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PerceptionPerception
Exam 1: 86Exam 2: CH 6-9
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DefiningSensation/Perception
Sensationtransduction (detection)changing of physical energy/externalstimuli into neural impulses.
Perception--organizing/processinginformation (interpretation)
Affected by individuals history oflearning experiences
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Nature/Nurture Issues
Imagine the world at birth Empiricists/ Constructivists --comes
from experience through learning, babies
are born with a blank slate. (nurture) Nativists--come with some built-
in/innate abilities & maturationalprograms are the driving forces in
perceptual development knowledge very similar to adults in perceptual
abilities (maturation/biology)
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Measuring Sensory/PerceptualAbilities--Preferential
Attention Presents 2 stimuli to infants &measure the length of time itspends looking at each.
Indicates that the infantdiscriminates btw the two
If he looks at one longer than theother it means:
(1) they can differentiate (2) the show preference to one
stimulus over another
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Measuring Sensory/PerceptualAbilities, Cont.
Evoked Potentials- disc on head to seewhere neural firings occur, -to what Good for testing babies for mental/neural complications
Other ways specific to sensory modality
(visual scanning) To see where an infant is looking
Operant Conditioning- shown pic of mom so that the suck at a certain rate, shows
recognition of mom if they suck more/rigorously.
Young infants not easily conditioned.
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Infant sucking video
Infants preference for human facesdue to affinity for patterned stimuliwith contour & some complexity.
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Vision Transductionretina
Inside the eye Rods- dark vision, in periphery Cones- light vision, central
Basic Abilities
Brightness/color
Visual acuity (perceive detail)
newborns, 40x worse than adult.
Infants have a more fixed focus(about 8 inches) from their face.
Caused by problems with visualaccommodations
Visual accommodation (focusing)ability to adjust the lens of the eyeby changing shape as objects
change distance
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Vision, cont.
Perceptual preferences Moderately complex patterns Contrast
Movement 2-3 mo. Prefer more normal human
faces as they develop mentalrepresentations for how it shouldlook. Color vision matures as well.
Externatility effect(movie) (up to 2 months)
Visual cicadae- littlejumps when someone reads
or w/ infants, passing linesin front of their face -ifthese cease it means theycan no longer notice thesedifferences
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Vision, cont.
Depth perception
Binocular cues
Monocular cues
Size consistencyrecognition that an
object is the same
size despite changes
in distances from the
eyes.
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Depth Perception, cont. (movie)
Gibson & Walk
Visual Cliff(classical conditioning) Slow heart rate indicates interest
or perceived difference in depth.
Intuitive Theories: comeequipped with organized sys. of
knowledge that allow them tomake sense of the world
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Hearing
Transduction--in cochlea Newborns can hear better than they see,
they can also localize sound
Sensory capabilities Wide range of pitches, loudness
Phoneme: perception (basic speech sounds)
P. Eimas (ba/pa) recognized difference 2-3 mo.
Sound localization May be reflexive at birth
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Hearing Preferences inNewborns
Cat in the Hat study: infants read to in order tosee if they would suck more to a story theyd heardbefore.
Able to recognize sound patterns, preference for
mothers voice due to constant bombardment andproximity to, more attentive to female vocals.
Prefer auditory stimulus to be relatively complex
Sound patterns--pauses in music
Loose sensitivity to sound contrasts in languagetheyre starting to learn the 1st year
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Taste
Different tastes/facial expressions Can distinguish sweet, salty, sour,
bitter (savory/fat?)
Sweet taste calming, will swallow
more amniotic fluid w/ higher sugarcontent
taste gene
Greater exposure to variety of flavor
in infancy- led to moreadventuresome eaters later on
Sensory receptors fortaste -taste buds-
located mainly on the
tongue, respond to
chemical molecules:
salt, etc.
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Taste and Smell Movie
Even newborns can differentiate btwgood and bad smells.
Have preference for human milk overformula
Olfaction receptors are located in thenasal passage
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Smell (Olfaction)
Breast-pad study: babies can tell thedifference btw mom and another female.
Underarm-pad study: could differentiate
moms B.O. on the pad & another personssmell
Caregivers recognize odors:mothers/fathers can distinguish their ownbabies scent find fecal matter of ownprogeny less offensive.
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Skin Senses
Ability to senses that detectmotion among first to develop.
Touch
Rooting reflex Habituated to touch
Develops in cephalocaudal(head to
toe) direction Temperature
Pain
Circumcision, local anesthesia
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Intermodal Perception
Different sense modalities Some ability present at birth
Cross-modal perception improves: recognizethrough one sense what is familiar throughanother
Researchers have trouble demonstrating onnewborns, dependent on task variables
btw oral and visual around 3 months of age
Impressions from different senses are fusedearly in life.
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Early Influences onPerceptual Development
Early stimulation Vision
Hearing
Sensitive period: individual is moreaffected by experiences & thus has a higherlvl of plasticity .
Fact that perceptual developmentoccurs so quickly, as if innate, is usedas an argument for Nature side.
Cultural Variation Drawings by 10-15 yr.old
children (New Guinea)
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Early Influences, cont.
Gibson--Infants active role, ltd. tobiological
Three phases
1. (birth to 4 months) - Explore immediatesurroundings :Looking, listening, mouthing
2. (5-7months) -More interested w/ objectsaround them: Voluntary grasping, closer
attention to detail, initially reflexive butimproves with gains in cortary control
3. (8 or 9 months) Exploring environment:crawling, fully examining objects
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Development of Attention--Childhood
Attention span lengthens Child once captured; older directed
toward
Due to increased myelination (insulationto sped up neural impulses)
More control of attention
Selective: deliberate concentration
Systematic
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Later life Raised sensory thresholds-- lowest pt a stimulus can
be detected. Vision
Presbyopia (thickening of lens), contracts the muscles asthey cant really adjust focus, need bifocals.
Age related Macular degeneration: damaged retinal
cells in central visual area, leading cause of blindness Cataracts, damage to the nerve causing blindness
Glaucoma, fluid pressure on the eye damages optic nerve
Hearing Presbycusis: pblms with the aging ear
Cochlear hair cells serves as auditory receptors getdamaged
Less sensitive to high pitches
Exposure to loud sounds (Tinnitus/ ringing)
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Later life, cont.
Taste, smell also less sensitive (more salt
when you get older)
Temperature
Less likely to notice changes
Pain
Weak pain--less sensitive, chronic
Bottom line--most declines are mild; older
adults usually compensate
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Critical Thinking Issue:
Should older adults be required topass driving tests more frequently?
Should family members deprive anelder of their right to drive?
Highest rate of accidents occur whenstudents learn to drive much Olderppl are now having more accidents.