life span ch 6

8/14/2019 Life Span CH 6

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CHAPTER 6

PERCEPTION


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Learning Objectives

What are the views ofconstructivists and

nativists on the

nature/nurture issue as

it relates to sensation

and perception?


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Nature and Nurture

Constructivists (Nurture) Perception is constructed through learning

Declines due to environmental influences

E.g., disease, loud noise etc. Nativists (Nature)

Perception does not require interpretation

Declines are universal, due to aging
http://images.google.com/imgres?imgurl=http://www.exploratorium.edu/imagery/stills/Refractive_mixing.jpg&imgrefurl=http://www.psywww.com/resource/bytopic/sens.html&h=482&w=731&sz=43&hl=en&start=1&tbnid=fLOnaPoS1rr2cM:&tbnh=93&tbnw=141&prev=/images%3Fq%3DSensation%2Band%2BPerception%26hl%3Den%26rls%3DGGIH,GGIH:2006-50,GGIH:en


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Learning Objectives

How are perceptual abilities of infants assessed? What are infants visual capabilities? What sorts of things do infants prefer to look at?
http://images.google.com/imgres?imgurl=http://www.aoa.org/images/Infants-Vision.jpg&imgrefurl=http://www.aoa.org/x4738.xml&h=158&w=200&sz=15&hl=en&start=1&tbnid=EFtRegyplAHYiM:&tbnh=82&tbnw=104&prev=/images%3Fq%3DInfants%2Bvision%26hl%3Den%26rls%3DGGIH,GGIH:2006-50,GGIH:en


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Methods of Studying Infant Perception

Habituation:Discrimination Learning Learning to be

bored

Preferential looking Duration of looking at

one of a pair

Evoked Potentials:recorded as child looks

Operant Conditioning Positive

reinforcementof onestimulus in a pair


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Vision

Present at birth Detect changes in

brightness

Visually track movingobjects

By 4 months can discriminatecolors

Visual acuity at about 8 inches Visual accommodation: 6 to 12

mo

Color vision mature at 2 to 3mo

Prefer contour, contrast, andmovement

Prefer complex over simplepatterns
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Researchers must devise special ways to assess infants perceptual abilities. Here, an experimenterand camera record how much time the infant looks at each stimulus. The visual preference test waspioneered by Robert Fantz in the early 1960s.


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In a series of studies, Cassia, Turati, and Simion (2004) showed that newborns prefer an upright face

over an upside-down one (A) and prefer a top-heavy configuration over a bottom-heavy one (B), butdo not show a preference for an upright face when paired with a top-heavy configuration.


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Vision 2

Depth perception Newborns appear to have size constancy

The visual cliff: Gibson & Walk (1960)

A crawler (7 mo) will not cross the cliff Can perceive the cliff by 2 months Fear of drop-off requires crawling

Infants as Intuitive Theorists: able to makesense of the world


10/28 An infant on the edge of a visual cliff, being lured to cross the deep side.


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Learning Objectives

What are the auditorycapabilities of infants?

What do researchers knowabout infants abilities to

perceive speech?

What are the taste and smellcapabilities of infants?

To what extent are infants

sensitive to touch,

temperature, and pain?


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Hearing and Speech

Humans can hear well before birth Newborns discriminate sounds that differ in loudness,

duration, direction, and pitch

Two- to 3-month olds distinguish phonemes Eimas (1985) Ba & Pa studies Newborns prefer female/mothers voice Lose sensitivity to sounds not needed for home

language


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Taste and Smell

Newborns can distinguishbetween sweet, bitter, and sourtastes

Show a clear preference for

sweet Facial expressions reflect taste

Cry and turn away fromunpleasant smells

Breast-fed babies recognizemothers smell

Mothers can identify theirnewborns by smell


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Learning Objectives

To what extent can infantsintegrate their sensoryexperiences?

What is an example of cross-modal perception?

What role do early experiencesplay in development ofperceptions?

What factors contribute tonormal visual perception?

What changes occur inattention throughoutchildhood?


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Integrating Sensory Information

Senses interrelated within the first month Cross-modal perception: previously seen

objects identified by touch alone

Nature: Very early perceptual abilities Nurture: Sensory system requires stimulationto develop normally

First 3-4 months=Critical/Sensitive period

Infant cataracts result in blindness Delayed understanding after cochlear

implants


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The Development of Attention

From infancy on: Attention span increases

More able to

concentrate on a task Attention becomes more

selective

Able to ignore

distractions More systematic

perceptual searches in

order to achieve goals &

solve problems


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Learning Objectives

How can hearing loss be minimized acrossthe lifespan, beginning with adolescence?

What changes occur in visual capabilities and

visual perception during adulthood? What changes occur in auditory capabilitiesand speech perception occur duringadulthood?

What changes occur in taste and smell, andin sensitivity to touch, temperature, and painduring adulthood?


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The Adult

Sensory and perceptualcapacities decline May begin in early

adulthood

Noticeable in 40s; Typical

by age 65 Gradual and minor in

normal adults

Compensation gradually

increases

Sensory threshold: point atwhich the least amount of a

stimulus can be detected

Increases with age


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Sensory/Perceptual Problems

Sensory thresholds rise withage Vision By age 70: 9/10 wear corrective

lenses 1 in 4 will have cataracts

Pupil less responsive to light

Dim lighting isproblematic

Dark and glare adaptationdifficult

Presbyopia: Middle age glasses Thickening lens = poor near

vision


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Other Visual Problems

Glaucoma: increasedeye-fluid pressure

Damages optic

nerve..

Cataracts:


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Other Visual Problems

Loss of PeripheralVision (Tunnel Vision)

Retinitis Pigmentosa(RP)

Deterioration of

light-sensitive cells


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Attention and Visual Search

Selective attentiondeclines

More easily distracted

from task

Attend to irrelevant

cues

Novel, complex tasks moredifficult

Familiar and well-

practiced skills remain


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Speech Perception

Dependent on hearingabilities

Also cognitive processes Attention, memory

Listening conditionsimportant

Background noise

problematic

Novel and complex tasksproblematic

Familiar conditions allow

use of contextual cues


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Other Senses in Older Adults

Over 70: Taste and smellthresholds increase

Many are not affected at all:

Mostly men

Affected by disease andmedications

Loss of enjoyment of food may

cause malnutrition in older

adults Less sensitive to touch and

temperature

Less sensitive to mild but notsevere pain

life span ch 6

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