Lecture 1: Intro & Visual Development Flashcards
reasons to learn about child development
- Raising children
- Choosing social policies
- Understanding human nature
raising children
Child development research helps answer questions about how to raise children
choosing social policies
Child development research can help inform social policies that affect children
understanding human nature and individuals
- Child development research is vital to understanding how nature and nurture shape human psychology
- Can also help explain individual differences between people
child
every human being below the age of 18 years
what does it mean to be a child?
- dependent on adult caregivers
- fundamentally about learning
humans’ childhood length
- Longer childhood compared to other species (Humans have the longest childhoods among primates)
- Long childhood makes them very vulnerable; thus, caring for them is very time-consuming
learning during childhood
- Long childhood is adaptive for maximizing learning
- A focus on learning is only possible if they are taken care of by adults
Large-brain, narrow hips trade-off
- Our brains are large for our size and more complicated/neuron-dense than any other animal
- Larger brains necessitate larger heads
- At the same time, the evolution of our ability to stand upright favoured narrower hips
how was the large-brain, narrow hips trade-off resovled?
- To solve this, babies evolved to be born earlier
- The brain continues to develop once born, allowing for more learning
what aspects of childhood demonstrate that children are adapted to focus on learning?
- Highly curious
- Highly suggestible, not critical thinkers
- Readily imitate others
- Overestimate own abilities
- Brains are malleable
child development
The process of learning perceptual, cognitive, emotional, and social capacities that allows an individual to grow from the dependence of infancy to the independence of adulthood
why do we focus on infancy when studying child development?
- Very rapid changes in the first 2 years of an infant’s life
- Changes in one area enable changes in other areas
- Methods for studying infants are different than methods for studying older children who can communicate more clearly with adults
- Sheds light on the nature/nurture debate
what do babies see?
From birth, babies visually scan the environment and pause to look at stuff
methods in infant research
- Preferential looking paradigm
- Habituation paradigm
what does the preferential looking paradigm take advantage of?
infants’ preference to look at “interesting” things
preferential looking paradigm method
Present the baby with 2 stimuli beside each other at the same time
interpreting the results of the preferential looking paradigm
If the baby looks longer at one stimulus than the other, it means that:
1) They can distinguish between the two & 2)
Have a preference for one over the other
what does the preferential looking paradigm assess?
infants’ preference for stimuli
what stimuli do infants prefer to look at?
- More complex
- More saturated in colour
- Familiar
two types of familiarity
lab-induced & natural
natural familiarity
stimuli infants experience often in their lives
lab-induced familiarity
familiarize infants with a stimulus by exposing them to it for some time
what does the habituation paradigm take advantage of?
babies’ natural preference for novelty
what does the habituation paradigm assess?
infants’ ability to discriminate between stimuli
three phases of the habituation paradigm
- habituation phase
- test
- dishabituation phase
habituation phase
- repeatedly present an infant with a stimulus until they habituate to it (reduced or stopped response to a stimulus)
test phase
present the habituated, old stimulus with a new stimulus
dishabituation
if the baby shows greater interest in the new stimulus, they can tell the difference between the two
interpreting the results of the habituation paradigm
If the baby looks at stimuli equally, they can’t tell the difference between them
familiarity vs. novelty
- In general, infants show a preference for familiar stimuli
- Prolonged/repeated exposure to a stimulus will cause infants to shift their preference to a novel stimulus
familiarity vs. novelty in lab settings
Short exposure= familiarity preference
Long/repeated exposure= novelty preference
implications of the preferential looking & habituation paradigms
- Exposure time in lab-induced preference procedures needs to be long enough for the baby to become familiar with the stimulus but short enough so that they don’t get bored (habituation)
- Habituation paradigms need to repeat the presentation of a stimulus enough times to ensure that the infant is bored
visual acuity
Sharpness of visual demonstration
how is visual acuity assessed in infants?
the preferential-looking paradigm
preferential-looking paradigm for visual acuity method
Infants are presented with a succession of paddles with increasingly narrower stripes and narrower gaps between them until the infant can no longer distinguish between the striped paddle and the plain gray one
visual acuity at birth
At birth, infants have poor visual acuity
what patterns do babies prefer to look at at birth?
They prefer to look at patterns with high visual contrast
what patterns do infants struggle to discriminate between at birth?
They don’t discriminate between stimuli with lower contrast sensitivities
why do babies struggle with visual acuity at birth
the immaturity of cone cells in infants’ retinas
when does adult-like visual acuity become present?
