6—physical development in childhood and adolescence

McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved..

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6—Physical Development in Childhood and Adolescence

• Motor Development• Sensory and Perceptual Development• Perceptual-Motor Coupling• Summary


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Motor Development• The Dynamic Systems View

– The traditional maturational view of Arnold Gesell (1934) proposed that universal milestones, such as crawling, reaching, and walking, develop through the unfolding of a genetic plan, or maturation.

– The dynamic systems theory asserts that motor development is not a passive process.

• Infants assemble motor skills for perceiving and acting; to develop motor skills, infants must perceive something in the environment that motivates them to act and use their perceptions to fine-tune their movements.


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Motor Development

• Reflexes– Built-in reactions to stimuli that govern the newborn’s

movements, which are automatic and beyond the newborn’s control.

– They allow infants to respond adaptively to their environment before they have had the opportunity to learn.


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Motor Development

• Reflexes (continued)– Rooting reflex:

• When the infant’s cheek is stroked or the side of the mouth is touched, the infant turns its head toward the side that was touched in an apparent effort to find something to suck.

– Sucking reflex: • A newborn’s built-in reaction of automatically

sucking an object placed in its mouth. The sucking reflex enables the infant to get nourishment before it has associated a nipple with food.


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Motor Development

• Reflexes (continued)– Moro reflex

• Occurs in response to a sudden, intense noise or movement. When startled, the newborn arches its back, throws its head back, and flings out its arms and legs. The newborn rapidly closes its arms and legs to the center of the body.

– Grasping reflex• When something touches the infant’s palms, the

infant responds by grasping tightly.


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Motor Development

• Reflexes (continued)– Some reflexes, such as coughing, blinking, and

yawning, persist and continue to be important throughout life.

– Other reflexes disappear several months following birth as the brain matures and voluntary control over many behaviors develops.


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Motor Development

Infant Reflexes

• Refer to Figure 6.1


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Motor Development

• Gross Motor Skills– Motor skills that involve large muscle activities, such

as moving one’s arms and walking.


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Motor Development

• Gross Motor Skills (continued)– Posture:

• A dynamic process linked with sensory information from proprioceptive cues in the skin, joints, and muscles that tell us where we are in space; from vestibular organs in the inner ear that regulate balance and equilibrium; and from vision and hearing.


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Motor Development

• Gross Motor Skills (continued)– Learning to Walk:

• To walk upright, the baby must be able to balance on one leg as the other is swung forward and to shift weight from one leg to the other.


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Motor Development

The Role of Experience in Crawling and Walking: Infants’ Judgment of Whether to Go Down a Slope



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Motor Development

Milestones in Gross Motor Development



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Motor Development

• Gross Motor Skills (continued)– Development in the Second Year

• Increased motoric skills and mobility.• First they can pull toys attached to strings, use hands

and legs to climb; then walk quickly or run stiffly, balance in a squat position, walk backward, stand and kick or throw a ball, and jump in place.

• Experts recommend against structured exercise classes for babies.

• There are cultural variations for guiding infants’ motor development.


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Motor Development

• Gross Motor Skills (continued)– Childhood

• Age 3: Use simple movements, such as hopping, jumping, and running back and forth.

• Age 4: Are more adventuresome, use jungle gyms, climb stairs with one foot on a step for some time and just beginning to come down the same way.

• Age 5: Are more adventuresome with climbing, run hard and enjoy racing.

• Middle to late childhood: Movements are smoother and more coordinated due to greater control over their bodies.


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Motor Development

•Fine Motor Skills– Motor skills that involve more finely tuned movement,

such as finger dexterity:• Infants have little control over fine motor skills at

birth; development of reaching and grasping becomes more refined during the first 2 years of life.

• Perceptual-motor coupling and experience are important for developing reaching and grasping.


