CHAPTER 6 SENSATION, PERCEPTION, AND ATTENTION

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CHAPTER 6SENSATION, PERCEPTION, AND ATTENTION
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Learning Objective

• What are the views of constructivists and
  nativists on the nature-nurture issue as it
  relates to sensation and perception?

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Nature and Nurture

• Constructivists on the side of nurture
• Argue that perceptions are constructed through
  learning
• Nativists on the side of nature
• Argue that innate capabilities and maturational
  programs drive perceptual development and that
  perception does not require interpretation

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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?

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The Infant Assessing Sensory and Perceptual
Abilities

• The main methods used to study infant perception
• Habituation
• Preferential looking
• Evoked potentials
• Operant conditioning

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The Infant Assessing Sensory and Perceptual
Abilities

• Habituation
• The process of learning to be bored with a
  stimulus
• After repeated presentation with the same visual
  stimulus, the infant becomes bored and looks away
• If a different stimulus is presented and the
  infant regains interest, researchers conclude
  that the infant has discriminated between the two
  stimuli
• Habituation can be used to test for
  discrimination of stimuli by all the senses

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The Infant Assessing Sensory and Perceptual
Abilities

• Preferential looking
• Researchers present an infant with two stimuli at
  the same time and measure the length of time the
  infant spends looking at each
• A preference for one over the other indicates
  that the infant discriminates between the two
  stimuli

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The Infant Assessing Sensory and Perceptual
Abilities

• Evoked potentials
• Researchers can assess how an infants brain
  responds to stimulation by measuring its
  electrical conductivity
• Operant conditioning
• Infants can learn to respond to a stimulus (to
  suck faster or slower or to turn the head) if
  they are reinforced for the response

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The Infant Vision

• Basic visual capacities are present at birth
• Can detect changes in brightness and can track a
  slow-moving object or picture
• Visual acuity ability to perceive detail
• Optimal at about 8 inches from the face or if
  objects are boldly patterned with sharp
  light-dark contrasts
• Visual accommodation ability to focus on
  objects at different distances
• Takes 6 months to 1 year before can see as well
  as an adult
• Color vision present at birth
• Color vision mature at 2 to 3 months

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• Caption Eye chart

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• Caption What the young eye sees

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The Infant Vision

• Infants visual preferences
• Attracted to patterns that have light-dark
  transitions, or contour
• Sharp boundaries between light and dark areas,
  such as offered by black and white objects
• Attracted to displays that are dynamic contain
  movement rather than static
• Can track a slow-moving object
• Attracted to moderately complex patterns
• Prefer clear patterns (checkerboard) to blank or
  complex stimuli
• Prefer top-heavy patterns such as the human
  face

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• Caption Visual scanning in early infancy

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The Infant Vision

• Explanation of Martin Banks and colleagues for
  infants visual preferences Young infants
  prefer to look at whatever they can see well
• Seem to actively seek the visual input they can
  see well and that will stimulate the development
  of the visual centers of their brains
• Around 2 or 3 months, a breakthrough begins to
  occur in the perception of forms
• 1-month-olds focus on the outer contours of forms
  such as faces (a persons chin, hairline, top of
  the head)
• Around 2 months, infants begin to explore the
  interiors of figures thoroughly (facial features)

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The Infant Vision

• Depth perception
• Newborns appear to have size constancy
• Recognition that an object is the same size
  despite changes in its distance from the eyes
• Classic study to examine depth perception in
  infants using the visual cliff Gibson Walk
  (1960)
• Most infants older than 6 ½ months crossed the
  shallow pattern but would not cross the deep
  or cliff pattern
• Infants can perceive the cliff by 2 months
• Most infants of crawling age (typically 7 months
  or older) clearly perceive depth and have learned
  to fear drop-offs

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• Caption An infant on the edge of a visual cliff,
  being lured to cross the deep side

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The Infant Vision

• Researchers have shown that 3-month-old infants
  can detect deviation from well-formed and
  symmetrical patterns
• 4-month-olds use common motion as an important
  cue in determining what is or is not part of the
  same object
• Use good form to perceive an objects unity or
  wholeness
• Around 6 months of age, infants can determine the
  boundaries or edges of stationary objects
• Conclusion is that infants have intuitive
  theories organized systems of knowledge that
  allow them to make sense of the world

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Learning Objectives

• What are the auditory capabilities of infants?
• What do researchers know about infants abilities
  to perceive speech?
• What are the taste and smell capabilities of
  infants?
• To what extent are infants sensitive to touch,
  temperature, and pain?