8 months
colour perception at birth
infants see in grayscale
colour peception at 2 months
colour vision appears
what is the first colour we perceive at 2 months?
red
colour perception at 5 months
adult-like colour perception; can discriminate between colour categories and between hues of the same colour
why does adult-like colour perception emerge at 5 months?
Due to the maturity of cones and visual cortex
how do we know when colour perception develops?
the habituation paradigm
visual scanning at birth
- infants can their visual environment and pause to look at something
- But, they have trouble tracking moving stimuli because eye movements are jerky
visual scanning at 4 months
able to smoothly track moving objects if they’re moving slowly
visual scanning at 8 months
adult-like visual scanning; can smoothly follow objects
why does visual scanning improve at 8 months?
due to brain maturation
why is visual scanning important for infants?
The ability to visually scan is important because one of the few ways that infants have control over what they observe and learn
face perception in newborns
Newborns show a preference for faces or face-like stimuli vs. non-face-like stimuli
the fusiform face area
the region of the brain, located in the temporal lobe, that becomes activated during face perception
face percepetion in infants experiment method
Using the preferential-looking paradigm, researchers showed babies:
- Regular faces
- Upside down faces
- Scrambled, top-heavy faces
- Scrambled, bottom-heavy faces
faces are special hypothesis
If faces are special, babies should always prefer to look at upright faces
top-heavy stimuli hypothesis
If there is a general bias for top-heavy stimuli, babies should prefer an upright face and scrambled top-heavy faces
face perception in infants findings
- Babies prefer an upright face over an upside-down face
- Babies prefer top-heavy scrambled faces vs. bottom-heavy scrambled faces
- This suggests that the preference for faces is simply the result of a general preference for stimuli that are “top-heavy” rather than “bottom-heavy”
seeing mom’s face
- Infants very quickly learn to recognize and prefer their own mother’s face
- Just a few days after birth, babies prefer their mother’s face compared to another woman’s face
infants as face specialists
They are better at distinguishing between faces that are frequently experienced in their environment
evidence for infants as face specialists
- 9-month-olds (and adults) can distinguish between 2 human faces, but struggle to distinguish between 2 monkey faces -> specialist
- But, 6-month-olds are equally good at distinguishing between human and monkey faces -> generalist
perceptual narrowing
Tuning of the perceptual mechanisms to the specific sensory inputs that infants encounter in their daily life
effects of perceptual narrowing
- Improves perception of stimuli encountered often
- Decline in the ability to distinguish stimuli that are not present in the infant’s environment
what perceptual domains is perceptual narrowing present for?
several perceptual domains
what causes perceptual narrowing?
synaptic pruning
synaptogenesis
the formation of synapses between neurons
when does synptaogenesis occur?
right after birth
result of synaptogenesis
hyper-connectivity in the brain
synaptic pruning
the elimination of synapses to increase the efficiency of neural communication
what principle does synaptic pruning follow?
the “use it or lose it” princinple
evidence of perceptual narrowing in face perception
- Infants becoming face specialists
- Infants demonstrate the other-race effect
other-race effect
People find it easier to distinguish between faces of individuals from their own racial group than between faces from other racial groups
other-race effect in infants study method
Researchers recruited Caucasian infants and habituated them to a face from their own race or from another race. They then presented the habituated face with a new face from the same race
other-race effect in infants study findings
- 3-month-olds: can distinguish between faces of all races
- 9-month-olds: can only distinguish between faces of their own race
is the other-race effect due to exposure or is it innate?
it’s due to exposure
what faces are babies most exposed to at birth?
During the first few months of life, 96% of faces that babies are exposed to are females from their own race
other-race effect in babies equally exposed to different races
If the infant is equally exposed to faces of different races, they will not show this effect
face perception in people with ASD
People with Autism Spectrum Disorder (ASD) often have difficulty with face perception
preferential looking paradigm in toddlers with ASD
Toddlers with ASD preferred looking at geometric shapes over pictures of people
(opposite for typically developing kids)
____ is an early indicator that an infant might later be diagnosed with ASD
Infants’ preference for non-faces
perceptual constancy
The perception of objects as being constant in size, shape, colour, etc. despite physical differences in the retinal image of the object
perceptual constancy in infants study aim
Is perceptual constancy present from birth?
