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