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The Infant Hearing

• Basic capacities are present at birth
• Can hear better than they can see
• Can localize sounds
• Can be startled by loud noises
• Can turn toward soft sounds
• Prefer relatively complex auditory stimuli
• Can discriminate among sounds that differ in
  loudness, duration, direction, and frequency/pitch

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The Infant Hearing

• Infants respond to human speech and prefer speech
  over non-speech sounds
• Can discriminate basic speech sounds phonemes
• The pioneering research of Eimas (1975, 1985)
  demonstrated that infants could distinguish
  similar consonants (ba and pa) and vowels (a and
  i) and between standard and rarely heard sounds

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The Infant Hearing

• Infants become increasingly sensitive to sound
  differences that are significant in their own
  language and become increasingly insensitive to
  sounds not made in their native language
• Early auditory experiences shape the formation of
  synapses in the auditory areas of the brains and
  create optimal sensitivity to the sounds in the
  native language
• Newborns attend to female voices and can
  recognize their mothers voices, even in utero

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The Infant Taste and Smell

• Newborns can distinguish sweet, bitter, and sour
  tastes
• Prefer sweet
• Facial expressions reflect taste sensations
• Olfaction sensory receptors for smell work
  well at birth
• Will turn head away from unpleasant smells
• All babies prefer the smell of human milk over
  formula, even if previously consumed formula
• At 1 to 2 weeks, breast-fed babies can recognize
  the smell of their mothers breasts or underarms

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The Infant Touch, Temperature, and Pain

• The senses of touch and motion develop before
  birth
• Sensitivity to tactile stimulation develops in a
  cephalocaudal direction
• Touch soothes a fussy baby
• Systematic massage helps premature infants to
  gain weight, be more relaxed, and develop more
  regular sleep patterns
• Newborns are sensitive to warm and cold and to
  painful stimuli
• Infants respond to pain and learn from the
  experience
• The American Academy of Pediatricians recommend
  that newborn males be given local anesthesia at
  circumcision

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Learning Objectives

• To what extent can infants integrate their
  sensory experiences?
• What is an example of cross-modal perception?
• What role do early experiences play in
  development of perceptions?
• What factors contribute to normal visual
  perception?

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The Infant Integrating Sensory Information

• At birth, sensory functions are integrated
• Newborns will look in the direction of the sound
  they hear and expect to feel objects they can see
• Integration of the senses helps babies perceive
  and respond appropriately to the objects and
  people they encounter
• Cross-modal perception is to recognize through
  one sense an object that is familiar through
  another sense
• A fragile ability that researchers are challenged
  to demonstrate in infants
• Continues to improve through childhood and
  adolescence

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The Infant Influences on Early Perceptual
Development

• Early perceptual development is evidence for
  nurture
• Basic perceptual capacities appear to be innate
  or to develop rapidly in all normal infants
• Research of Hubel and Torsten (1970) demonstrated
  the critical period for the development of
  vision in kittens blindness resulted from
  deprivation of normal visual experiences for 8
  weeks
• Among humans, early experiences affect the
  development of vision during multiple sensitive
  periods
• . . . a window of time during which an
  individual is more affected by experience, and
  thus has a higher level of plasticity than at
  other times throughout life . . .