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Motor Development

Infants’ Use of “Sticky Mittens” to Explore Objects



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Motor Development

• Fine Motor Control (continued)– Childhood

• Age 3: Clumsily pick up tiny objects between thumb and forefinger, build high block towers.

• Age 4: Have more precise coordination.• Age 5: Hands, arms, and fingers move together

under better command of the eye.• Middle and late childhood: Increased myelination

enhances dexterity and control; by age 7 they prefer pencils rather than crayons for printing.


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Motor Development

• Handedness– A preference for using one hand rather than the other;

right-handedness is dominant in all cultures.– Origin and development of handedness: Genetic

inheritance is likely strong.


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Motor Development

• Handedness (continued)– Handedness and Other Characteristics

• Speech processing is more likely in the left hemisphere of right-handed individuals, while left-handed individuals show more variation.

• Left-handers are more likely to have reading problems, but tend to have unusually good spatial skills.

• Left-handers are more common among mathematicians, musicians, architects, and artists.


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Review and Reflect: Learning Goal 1

• Describe how motor skills develop– Review

• What is the dynamic systems view of development?• What are some reflexes of infants?• How do gross motor skills develop?• How do fine motor skills develop?• How does handedness develop?


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– Reflect• How would you evaluate the benefits and drawbacks

of allowing an 8-year-old to play Little League baseball?


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Sensory and Perceptual Development

• What Are Sensation and Perception?– Sensation

• The product of the interaction between information and the sensory receptors—the eyes, ears, tongue, nose, and skin.

– Perception• The interpretation of what is sensed.


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• The Ecological View– We directly perceive information that exists in the

world around us.– Perception brings us into contact with the environment

in order to interact with and adapt to it.– In Gibson’s view, all objects have affordances:

opportunities for interaction offered by objects that are necessary to perform activities.


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• Studying the Newborn’s Perception– Visual Preference Method: Fantz’ (1963) method of

studying whether infants can distinguish one stimulus from another by measuring the length of time they attend to different stimuli.

– Habituation: Decreased responsiveness to a stimulus after repeated presentations.

– Dishabituation: Recovery of an habituated response after a change in stimulation.


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Fantz’s Experiment on Infants’ Visual Perception



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Habituation and Dishabituation



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• Vision– Infancy: Visual Acuity and Color Vision

• The newborn’s vision is estimated to be 20/600, by 6 months is is 20/100 or better, and by 1 year it approximates that of an adult.

• At birth, babies can distinguish between green and red, and by age 2 months all of the color-sensitive receptors (cones) of the eyes function.

• Binocular vision is acquired in the first few months.


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• Vision (continued)– Infancy: Perceiving Patterns

• Infants look at different things for different lengths of time, with preference for patterned (e.g., the human face) rather than nonpatterned displays.

• It is likely that pattern perception has an innate basis, or at least is acquired after only minimal environmental experience.


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Visual Acuity during the First Months of Life



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How 1- and 2-Month-Old Infants Scan the Human Face



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• Vision (continued)– Infancy: Perceptual Constancy

• Sensory stimulation changes but perception of the physical world remains constant.

• Size constancy: Recognition that an object remains the same even thought the retinal image of the object changes.

• Shape constancy: Recognition that an object remains the same even though its orientation to us changes.


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• Vision: Infancy (continued)– Depth Perception

• Gibson and Walk (1960) explored whether young children perceive depth using the visual cliff.

– Visual Expectations• Infants develop expectations about future events in

their world by the time they are 3 months of age.


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Examining Infants’ Depth Perception on the Visual Cliff



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• Vision: Childhood– Age 3–4: Greater efficiency at detecting boundaries

between colors.– Age 4–5: Eye muscles are developed enough to move

efficiently across a series of letters.– Although many preschoolers are farsighted, by first

grade most can focus their eyes and sustain attention on up-close objects.

– Many children experience vision problems, and 1 in every 3,000 is educationally blind.


Slide 35


• Hearing– The Fetus, Infant, and Child

• During the last 2 months of pregnancy, the fetus can hear sounds; newborns are sensitive to the sounds of human speech.

