CHAPTER
OUTLINE
Sensation--
process by which sensory information transmitted to brain
Perception--
interpretation of sensory input
I.
Issues of nature and nurture
1. Empiricists-- all learned through experience
a. infant as tabula rasa
b. products of
nurture
c. John Locke
2. Nativists-- born
equipped with knowledge allowing us to perceive world in
meaningful way
a. abilities built
into mind
b. innate
understanding of perceptual world
c. Rene Descartes,
Immanuel Kant
3. Current debate on nature-nurture
most modern theorists take less extreme stance on
nature-nurture
II. The infant
Williams
James infant in state of “blooming, buzzing confusion”
Modern
theorist believe that infants have greater perceptual skills than anyone
suspected
A. Assessing Perceptual Abilities
1. Habituation-- learning to be bored (present
same stimulus repeatedly)
2. Preferential looking-- infants look longer at
one of two stimuli
3. Evoked potentials-- measure electrical activity
in response to stimuli
4. Operant conditioning-- learned behavior using
reinforcement
B. Vision
1. Basic capacities
a. newborn infants
can detect brightness, colors
b. newborn infants
can track slow-moving objects
c. young infants have
limited color vision due to immature receptors
d. visual acuity
(clarity of vision) poor
i.
newborn somewhere between 20/600
and 20/1200
ii.
objects beyond
8 inches are blurry
e. limited visual
accommodation-- ability of lens to change shape to bring
object into focus
2. Pattern perception
a. infants attracted
to contour-- light/dark transitions
b. infants attracted
to movement (especially at onset) and moderate
complexity
c. infants prefer
viewing objects with more information in upper field
d. preference for
whatever they can see well
e. preference for
faces changes with development
i.
at a few days infants see only
shape of head
ii.
at 2 months
infants begin to focus on interior of face
f. young infants
visually fixate while older infants can shift gaze
3. Depth perception
a. size constancy--
infant can recognize object remains same size even
though the
retinal size changes as object moves away
b. visual cliff--
device used to assess depth perception
i. 2-month olds perceive depth
ii.
fear of
drop-offs later and due to experience in crawling
4. Organizing a world of objects
a. expect common
motion-- movement of objects in same direction
b. unlearned ability
to organize visual scene into distinct objects
5. The infant as intuitive theorist
a. intuitive
knowledge-- innate equipped with organized systems of
knowledge
b. innately
understand mathematical principles
c. perceive whole forms
after a few months
C. Hearing
1. Basic capacities
a. hear better than
can see
b. can localize and
discriminate sounds
2. Perceiving speech
a. initially
sensitive to all speech sounds-- phonemes
i.
can distinguish consonant sounds
ii.
can
distinguish normal from deviant sounds
iii.
by 3 months can
recognize phoneme spoken by different
people
b. lose sensitivity
to speech sounds irrelevant to native language
related to neural connects
c. can recognize
mother's voice soon after birth
d. little newborn
recognition/preference for father’s voice
e. ability to detect
mom’s voice related to exposure to her voice while still
a fetus
D.
Taste and Smell
1. Taste buds on tongue, sense not well
understood
a. can distinguish
tastes (sweet, bitter, sour) at birth
b. like sweet
c. dislike bitter
quinine
d. food preferences
may be impacted by early tastes
infants fed sour-tasting formula preferred sour-tasting
items as
children
2. Olfaction-- (sense of smell) result of
receptors in nasal passage
a. well established
at birth
b. prefer smell of
own amniotic fluid (indicates prenatal sense of smell)
c. breast-fed infants
can recognize mother’s smell
d. mothers can
recognize their infant by smell
E. Touch, Temperature, and Pain
All
skin receptors operating in some form at birth
a. reflexive touch
apparent at birth
b. infants explore
word via tactile receptors in the mouth
c. touch can
stimulate growth in premature infants
d. newborns sensitive
to warm and cold
e. young babies
respond to pain
f. controversy over
infant’s ability to sense pain and the use of anesthesia
on infants
F. Integrating Sensory Information
1. Cross-modal perception-- recognize through
one sense something known
through another
infants have some ability to integrated multiple sensory
inputs
G. Influences on Early Perceptual Development
1. All senses are working to some extent by
birth, and most perceptual abilities emerge in the first few months
2. Early experience and the brain
a. maturation not
enough-- need early stimulation
b. normal vision
requires normal visual experience
infants born with cataracts at risk for later visual problems,
even if corrected by surgery
c. normal hearing
requires normal auditory experience
d. normal perceptual
development requires normal perceptual experience
3. The infant’s active role
a. infants seek
sensory experiences they need for development
b. Gibson’s three
phases of exploratory behavior
i.