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The Infant Influences on Early Perceptual
Development

• Sensory experience is vital in determining the
  organization of the developing brain
• The visual system requires stimulation early in
  life to develop normally
• Early visual deficits (i.e., congenital
  cataracts) can affect later visual perception
• Exposure to auditory stimulation early in life
  affects the architecture of the developing brain
  and influences auditory perception skills

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The Infant The Infants Active Role

• Gibson (1988) suggested that infants engage in
  three phases of exploratory behavior
• From birth to 4 months, infants explore their
  immediate surroundings by looking and listening
  and especially by mouthing objects and watching
  them move
• From 5 to 7 months, once infants can grasp, they
  explore objects with their hands as well as with
  their eyes
• By 8 or 9 months, infants use crawling to extend
  their explorations into the larger environment
  and carefully examine an object by fingering it,
  poking it, and watching it

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The Infant The Infants Active Role

• The combination of perception and action in
  exploratory behavior enables children to create
  sensory environments that meet their needs and
  contribute to their own development
• They are able to attend selectively to the world
  around them and choose the forms and levels of
  stimulation that suit them best

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The Infant Cultural Variations

• People from different cultures differ little in
  basic sensory capacities, such as the ability to
  discriminate degrees of brightness or loudness
• However, perceptions and interpretations of
  sensory input can vary considerably across
  cultures
• Cultural traditions affect opportunities for
  experiences, which in turn influences perceptual
  development

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Learning Objectives

• How does the development of attention occur
  during childhood?
• What characterizes the developmental disorder
  attention deficit hyperactivity disorder (ADHD)?
• How is ADHD treated?

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The Child

• Sensory and perceptual development is largely
  complete at the end of infancy and becomes more
  refined during childhood
• During childhood, sensory and perceptual
  development are largely a matter of children
  learning to use their senses more intelligently
• Perceptual development and cognitive development
  are integrated

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The Child The Development of Attention

• Perceptual development during childhood is the
  development of attention
• The focusing of perception and attention upon
  something in particular
• Infants are captured by something they react
  to environmental events
• They have an orienting system
• Children are directed toward something
• They have a focusing system that seeks out and
  maintains attention to events

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The Child Longer Attention Span

• Children have short attention spans
• In a study of sustained attention (Yendovitskaya,
  1971),
• Children ages 2 to 3 worked for an average of 18
  minutes and were easily distracted
• Children ages 5 to 6 often persisted for 1 hour
  or more
• Improvements in sustained attention occur from
  ages 5-6 to ages 8-9 as the parts of the brain
  involved with attention become further myelinated
• Beyond ages 8-9, there is little increase in the
  length of childrens sustained attention
• But become more accurate on tasks requiring
  sustained attention over the next few years

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The Child More Selective and Systematic
Attention

• Infants are not good at selective attention
  deliberately concentrating on one thing while
  ignoring something else
• Significant increase in focused attention between
  3½ and 4 years
• However, distractions will interfere with
  completion of tasks
• In a research study (Vurpillot, 1968), children
  aged 4-5 were not systematic in a visual search,
  but most children older than 6 were very
  systematic
• Improvements in visual search continue to be made
  throughout childhood and into early adulthood

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The Child Problems of Attention

• Attention deficit disorder (ADHD) is
  characterized by three symptoms
• Inattention
• Does not seem to listen, is easily distracted,
  has trouble following instructions, does not
  complete tasks, tends to be forgetful and
  unorganized
• Impulsivity
• Acts before thinking and cannot inhibit urges to
  blurt or to take a turn
• Hyperactivity
• Restless and fidgety

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The Child Problems of Attention

• Between 5-9 of school-age children meet the
  diagnostic criteria for ADHD
• Twice as many boys as girls seem to have ADHD
• Girls may be under diagnosed
• Because hyperactivity is more easily observable,
  children with predominantly hyperactivity/
• impulsivity symptoms are diagnosed around age 8
• Children with predominantly inattention symptoms
  are diagnosed two years later
• The inattentive subtype of ADHD is roughly twice
  as common as the hyperactive-impulsive subtype

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The Child Developmental Course of ADHD

• When the predominant symptom is
  hyperactivity/impulsivity, infants are very
  active and have difficult temperaments and
  irregular feeding and sleeping patterns
• Preschoolers must be evaluated in relation to
  developmental norms for activity levels
• By the grade-school years, children with ADHD are
  fidgety, restless, and inattentive to schoolwork

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The Child Developmental Course of ADHD

