate depth perception in the real world.
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Hubel & Weisel, 1962?
nfants were old enough that their abilities may have been learned, even that of the chicks, lambs and kids, as previous research has shown the brain adapts very quickly to the visual environment
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Hubel & Weisel, 1962? 2
Therefore, the conclusion that depth perception is innate may be invalid. However, in rats and kitten this was controlled for by raising some of them in the dark.
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evaluation 2?
There may be issues of reliability as some human infants may have avoided crossing to their mothers for other reasons, rather than perceive the depth cues, and other infants may have crossed the visual cliff despite perceiving depth cues
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evaulation 2 extra?
because they were more desperate to reach their mother, or relied on tactile cues to a greater extent.
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evaulation 3?
The materials used (visual cliff) make the study replicable, which allows the researchers to establish generalisability by testing on different populations.
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Schwartz et al. (1973)?
placed babies directly onto the deep or shallow side of the visual cliff, between the ages of 5-9months, to test whether it was the experience of crawling and falling over drops that made infant develop depth perception, or whether it was innate.
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Schwartz et al. (1973)? 2
He measured their perception by measuring their fear response, i.e. through monitoring their heart rate.
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what did schwartz find?
He found that younger infants (closer to 5months meaning they haven’t yet started crawling) showed no response to the cliff, whereas older babies (who were more likely to have started crawling) did show a fear response when placed on the visual cliff
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what do these findings suggest?
This suggests that experience of crawling is necessary for depth perception to develop, suggesting nurture plays a role.
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Application: sensory integrative therapy?
This is often used for children with developmental disorders, like ASD, but could also be used on children who’d experienced sensory deprivation in some form or a delay in perceptual development in some modality (one of their 5 senses).
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Application: sensory integrative therapy? 2
The therapist starts by assessing the child’s individual needs. For children with ASD, or those who’ve experienced neglect, there may be stimuli which they find comforting and some they find distressing,
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Application: sensory integrative therapy? 3
The SI program is designed to be fun and engaging for young children. The key to SI therapy is ‘intrinsic motivation’
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Application: sensory integrative therapy? 3 extra
that is, the children should love doing the activities, so practicing them is positively reinforced/ rewarded by the positive feelings the techniques give them (this is supported by the theory of operant conditioning).
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examples of play activity and how they involve differences senses
Using brushes on the skin (touch and hand-eye coordination) * Sitting or rolling on a bouncy ball (vision and balance) * Being squeezed between exercise pads or wearing a weighted vest (pressure and movement) * Dancing to different types of music
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Application: sensory integrative therapy? 4
Often sensory rooms are utlilised which activate all the senses with coloured lights, surround-sound speakers, sound-to-light-wall-panels, beanbags, textured mats, and aroma diffusers.
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Application: sensory integrative therapy? 5
The therapy involves regular sessions which activate pathways in areas of the brain which interpret senses, such as the visual cortex.
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Application: sensory integrative therapy? 6
Processes of neuroplasticity suggests that if these pathways are repeatedly activated they will be strengthened, improving the development of that area of the brain and its perceptual functions.
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The play strategy is supported by research on infants like Schwartz et al. (1973) which takes an empiricist (nurture) view of perception, suggesting it can be affected by experience
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examples from schwartz?
i.e. infants show depth perception only once they’re old enough to have had experience of drops and falling, from learning to crawl.
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How it can be tested in human infants?


Perception of faces

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Perception of faces?


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Fantz (1961)?


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