Chapter Three

Tools for Exploring the World: Physical, Perceptual, and Motor

Development

3.1 The Newborn:Learning Objectives

• How do reflexes help newborns interact with the world?

• How do we determine whether a baby is healthy and adjusting to life outside the uterus?

• What behavioral states are common among newborns?

• What are the different features of temperament? Do they change as children grow?

The Newborn’s Reflexes

• Reflexes: the newborn is born with unlearned responses triggered by specific stimuli

– Certain reflexes have survival value

• rooting, sucking, eye blinks

– Other reflexes are developmental precursors to later voluntary motor behaviors

• stepping a precursor to walking

• Reflexes reflect the health of the child’s nervous system

Assessing the Newborn

• The five Apgar scores1. Heart rate 2. Respiration3. Muscle tone 4. Reflexes 5. Skin tone

• Each scored from 0 to 2; then summed

– Good physical condition: total of 7+– Needs special attention: total of 4-6– Life-threatening: total of 3 or less

Assessing the Newborn (cont’d)

• Neonatal Behavioral Assessment Scale (NBAS)– Includes 28 behavioral and 18 reflex items– Assesses four systems

1. Autonomic: body regulation (e.g., breathing)

2. Motor: activity level and control of body

3. State: maintaining states (e.g., alertness)

4. Social: interacting with people

The Newborn’s States

• Alert inactivity: calm, eyes open and attentive; deliberately inspecting environment

• Waking activity: open but unfocused eyes; uncoordinated motions

• Crying: cries vigorously; motion is agitated and uncoordinated

• Sleeping: eyes closed; degree of activity and quality of breathing alternate

Crying

• Basic cry– Starts softly and builds in volume and

intensity– Often seen when the child is hungry

• Mad cry– More intense and louder

• Pain cry– Starts with a loud wail, followed by a long

pause, then gasping

Sleeping

• Newborns sleep an average of 16-18 hours/day• Sleep cycles

– Newborns: 4-hour cycle; 3 hours sleep and 1 hour awake

– By 3 to 4 months: 5-to-6-hour cycle– By 6 months: sleep 10 to 12 hours at night

• REM sleep– 50% of newborn sleep– 25% by 12 months

Co-sleeping

• The practice of sleeping in the same room or bed with the child

• Much more common in cultures valuing interdependence than independence

• Research shows no evidence of increased dependence

• Co-sleeping has the advantage of avoiding elaborate sleep-time rituals

Sudden Infant Death Syndrome (SIDS)

• SIDS: sudden, inexplicable death of a healthy baby

• Risk factors– Premature birth and low birth weight– Parental smoking– Child overheating and sleeping on stomach– African-American infants (often sleep on

stomach)• Reducing risk? Sleeping on back or sides

VIDEO: Preventing SIDS

Dimensions of Temperament

• Temperament: consistent styles or patterns of infant behavior

• Number of temperament dimensions still debated (ranging from 2 to 9)

• Rothbart’s (2007) three dimensions indicate how much a child– is generally happy, active, vocal, and seeks

stimulation (surgency/extroversion)– is angry, fearful, frustrated, shy, and not easily

soothed (negative affect)– focuses attention, is not easily distracted, and can

inhibit impulses (effortful control)

Rothbart’s Dimensions of Temperament

• Three dimensions are not independent– High effortful control predicts high

surgency/extroversion, but low negative affect

• Scores during infancy predict personality in adolescents and adults

Hereditary and Environmental Contributions to Temperament

• Heredity and twin studies– Identical twins are more similar in

temperament than are fraternal twins– Heredity influences negative affect more

than other temperament dimensions

• Heredity contributes more to temperament in childhood than during infancy

Hereditary and Environmental Contributions to Temperament (cont’d)

Environment• Asian babies are less emotional, whereas

Russian babies show more fear and negative affect compared to Euro-American babies

• Parental characteristics influence temperament

– Parental responsiveness reduces infant emotionality

– Depressed mothers have more fearful infants

Heredity and environment interact• Temperament influences environment’s effect

on children– Fearful children cheated more if disciplined

with power assertion, but less if parents were nurturing and supportive

• Temperament influences how others treat the child and his or her experiences

Hereditary and Environmental Contributions to Temperament (cont’d)

Stability of Temperament

• Studies suggest that temperament tends to be somewhat stable from infancy through adulthood

• Temperament predisposes, but does not always guarantee, later personality characteristics

• Parents can nurture children to behave in ways somewhat different from their temperament

3.2 Physical Development:Learning Objectives

• How do height and weight change from birth to two years of age?

• What nutrients do young children need? How are they best provided?

• What are the consequences of malnutrition? How can it be treated?

• What are nerve cells, and how are they organized in the brain?

• How does the brain develop? When does it begin to function?

Growth of the Body

• Growth is more rapid in infancy than during any other period after birth

• Infants double their weight by three months• Infants triple their weight by one year• Average is not the same as normal

– Children of the same age can vary greatly in their heights and weights

• Height depends largely on heredity

Nutrition and Growth

• Rapid growth requires young babies to consume large amounts of calories relative to body weight

• Breast-feeding is the best way to ensure proper nourishment

• Bottle-feeding has advantages and disadvantages– All family members can enjoy intimacy with bottle– Formulas can promote proneness to allergies and

reduced immunity

Nutrition and Feeding

• New foods should be introduced one at a time

• Growth slows at two years and children become finicky eaters– Finicky eating may have survival value

• Toddlers do not know which foods are safe and stick with familiar foods

– Virtually all finicky eaters receive adequate nutrition

– New foods still introduced one at a time

Malnutrition

• World-wide about 1 in 4 children under age five are malnourished (UNICEF, 2006)