• An estimated 20 of ADHD children outgrow their
  overactive behavior
• Adolescents with ADHD continue to have difficulty
  concentrating on school work and often perform
  poorly in school or drop out, and behave
  impulsively
• In early adulthood, individuals with ADHD have
  lapses of concentration, procrastinate, and make
  impulsive decisions
• The more severe the ADHD and associated problems
  such as aggression in childhood, the more likely
  it is that later life outcomes will be poor

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The Child Suspected Causes of ADHD

• ADHD possibly results from deficiencies in
  executive functions controlled by the frontal
  lobes of the brain
• Difficulty in inhibiting and regulation behavior
• Low levels of dopamine and norepinephrine may be
  the cause of executive function impairments
• Genes predispose some individuals to develop ADHD
• Environmental factors may influence whether a
  genetic predisposition develops into ADHD and
  whether the individual adapts well or poorly

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The Child Treatment of ADHD

• Many children with ADHD are treated with
  stimulant drugs (i.e., Ritalin) in order to
  increase levels of dopamine and facilitate
  attention
• Controversy about possible overprescription of
  stimulants and about side effects
• Results of a multimodal treatment of attention
  deficit hyperactivity disorder study (MTA)
  medication alone was more effective than
  behavioral treatment alone or routine care in
  reducing ADHD symptoms

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Learning Objectives

• How does the capacity for attention change during
  adolescence?
• How can hearing loss be minimized across the
  lifespan, beginning with adolescence?
• What changes occur in visual capabilities and
  visual perception during adulthood?
• What changes in auditory capabilities and speech
  perception occur during adulthood?
• What changes occur in taste and smell, and in
  sensitivity to touch, temperature, and pain
  during adulthood?

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The Adolescent Attention

• The ability to sustain attention improves
  considerably between childhood and adulthood
• Result of increased myelination that speeds up
  transmission of neural impulses
• Adolescents are more efficient at ignoring
  distractions in order to concentrate
• Adolescents can divide their attention
  systematically between two tasks

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The Adolescent Hearing

• Exposure to sounds above 75 decibels can result
  in hearing loss
• Rock concerts and club music 120 to 130
  decibels
• Most common outcome is tinnitus ringing sounds
  in one or both ears
• Teens do not believe that hearing loss is a
  serious health concern for them
• Hearing protection is not cool

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The Adolescent Taste and Smell

• Changes in taste during adolescence
• Slight decline in preference for sweets and an
  increased sensitivity to sour tastes
• Adolescents are more likely to have an acquired
  taste for previously disliked or avoided foods
• Sense of smell in adolescence
• Women generally demonstrate greater sensitivity
  than men to a variety of odors (including body
  odor)

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The Adult

• Sensory and perceptual capacities decline
  gradually in normal adults
• Declines may begin in early adulthood, become
  noticeable in 40s, and are typical by age 65 and
  older
• Typically we can compensate for the deficits
• Losses take two forms
• Sensory thresholds are higher
• Sensitivity to very low levels of stimulation is
  lost
• Perceptual abilities decline in some aging adults
• Difficulty in processing or interpreting sensory
  information

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The Adult Vision

• Aging brings changes to all components of the
  visual system pupils, lens, and retina
• Pupils become smaller and do not respond as much
  when lighting conditions change
• Sharp drop in visual acuity when contrast is poor
  and light levels are low
• Dark adaptation occurs more slowly
• The lens becomes denser and less flexible
• Cannot accommodate to bring objects at different
  differences into focus
• Thickening of the lens results in presbyopia,
  decreased ability to accommodate objects close to
  the eye

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• Caption Visual acuity of older adults under
  optimal (high contrast and bright light), average
  (low contrast and bright light), and poor (low
  contrast and low light) stimulus conditions

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The Adult Vision

• The effects of age-related changes in the lens
• Visual acuity steadily declines in old age, but
  typically the implications are minor
• In one major study, three out of four older
  adults (75 years and older) had good corrected
  vision
• Women experience greater declines in visual
  acuity than men and become susceptible to falls,
  fractures, and loss of independence
• Non-corrected poor visual acuity (20/40 or worse)
  is an impairment that reduces older adults
  quality of life

