perceptual development Flashcards
where is the fovea in our eye?
center of our retina
what does fovea do?
focus and facilitate sharp vision
what is bifoveal fixation?
when we fixate on an object, the image of the object is centered on the fovea of each retina.
what are the 2 steps in focusing on an image?
- getting the image onto the fovea
- processing the image
why is it difficult for babies to get an image onto the fovea? talk about:
1. converge
2. response time
3. blurred images
- babies’ eyes don’t always converge on 1 object like adults’ do. each eye sees something different.
- babies’ focusing response is slow and imprecise.
- image is focused behind retina, causing blurred images.
fill in the blanks:
the 2 types of photoreceptor cells are _____ and ______.
adult fovea contains tiny spots with 50,000 _______, which are responsible for daylight vision and ______.
infant fovea is twice as _____ and littered with other cells. cones are _________ and look different than that of adults’ (like _______). cones are less ________ and more spread out.
rod; cone
cones;color
wide; immature; stumps; concentrated
how is infant acquity measured?
- measured by smallest black and white stripes that can only be detected under high constrast
- infants prefer stripes to gray patterns thus will look at them if they can see it
true or false: infants’ visual acquity is well developed and continues developing slowly as they grow.
false. poor visual acquity but develops quickly. they see 30x worse than adults with perfect vision.
perfect eyesight is 20/20 or 6/6.
what is an infant’s eyesight?
20/600 or 6/180.
babies see from 6m away from the chart, the same thing adults do at 180m away from it.
assuming babies are looking at a ruler from 30cm away. how would they see the measurements at birth, 2 mths, 4 mths, 8 mths, 4/5 yrs?
birth - .1 inch
2 mths - .05 inch
4 mths - .025 inches
8 mths - .0125 inches
4 to 5 yrs - adult level
do babies have good color vision at birth?
no
color vision develops rapidly, much like visual acquity. how long does it take for a baby to develop adult-like color vision?
3 to 4 mths
what color combinations can babies see at birth?
grey vs red
grey vs yellow
grey vs green
green vs red
what color combination can babies see at 1 month?
grey vs blue
what color combination can babies see at 2 months?
green vs yellow
what color combination can babies see at 3 months?
red vs yellow
describe the study conducted to test infants’ perceptual categorization on whether they can detect similarities among objects. (familiarization and test trials)
quinn et al. (2001)
familiarizaton trials:
2 color photos of cats on each trial (or dogs)
6 trials, all different cats (or dogs)
test trials:
novel cat paired with novel dog
result:
- those familiarised with cats will look longer at dogs and vice versa.
- works with other animals too
- thus, babies are good at perceptual categorization
describe the study conducted to test infants’ visual recognition on whether they can recognise an object after a delay and how long their memory last. (familiarization and test trials)
fagan (1977)
familiarization trials: 2 identical faces side by side shown to babies (5-6 mths old) for 2 minutes
test trials: familiar face paired with novel face. delays: 10s, 3hrs, 1 day, 2 day, 1 wk, 2 wks
result:
- all groups looked longer at novel face
- similar results with abstract patterns instead of faces
- younger infants also succeed
- thus infants are capable of long-term visual recognition.
what are babies’ vision strengths (2) and limitations (3)?
strengths:
1. visual recognition
2. perceptual categorization
limitations:
1. visual acquity
2. color vision
3. focusing ability
what is the conclusion of the “needham et al (1998) similar vs dissimilar, move-together vs move-apart” study conducted for babies’ object perception?
4.5 mth olds can use featural info (ceg. color) to figure out how many objects are present while 3 mth olds cannot.
what is intermodal perception aka multimodal perception? give an example.
ability to integrate info from 2 or more different sensory modalities
For example, when watching a movie, intermodal perception allows us to integrate visual information with auditory cues to perceive a coherent and meaningful experience.
*the 5 sensory modalities are vision (visual), hearing (auditory), touch (tactile), taste (gustatory), and smell (olfactory).
what are the 3 conditions for auditory localisation to work?
- infant held properly
- sound not too brief
- sound not too loud or soft
what are the 2 experiments used to assess if infants can match sight to sound (intermodal perception)?
- spelke & owsley (1979)
- 3.5 mth olds in between mom video and dad video
- hears either mom/dad voice
- result: infants looked toward the face that matches the voice - kuhl & meltzoff (1984)
- 4 mth olds in between woman saying “ah” and woman saying “iii”
- hears either ah or iii
- result: look toward face that matches vowel
what is the ability to integrate info from 2 or more sensory modalities (eg. match signt to sound) called?
intermodal perception
can infants detect synchrony?
yes. unlearned.
spelke (1979): 4 mth olds shown video of different bouncing speeds on each side. hears slow or fast beat. turns towards video that matches the speed of soundtrack.
the intermodal perception of matching sight and touch is tested by meltzoff and borton (1979) on 1 mth olds. describe the study.
infants are given a pacifier to suck. then they were shown the one they sucked (nibbed), and a smooth one. they look at the one they sucked (nibbed) earlier.
what are 3 perceptions tested on infants?
- depth
- object
- intermodal (ability to integrate info from 2 or more sensory modalities)
what are the 3 types of cues adults use for depth perception?
- binocular cues
- monocular (kinetic) cues
- monocular static (pictorial) cues
what is binocular cues?
binocular disparity: difference between the images from left and right eye
what is monocular kinetic cues?
motion parallax: apparent speed and direction of objects (eg. closer objects move faster than distant ones)
what are the 3 factors of pictorial cues?
pictorial cues aka monocular static cues
- relative size (things in the distance are small)
- interposition (close things obstructs the view of (occlude) far things)
- linear perspective (lines converge in the distance)
when do the 3 cues for depth perception, namely binocular, monocular and pictorial, appear in infants?
monocular (kinetic) - present at birth
binocular - develops by 4 mths
pictorial - develops by 7 mths
what is the evidence for development of pictorial cues in infants?
yonas et al (1978)
- subjects: 5 and 7 mth olds
- baseline condition: shown real rectangular window rotated at 45 degrees, either angled towards left or ride. both age groups reach for closer side.
- test condition: trapezoidal window shown straight. covered one of infant’s eyes. 5 mth olds reach at random, 7 mth olds reach for larger side.
- thus, 7 mth olds can use pictorial cues
what is a commonly used apparatus to study depth perception?
visual cliff
describe the campos et al (1978) study on babies’ depth perception and fear of heights.
- 2 groups of infants
- 2 places where mothers stood
- results
- conclusions
1) 2 groups of infants
- beginner crawlers (7 mth old)
- experienced crawlers (9 mth old)
2) 2 places where mothers stood:
- shallow end (4-inch drop)
- deep end (40-inch drop)
3) results:
- experienced crawlers: all 15 crossed shallow side, none crossed deep side
- beginner crawlers: all 15 crossed shallow side, 10 of them crossed deep side
4) conclusions:
- beginner crawlers (7 mth olds) have depth perception but no fear of heights
- crawling experience changes babies’ understanding of depth
- infants have to learn implications of depth and fear of heights (falls/near falls or social referencing)
what study shows the effect of social referencing in depth perception of babies?
sorce et al (1985)
12 mth olds watching mom’s facial expressions
uncertain condition: 12-inch drop
- babies uncertain what to do, use social referencing (mom showed fear, did not cross. mom showed joy, proceeded to cross)
certain conditions: 40 inch vs 4 inch
- ignored social referencing for both certain conditions. 40-inch to high and 4-inch just too easy.