perceptual constancy in infants study method
The habituation paradigm with newborns
perceptual constancy in infants habituation process
- repeatedly show an infant a small cube
- The cube is shown at different distances on each trial
perceptual constancy in infants test
- Show infants the original, small cube and an identical larger cube
- The larger cube is farther away so that both cubes project the same-size retinal image
perceptual constancy in infants results
- Infants looked longer at the larger but further away cube
- This indicates that they see it as different in size from the original, smaller cube
- This means that infants saw the repeated presentations of the original, small cube as a single object of constant size, even though the retinal image varied
perceptual constancy in infants takeaway
perceptual constancy is present from birth
object segregation
The ability to identify that objects are separate from each other
what cue is important for object segregation?
movement
object segregation in infants study aim
determine if object segregation is present from birth
object segregation in infants study method
Habituation paradigm with newborns and 4-month-olds
object segregation in infants habituation process
repeatedly watching a video of a rod moving side-to-side behind a box
object segregation in infants study test
Infants are shown 2-rod stimuli moving side-to-side (One rod vs. a broken rod)
object segregation findings in 4-month-olds
- preferred to look at the broken rod
- They see the broken rod as novel
- This indicates that they understood that the rod behind the box is one object
object segregation findings in newborns
- looked the same amount of time at the broken rod and the single rod
- This indicates that they did not understand that the rod behind the box was a single object
object segregation study takeaway
Object segregation is not innate; it has to be learned with experience
binocular disparity
the difference between the retinal image of an object in each eye that results in two slightly different signals being sent to the brain
binocular disparity in the visual cortex
The visual cortex combines the differing neural signals caused by binocular disparity
when is binocular disparity perceived?
4 months old
sensitive period
a period during which experience shapes the development of ability more than at other times
sensitive period for binocular vision
from birth to age 3
visual input and binocular vision
- Depth perception from cue of binocular disparity is a natural result of brain maturation as long as the infant receives normal visual input
- If infants do not receive normal visual input until age 3, they may fail to develop normal binocular vision and have life-long difficulties with depth perception
monocular depth cues
depth cues perceived in one eye
when are monocular depth cues perceived?
6-7 months
how is monocular depth perception measured?
the visual cliff
visual cliff findings
6 month-olds will not crawl over a visual cliff but younger children will
what does the visual cliff demonstrate?
that monocular depth perception needs to be developed through experience
visual development timeline
- At birth: rudimentary visual scanning, poor acuity, preference for high-contrast, grayscale, preference for faces vs. non-faces, perceptual constancy
- 2 months: colour vision appears
- 4 months: Object segregation and binocular depth perception appear
- 5 months: adult-like colour perception
- 6 months: face generalists, monocular depth perception appears
- 8 months: adult-like visual scanning and acuity
- 9 months: face specialists through perceptual narrowing
innate aspects of vision development
perceptual constancy and preference for top-heavy stimuli
aspects of visual development that improve with brain maturation
visual acuity, colour perception, visual scanning, and binocular depth perception
experience-dependent visual processes
- Object segregation
- Face perception (perceptual narrowing)
- Monocular depth perception
- sensitive period of binocular vision
intermodal perception
The coordinated perception of a singular object or event through 2 or more sensory systems
when is intermodal perception generally present?
very early on
combining vision and touch study method
preferential-looking procedure
combining vision and touch preferential-looking procedure
infants sucked on a pacifier that they couldn’t see. They looked at a picture of the pacifier they had sucked on vs. a picture of a pacifier of a different shape and texture
combining vision and touch study results
newborns looked longer at the pacifier they had sucked on (the familiar one)
combining vision and touch study takeaway
This shows that the ability to combine visual information with touch is present from birth
combining vision and auditory information study method
preferential-looking procedure
combining vision and auditory information preferential-looking procedure
4-month-olds simultaneously watched two videos side by side (one of someone playing peekaboo and one of someone playing drums). At the same time, they heard audio of a person saying “peekaboo”
combining vision and auditory information study results
Infants looked more at the person playing peekaboo vs. the person playing drums
combining vision and auditory information takeaway
This shows that infants can integrate visual and auditory information
application of combining vision and auditory information
This is important for language development because children need to understand that speech sounds are linked with a moving mouth
development of monocular vs. binocular depth perception
binocular depth perception stems from brain maturation
monocular depth perception is dependent on experience
synaptic pruning across domains
- synaptic pruning happens in the first few months for perceptual domains (ex: hearing, vision)
- synaptic pruning happens in the first year for language
- synaptic pruning for higher cognitive/executive functions (ex: planning) happens in early childhood