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The Adult Vision

• Age-related macular degeneration (AMD) results
  from damage to retinal cells responsible for
  central vision
• Vision becomes blurry and begins to fade from the
  center of the visual field blank or dark space
  in the center of the image
• Leading cause of blindness in older adults
• Causes are unknown and there is no cure

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The Adult Vision

• Changes in the retina also lead to decreased
  visual field or loss of peripheral vision
• Loss of peripheral vision leads to tunnel vision,
  caused by retinitis pigmentosa (RP) or by
  glaucoma
• Retinitis pigmentosa is a group of hereditary
  disorders that involve gradual deterioration of
  the light-sensitive cells of the retina
• Glaucoma is caused by increased fluid pressure in
  the eye that can damage the optic nerve, cause
  loss of peripheral vision, and lead to blindness

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• Caption How a scene might be viewed by someone
  with various eye conditions A) cataracts, B)
  glaucoma, (C diabetes retinopathy, D) age-related
  macular degeneration, and E) retinitis pigmentosa

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The Adult Attention and Visual Search

• Older adults are less able to divide attention
  between two tasks or to selectively attend to
  stimuli while ignoring distractors
• Older adults have the greatest difficulties in
  processing visual information when the situation
  is novel (when they are not sure exactly what to
  look for or where to look) and when it is complex
  (there are many distractions)

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The Adult Hearing

• Among older adults, hearing impairments are three
  times as prevalent as visual impairments
• Among adults aged 65 and older, as many as 90
  have mildly impaired hearing that progressively
  worsens with age
• Most age-related hearing problems originate in
  the inner ear
• Auditory receptors and hearing-related structures
  and neurons degenerate during adulthood and
  result in presbycusis

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The Adult Hearing

• The most common form of presbycusis is loss of
  sensitivity to high-frequency or high-pitched
  sounds
• Results in difficulty hearing a childs high
  voice, the flutes in an orchestra, or
  high-frequency consonant sounds such as s, z, and
  ch
• After age 50, it also becomes difficult to hear
  lower-frequency sounds
• To be heard by an average older adult, a sound
  must be louder than the level needed by a younger
  adult
• Men show detectable hearing losses earlier in
  life than women and lose hearing sensitivity at a
  faster rate than women
• Men who work in noisy industrial conditions
  experience more hearing loss than other men

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The Adult Speech Perception

• Speech perception is dependent on the ability to
  hear and upon cognitive processes such as
  attention and memory
• To understand conversation,
• Listening conditions are important background
  noise is problematic
• Increased attentional demands (divided attention)
  are problematic
• Auditory perception is more difficult when the
  tasks are novel and complex, and the listening
  conditions are poor
• Familiar conditions allow use of contextual cues

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The Adult Aging of the Chemical Senses

• General decline in sensitivity to taste
• Older men have somewhat greater decline than
  older women
• But great variability in individual experiences
• Ability to perceive odors typically declines with
  age
• Health adults retain their sense of smell better
  than those have diseases, smoke, or take
  medications

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The Adult Touch, Temperature, and Pain

• Sensitivity for touch is gradually lost from
  middle childhood, but may not have implications
  for daily life
• Older people may be less sensitive to changes in
  temperature than younger adults
• Compared to younger adults, older adults appear
  to be less sensitive to weak levels of pain but
  are not less sensitive to stronger pain stimuli
• Older adults are more likely to experience
  chronic pain than younger adults, but are less
  likely to obtain adequate pain relief
• Treating painful conditions and providing
  effective pain relief could improve the daily
  functioning and psychological well-being of older
  adults

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The Adult in Perspective

• During adulthood, changes in sensation and
  perception of visual and auditory capacities are
  the most important and the most universal
• Senses become less sharp and are used less
  effectively
• Many sensory declines can be compensated
• Older adults with two or more sensory impairments
  are likely to experience difficulty with basic
  tasks of living
• Usually have physical or intellectual
  impairments, too, probably due to general
  declines in neural functioning that affect both
  perception and cognition
• However, most older adults, even those with
  sensory impairments, are engaged in a range of
  activities and are living full lives

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