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Chapter 5

PSYCH211 Chapter Notes - Chapter 5: Plantar Reflex, Depth Perception, Color Vision


Department
Psychology
Course Code
PSYCH211
Professor
Chris Burris
Chapter
5

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CHAPTER 5 BOOK
PERCEPTUAL DEVELOPMENT
THE FUNCTION OF PERCEPTION: ADAPTIVE BEHAVIOR
The function of perception is to allow us to behave sensibly in the world with respect to our survival and our
reproductive interests; the function of perception is adaptive behavior rather than knowledge
Different species are sensitive to different kinds of information in the environment; they need and can make use of
this information depending upon the adaptive problems that they have to resolve adaptive function
- Sense organs have a cost to build them as well as metabolic cost to operate them
Physical fatigue affects perception e.g.: the steep hill experiment
- Our perceptual systems are not designed to see the truth about the world but are designed to help us produce
adaptive behaviors
INSTINCT BLINDNESS
- Our inability to appreciate the complexity of our mental processes because they seem automatic and inevitable
to us
- Makes it hard to appreciate perception and hence the complexity of the adaptations underlying vision
- E.g.: you know how to use your vision but you don’t know the smallest details about it
AESTHETICS AND INTERESTS
- Our brain and visual system construct the things we see
- Things are beautiful because our visual system is designed to perceive them as beautiful
- E.g.: how a bee sees a flower is different from how humans sees it
EARLY COMPETENCIES AND INTERESTS
There many information available in the environment which are to be learned by infants.
- Orienting devices are necessary to allow the system to attend to, select, and use developmentally relevant
information
Infants interests is at social information (i.e. faces)
- Infants look at face like images longer than scrambles face images
- They prefer direct gaze over averted gaze
- Infants pay attention to the direction of one’s eyes
- Scan path: 1 month spent more time looking at the outline of the face while a two month old spent more time
looking at the internal details of the face
PRENATAL PERCEPTUAL DEVELOPMENT
VISION
- The only visual perception of a baby in the womb is of undefined lightness during the day, and complete
darkness at night
HEARING
- Ambient sounds, including the mother’s voice pass in to the uterus pretty clearly
Evidence: DeCasper’s Experiment
Infants suck artificial nipples and were motivated to hear their mother’s voice (longer rest periods)
than a strangers (shorter rest periods)
Evidence 2: They gave the mother a story to read which they will read twice per day until the baby was
born (7 months pregnant) (same sucking paradigm)
Newborns preferred the story that were read to them by their moms than hear an unfamiliar story;
they even prefer the same story read by strangers than by an unfamiliar story read by their moms
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- Infants can hear other people’s voice prenatally as well as sounds that are internal to the mother (i.e. heartbeat)
TOUCH
- Fetus can touch and feel things
- i.e. umbilical cord in utero and suck its thumb
TASTE
- EVIDENCE: pregnant women were asked to drink carrot juice 4 days a week for 3 weeks at the end of their
pregnancies. When tested months after birth, infants exposed to carrot juice preferred carrot juice than water.
SMELL
- Fetus can smell foods that the mother has ingested because amniotic fluid will smell like the foods that moms
eat
POSTNATAL PERCEPTUAL DEVELOPMENT
VISION
- Vision develops quickly over the first 6 months of an infant’s life
- At birth, neither the visual systems (occipital cortex) nor the eyes are completely developed
o ACUITY
Newborns has very underdeveloped acuity: can see at 20 feet what a normal adult can see
at 600 feet
Newborn does not see fine details but can see broad patterns because the newborn’s fovea
(central part of retina) which is responsible for fine details is not yet developed
3 months, no visual perception
6 months, can focus on objects with different distances
Acuity reaches adult level at around 5 y/o
The baby will orient to larger things than smaller things
Evidence: the infant is presented by a two side by side cards: one with black and
white bars and one that is solid gray. Showing the preference of the child on the
striped bars show the infant’s acuity.
o COLOR PERCEPTION
Adams and Courage: newborns can discriminate between green and red; green and white; red
and white; but not on subtle colors
It is because our brain involves 3 different kinds of photoreceptors and they come in different
rates
The photoreceptors that are maximally sensitive to red and green is functional early at birth; blue
mature at 3 or 4 months
3 months, color vision is quite adult like; 4 months it is adult like
o THE DEVELOPMENT OF DEPTH PERCEPTION
The development of depth to individuals is assessed through visual cliff paradigm
Visual paradigm shift study:
Infants were placed on the shallow side of the visual cliff and were observed as their mothers
stood at the far end and tried to call them over the deep side.
Results: 6 tp 14 months old hesitated and showed fear when they reached the line
Result2: some infants who have more experience with self-propelled locomotion showed
fear on the deep side and show evidence of depth perception
Active visual exploration was necessary for the development of the condition between visual
input and behavior (i.e., kittens not exposed to self-propelled locomotion showed abnormal
behavior and so on)
Children who experienced self-propelled locomotion performed better at object retrieval tasks
that required depth judgments
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