Task 2 Development: Wonder Baby Flashcards
Contrast sensitivity
can detect a pattern only when it is composed of highly contrasting elements
What techniques test visual acuity?
preferential-looking technique and visual evoked potential technique (VEP)
Preferential-looking technique
o Different visual stimuli are typically displayed on two side-by-side screens
o If an infant looks longer at one of the two stimuli, the researcher infer that the baby is able to discriminate between them and has a preference for one over the other
o When infants prefer to look at certain stimuli this is called spontaneous looking preferences
o Infants look longer at objects with contours over ones that are homogenous
Why is infant’s visual acuity low?
cones are immature near the fovea and further apart than in adults, poorly developed visual system forces them to see with rod-dominated peripheral retina
Habituation technique
procedure involves repeatedly presenting an infant with a given stimulus until the infant’s response to it habituates (declines)
o Novel stimulus is presented if infant’s response increases, the researcher infers that the baby can discriminate between the old and new stimulus
Visual Evoked Potential Technique
- Measure acuity through an objective electrical response
- Recorded by disk electrodes on the back of the infant’s head over the visual cortex
- Pooled response of thousands of neurons that are near the electrode
When is the visual cortex fully developed?
6 months
When do infants reach adult’s level of visual acuity?
6 months
Contrast sensitivity
can detect a pattern only when it is composed of highly contrasting elements, infants cannot due to immature cones
Spatial frequency
number of cycles of the grating per degree of visual angle, in which one cycle is one light bar and one dark bar
Contrast sensitivity function
- Used to determine the contrast sensitivity of gratings with different spatial frequencies resulting in a plot of contrast sensitivity vs spatial frequency
- For adults: most sensitive to 3 cycles per degree; ability to see low spatial frequencies drops off rapidly above 10 cycles per degree
- For Infants:
1. The ability to perceive contrast is restricted to low frequencies
2. Even at these low frequencies the infant’s contrast sensitivity is much lower than the adult’s
3. Infants can see little or nothing at frequencies above about 2-3 cycles/degree -> the frequencies adults are most sensitive to
When does colour vision develop?
first 3-4 months
How to test for colour vision development?
Habituation technique
- As the infant becomes more familiar with the stimulus (habituation) it looks less and less each trial
- By presenting a new stimulus one can tell if the infant is able to see a difference by having an increased focus on the new stimulus (dishabituation)
- If the infant can’t see a difference he or she will continue to habituate to the old stimulus
- Result: 4 month old infants categorize colors the same way adults do
Optical expansion
-> when does it emerge?
visual image of an object increases in size as the object comes toward us, occluding more and more of the background (depth cue) – key: movement (kinetic cue)
-> 1 month
Binocular disparity
difference between the retinal image of an object in each eye that results in two slightly different signals being sent to the brain
o Using disparity information to perceive depth
o The closer the object we are looking at, the greater the disparity between the two images
o Becomes functional early
Binocular fixation
fovea’s directed to same place - 3 months
Stereopsis
visual cortex computes the degree of disparity between the eyes’ differing neural signals and produces the perception of depth
o Emerges around 4 months
Monocular depth cues
-> when do they emerge?
perception cues that can be perceived by 1 eye alone
-> 6-7 months
Pictorial depth
information conveyed in a 2D image making it appear 3D, pictorial cues (shading, familiar size, overlap) - 5 to 7 months
Random-dot stereograms
technique in which infant wears special glasses
o When sensitive to disparity, they should perceive a moving rectangle and should move their eyes to follow it
o Found that infants younger than three months didn’t follow rectangle
o Children are attracted to moving stimuli but during first months, they have difficulty tracking them
o Only children older than three months can perceive depth and pictorial cues can develop even later
Familiar size
if infants were sensitive to familiar size, they would perceive object to be closer if they remembered from the familiarization period, that this shape was smaller than the other one
-> develops around 5 to 7 months
Perceiving human faces vs animal faces
develops at 9 months, “scheme” of face is made
When does perceiving object unity develop?
4-6 months
Intermodal perception
combining info from 2 or more sensory systems
Sticky fixation develops when and when does it go away
2 months, 4 months
Describe the fovea cones of infants
fat inner segments, large outer segments which leads to less visual pigment and thereby less efficient light absorption; the fat inner segments lead to bg spaces between outer segments where most of the light entering the fovea gets lost
Operant conditioning
method in which infants are given headphones and either hear mother’s or stranger’s voice depending on length of breaks during sucking *found that 2 month-olds modify
Name 2 monocular depth cues
- linear perspective
2. relative size
Relative size
monocular depth cue, when 2 or more things of a similar size appear smaller or larger depending on how far away they are
Linear perspective
monocular depth cue, when parallel lines appear to converge in the distance at vanishing point
Monocular depth cues include what category of depth cues?
pictorial depth cues (shading, size, familiar size, overlap)
Social referencing
the process of communication whereby people actively seek and use others’ perceptions and interpretations of ambiguous situations to form their own interepretations of those situations
when the the visual cliff is a dangerous situation infants use ___ only cues to modify their actions, whereas in non-threatening situations, infants additionally require ___ cues
face, vocal
Which led to lowest crossing times?
- > face only
- > voice only
- > face and voice
face and voice
Which is the most potent channel of emotional communication for infants?
- > voice
- > face
voice
Infants only use facial cues in what kind of situations?
threatening situations
