Lecture 2 - Visual Development Flashcards
Why is Infancy Important?
1) Very rapid changes occur within the first 2 years of life
2) Changes are catalysistic in nature
3) Methods used to study infants are only applicable during infancy (limited window to use exclusive methods)
4) Large source of information for nature VS nurture debate
What do Infants see?
Assumed that infants were blind, however they actually possess the ability to scan and fixate. It becomes difficult to measure what they see since they cannot self-report, so empirical (unconscious) methods are used.
Preferential Looking Paradigm
Assess preference for objects by showcasing them simultaneously and recording which the child stares at longer.
Results suggest 1) Infants can prefer things
2) Infants can distinguish between two different things
According to the Preferential Looking Paradigm, what type of stimuli do children prefer?
More complex, saturated + Familiar Objects.
Habituation Paradigm
Makes use of infants’ innate interest in novel stimuli. Infant is habituated to one object than shown it again alongside a new object. Successful habituation is seen through lessened/ceased interest in the original stimuli and favouring the novel one.
Name 1 way that Habituation and Preferential Looking Paradigm Overlap
They both measure the ability to distinguish between stimuli
With regards to the habituation paradigm, define Dishabituation
When the child prefers the new object over the original one
Give an example of when an infant would prefer novel stimuli and familiar stimuli
Familiar: In general, infants’ prefer familiar.
Novel: However, repeated exposure will lead to lack of interest and infants will then be more likely to prefer novel stimuli.
Define Visual Acuity and how it is assessed.
Sharpness (preciseness) of visual discrimination (telling things apart).
Measured with preferential Looking task; since it is known that infants’ prefer high contrast stimuli (due to poor visual acuity).
Why do Infants have poor visual acuity?
Immature cone cells (we are born not fully baked due to large head- narrow hips Trade-off).
Cone Cells
Light-sensitive neurons involved in colour and fine details,
What is significant about month 8 and visual development?
Infants have fully matured (adult-like) visual acuity.
Provide the Birth-2M-5M Colour Perception Evolution in Infants
Birth=Gray scale
2 Months= Colour Perception begins
5 Months= Adult-like Colour Perception
Quick progression is due to rapid maturation of cone Cells and visual cortex.
What is Visual Scanning and why is it important?
The ability to track and fixate objects in our environment.
First instance of independence in childhood (they choose what they look at).
Provide the Visual Scanning Timeline
Birth= Infants scan and pause
4 Months= Infants can follow slow-moving stimuli
8 Months= Adult-like Visual Scanning, smooth pursuit.
Relies on brain maturation (time gated).
What is unique about infants and face perception?
Infants prefer faces/face-like stimuli.
Due to innate face perception mechanism (FFA) + The fact that we prefer top heavy stimuli (even when scrambled).
Mom’s Face Bias
In the first few days after birth, babies show a bias for mother’s face over the face of a random woman.
Face Specialist VS Generalist
Specialist: Around 9 months of age, can differentiate between two human faces.
Generalist: Before 9 months, can differentiate between faces of two different species but not same, own species.
Perceptual Narrowing + Two perceptual domains in affects.
Tweaking perceptual mechanisms in order to better receive frequently encountered stimuli. Consequently, less frequently encountered stimuli is more poorly received. This process happens across hearing and vision.
Synaptic Pruning
Process responsible for perceptual Narrowing, wherein the brain eliminates neurons and synapses that are inactive in order to increase efficiency of the active ones.
What is the link between Perceptual Narrowing-Pruning-Face Specialists-Other Race Effect
Pruning gives rise to Perceptual Narrowing which is seen through Face Specialists + Other Race Effect.
Other Race Effect
Easier to distinguish between faces of your own race than other races. Not innate, but rather due to exposure, since 96% of the faces that infants’ see during their first year of life are of their own race. Moreover, infants equally exposed to faces of different races do not show this effect.
Synaptogenesis
The formation of synapses, which occurs most rapidly within first year of life, resulting in a very interconnected brain, which is inefficient but malleable.
What is unique about face perception and autism?
Infants with autism struggle with face perception since they avoid eye contact, moreover they prefer geometric shapes of face shapes. These two behaviours are early signs of autism.
Perceptual Constancy
Objects are perceived as constant in size, shape and colour despite being shown to us under different angles, orientations and lighting.
Perceptual Constancy in Infants
Perceptual Constancy is thought to be innate, since infants were habituated to a small cube at different distances, followed by a larger cube placed at a distance that makes it resemble the smaller cube. The infants recognised not only that the smaller cube was one object despite multiple orientations, but also that the larger cube was different from the smaller cube despite appearing to look the same.
Object Segregation
Ability to identify objects that are separate from one another. Movement is a vital cue since objects that move independently are often separate.
Object Segregation in Infants
Learned Mechanism, since after seeing a box move along a rod, newborns and 4 month olds are shown a full rod or two halves. Infants chose the two halves meaning they did not perceive the rod behind the box as one object.
Depth Perception + Binocular Disparity
Depth Perception relies on Binocular Disparity, which is the difference in retinal images between both eyes, both of which are sent to the brain. This difference is caused by the distance between our eyes and the visual cortex combines both inputs in order to create a coherent image.
Not innate, present at 4 Months.
Sensitive Periods
Biological periods in which certain experiences are required in order to achieve development milestones.
Sensitive Period for Depth Perception
Birth-Age 3. So long as the infant is receiving normal input into both eyes, brain will mature on time for sensitive Period.
If criteria is not met, lifelong complications may develop.
Monocular VS Binocular Cues
Binocular Cues, although not innate are better overall, and children only begin being able to process monocular cues around 6-7 months.
Visual Cliff Experiment
6 month olds will not crawl over illusory Cliff but younger infants will. Thus suggesting that monocular cues are experience based.
Provide the Visual Development Timeline
Innate= Preference for high contrast, face like stimuli and perceptual constancy present.
2 Months= Colour Vision Appears
4 Months= Object Segregation and Binocular Depth Perception
5 Months= Adult Colour Perception
6 Months= Face Generalists, Monocular Depth Perception
8 Months= Adult Visual Scanning and Acuity
9 Months= Face Specialists