• Hearing changes in infancy involve a sound’s loudness, pitch, and localization.

• Infants cannot hear soft sounds well and are less sensitive to pitch, the perception of the frequency of a sound, than adults are.


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Hearing in the Womb



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• Hearing– Adolescence

• Although most adolescents’ hearing is excellent, listening to loud sounds for sustained periods of time is a risk factor for development hearing problems.


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• Other Senses – Touch and Pain

• Touch– Newborns respond to touch.

• Pain– Researchers have convincingly demonstrated

that newborns can feel pain.


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• Other Senses (continued)– Smell

• Newborns can differentiate odors.– Taste

• Sensitivity to taste might be present before birth.


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Newborn’s Preference for the Smell of Their Mother’s Breast Pad



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Newborns’ Facial Responses to Basic Tastes



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• Intermodal Perception– The ability to integrate information from two or more

sensory modalities, such as vision and hearing.• Crude exploratory forms of intermodal perception

exist in newborns.


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• Outline the course of sensory and perceptual development


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– Review• What are sensation and perception?• What is the ecological view of perception? What are

some research methods used to study infant perception?

• How does vision develop?• How does hearing develop?• How do touch and pain develop? How does smell

develop? How does taste develop?• What is intermodal perception and how does it

develop?


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– Reflect• How would you effectively stimulate the hearing of

a 1-year-old child?


Slide 46

Perceptual-Motor Coupling

• Perceptual-Motor Coupling– Perceptual and motor development do not occur in

isolation from one another; instead, they are coupled.– Babies coordinate their movements with perceptual

information to learn how to maintain balance, reach for objects in place, and move across various surfaces.

– Action educates perception; e.g., locomotion in the environment teaches babies about how objects and people look from different perspectives, or whether surfaces will support their weight.


Slide 47

Review and Reflect:Learning Goal 3

• Discuss the connection of perception and action– Review

• How are perception and motor actions coupled in development?

– Reflect• Describe two examples not given in the text in

which perception guides action. Then describe two examples not given in the text in which action guides perception.


Slide 48

Summary• Dynamic systems theory describes the development of

motor skills as the assembling of behaviors for perceiving and acting.

• Reflexes are automatic movements that govern the newborn’s behavior; some reflexes persist throughout life, others disappear after a few months.

• Gross motor skills involving large motor activities improve dramatically in the childhood years; the development of posture and learning to walk illustrate the complexity of motor development and the importance of perceptual-motor coupling.


Slide 49

Summary

• Fine motor skills involve finely tuned movements, such as finger dexterity; they continue to develop through the childhood years.

• Handedness likely has a genetic link and typically affects where speech is processed. Left-handers tend to have unusually good visuospatial skills and are disproportionately represented among mathematicians, musicians, architects, and artists.


Slide 50

Summary

• Sensation occurs when information interacts with the sensory receptors—the eyes, ears, tongue, nose, and skin.

• Perception is the interpretation of what is sensed.• In the ecological view, perception functions to

bring organisms in contact with the environment and increase adaptation.

• Researchers, such as Fantz, have developed many methods to assess infant perception.


Slide 51

Summary

• Visual acuity increases dramatically in the first year of life.• Newborns can see and can distinguish green and red, and

by 2 months all color-sensitive receptors (cones) function in adult-like ways; infants systematically scan human faces; by 3 months, they show size and shape constancy; and by 6 months they have depth perception.

• Many children experience vision problems, and 1 in every 3,000 is educationally blind.

• The fetus can hear several weeks before birth.• Newborns can respond to touch and feel pain.


Slide 52

Summary

• By 2 months, infants have intermodal perception, the ability to relate and integrate information about two or more sensory modalities, such as vision and hearing.

• Perception and action are coupled: Individuals perceive in order to move and move in order to perceive.

6—physical development in childhood and adolescence

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