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CHAPTER 6 SENSATION, PERCEPTION, AND ATTENTION

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Title: CHAPTER 6 SENSATION, PERCEPTION, AND ATTENTION


1
CHAPTER 6 SENSATION, PERCEPTION, AND ATTENTION
2
Learning Objective
  • What are the views of constructivists and
    nativists on the nature-nurture issue as it
    relates to sensation and perception?

3
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

4
Learning Objectives
  • How are perceptual abilities of infants assessed?
  • What are infants visual capabilities?
  • What sorts of things do infants prefer to look
    at?

5
The Infant Assessing Sensory and Perceptual
Abilities
  • The main methods used to study infant perception
  • Habituation
  • Preferential looking
  • Evoked potentials
  • Operant conditioning

6
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

7
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

8
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

9
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

10
  • Caption Eye chart

11
  • Caption What the young eye sees

12
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

13
  • Caption Visual scanning in early infancy

14
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)

15
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

16
  • Caption An infant on the edge of a visual cliff,
    being lured to cross the deep side

17
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

18
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?

19
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

20
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

21
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

22
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

23
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

24
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?

25
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

26
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 . . .

27
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

28
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

29
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

30
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

31
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?

32
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

33
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

34
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

35
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

36
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

37
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

38
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

39
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

40
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

41
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

42
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?

43
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

44
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

45
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46
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)

47
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

48
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49
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

50
  • 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

51
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

52
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

53
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

54
  • 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

55
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)

56
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

57
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

58
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

59
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

60
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

61
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

62
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