birth to 4 months explore by
looking and listening
ii. 5 to 7 months
voluntary grasping and closer attention
iii.
8 or 9 months crawl, explore, examine
4. Cultural variation
a. little difference
in basic sensory ability
b. ability to
perceive music changes with cultural experience
c. ability to draw
the human form impacted by cultural experience
III. The
child
The
Development of Attention
1. Attention-- focusing of perception and
cognition
2. Longer attention span
3. More selective attention-- deliberate
concentration on one thing
2
to 3 1/2 years begin to show ability to focus
4. More systematic attention
better organized visual searches
IV. The adolescent
Refinement
of Attention-- Attending to Relevant and Ignoring Irrelevant Stimuli
1. Learn less about distracting information
2. Better divided attention (switching between
two stimuli)
V.
The adult
A. Losses Occur, Usually Gradual and Minor,
Beginning in Early Adulthood
1. Raised sensory thresholds-- threshold for
detection of stimuli
2. Declines in perceptual abilities
a. trouble searching
visual scene
b. perceptual
declines vary by individual and may be compensated for
B. Vision
1. Basic pattern of change
a. most people will
not lose sight with age
b. 9 out of 10 will
need corrective lenses
c. 1 in 4 will have
cataracts-- clouding of lens
2. Changes in the pupil
a. pupil becomes
smaller
b. transitions from dark to light tough
(e.g. “mood lighting” in a
restaurant)
c. slower to react
resulting in poor dark adaptation-- process of eyes
adapting to
darkness
3. Changes in the lens
a. lens yellows
b. thickening lens
leads to presbyopia
presbyopia--
difficulty seeing close objects clearly
c. distance vision
fairly stable in adulthood
d. older females show
greater visual decline than males
e. cataracts--
clouding of the lens
leading cause of blindness in old age
4. Retinal changes
a. age-related
macular degeneration-- damage to cells
responsible for
central vision
b. decrease in field
of vision (loss of peripheral vision)
c. retinitis pigmentosa-- loss of light-sensitive cells and peripheral
vision
(can show up in
childhood)
d. glaucoma--
increased fluid in eye damages optic nerve and peripheral
vision
5. Attention and visual search
a. more difficulty
processing visual information that is novel or complex
the more distractors the harder
the task
b. reduction in
efficiency of visual search skills
slower and less accurate
C. Hearing
1. Basic capacities
a. most age-related
problems occur in inner ear
b. some degeneration
of cochlear cells and neurons leading to the brain
with age
c. presbycusis--
loss of sensitivity to high frequency sounds
d. loss both
age-related and due to experience (e.g., loud noise)
2. Speech perception
a. problems under
poor listening conditions
b. more difficulty if
auditory tasks are novel and complex
D. Taste and smell
1. Trouble detecting weak taste stimulation and
odors
2. Ability to detect odors declines in old age
3. Healthy adults maintain sense of smell better
4. Ability to identify food by taste declines
with old age
loss related to loss of sense of smell and cognitive factors
5. Use of flavor enhancers and related increase
in food consumption may be a
way to improve
health in elderly
E. Touch, Temperature, and Pain
1. Detection thresholds for touch and
temperature increase
2. Differences in sensitivity to pain are small
and inconsistent
F. The Adult in Perspective
1. Declines in vision and hearing most important
and nearly universal
2. Most often vision and hearing remain
reasonably good
3. Some ability to compensate for loss, but loss
cannot be eliminated