• Malnourished children develop more slowly • Malnutrition is most damaging during infancy

due to rapid growth rate• Giving malnourished children adequate diets

is challenging because they are listless, quiet, and inactive– These characteristics call less urgent

attention to the children’s needs

The Emerging Nervous System

• The brain and the rest of the nervous system consist of cells known as neurons

• Neurons consist of a soma, dendrites, the axon, and terminal buttons

• Terminal buttons release chemicals called neurotransmitters

The Brain

• The brain has 50 to 100 billion neurons• Cerebral cortex: the wrinkled surface of the

brain• Hemispheres: the two halves of the brain• Corpus callosum: the thick band of fibers

connecting the two hemispheres

The Making of the Working Brain

• The brain weighs about three-quarters of a pound at birth – about 25% of an adult brain

• At around three years of age, the child’s brain is about 80% of an adult’s brain weight

Emerging Brain Structures

• At 3 weeks after conception, the neural plate, a flat structure of cells, forms

• By 28 weeks after conception, the brain has all the neurons it will ever have

• In the 4th month of prenatal development, axons begin to form the fatty sheath, myelin– Helps speed neural transmission– Improves coordination and reaction times

• Number of synapses peaks at 12 months– Synaptic pruning: certain unnecessary synapses soon begin

to disappear

Growth of a Specialized Brain:Brain-Mapping Methods

Methods to study origins and time course of brain specialization

• Studying children with brain damage• Measuring the brain’s electrical activity

through electrodes place on scalp (EEG or electroencephalogram)

• Using magnetic fields to track brain blood flow (fMRI, functional magnetic resonance imaging)

Five General Principles of Brain Specialization

1. Specialization is early in development

Ex.: newborns’ left hemisphere generates higher electricity in response to speech

1. Specialization takes two specific forms

A. Specialized areas become more focused and less diffuse

B. Stimuli triggering brain activity become more specific than general

Five General Principles of Brain Specialization (cont’d)

3. Different brain systems specialize at different rates

Ex.: systems for sensory and perceptual processes specialize before those for higher-order processes

4. Environmental stimulation is necessary for successful specialization

A. experience-expectant growth

B. experience-dependent growth

Five General Principles of Brain Specialization (cont’d)

5. Plasticity is a benefit of the immature brain’s lack of specialization

• Atypical experiences may disrupt normal course of development (e.g., brain damage disrupting speech)

• Plasticity: brain is very flexible, allowing recovery of function, especially in young children

Brain Specialization Principle:Experience-Expectant vs.

Dependent-Growth

Experience-expectant growth• All human brains require exposure to

experiences common to all individuals (e.g., exposure to faces) to fine-tune their circuits and to have different regions specialize

Experience-dependent growth• Brain circuits and regions also are fine-tuned

according to each person’s unique experiences (e.g., learning to play the violin vs. learning to play soccer)

VIDEO: Visual-Spatial Processing

3.3 Early Motor Skills:Learning Objectives

• What are the component skills involved in learning to walk? At what age do infants master them?

• How do infants learn to coordinate the use of their hands?

Locomotion

• By 7 months, infants can sit alone• Toddling: at around 14 months, toddlers may

stand alone briefly and walk without assistance

• Dynamic systems theory– Instead of simple maturation, motor

development involves many distinct skills that are organized and reorganized over time to meet specific task demands

Posture and Balance

• Infants are “top-heavy” and easily lose their balance

• Within a few months, infants use inner ear and visual cues to adjust posture

• Infants must relearn balance each time they achieve new postures

Stepping

• Many infants move their legs alternately in a stepping-like motion as early as 6-7 months

• Infants use environmental cues to judge whether a surface is suited to walking (e.g., flat vs. bumpy)

Coordinating Skills

• Walking skills must be learned separately and then integrated with others

• Differentiation: mastery of component skills• Integration: combining components into the

sequence needed to accomplish the task• Unsupported, independent walking occurs at

about 12 to 15 months, once children have mastered and coordinated its component skills

Cultural Impact on Motor Development

• Some cultural practices encourage certain skills early and others discourage them– Ex.: parents in Africa carry children

piggyback style, which promotes walking at earlier ages than in the U.S.

– Ex.: in Paraguay, mothers constantly carry toddlers, delaying motor skills

• Despite cultural differences in average age of skill development, children acquire skills within a normal range

Fine Motor Skills

• Fine motor skills are associated with grasping, holding, and manipulating objects

• At 4 months, infants clumsily reach for objects

• By 5 months, they coordinate movement of the two hands

• By 2-3 years, children can use zippers but not buttons

• Tying shoes is a skill that develops around age 6 years

Handedness

• About 90% of children prefer to use their right hand

• Most children grasp with their right hand by age 12 months, with a clear preference seen by preschool age

• Preference is affected by heredity, but environmental factors also influences it

• Left-handedness has increased since U.S. teachers stopped urging right-handedness

3.4 Perception:Learning Objectives

• Are infants able to smell, to taste, and to experience pain?

• Can infants hear? How do they use sound to locate objects?

• How well can infants see? Can they see color and depth?

• How do infants coordinate information between different sensory modalities, such as between vision and hearing?

Coming to Know the World: Smell and Taste Perception

• Perception: brain processes receiving, selecting, modifying, and organizing sensory inputs

• Newborns have keen senses of smell and taste– Odors: they distinguish pleasant from unpleasant,

or familiar from unfamiliar (e.g., mother’s breast or perfume)

– Taste: they differentiate among salty, sour, bitter, sweet, and changes in mother’s breast milk

– Facial reactions (e.g., lip licking) show they have a “sweet tooth”

Coming to Know the World: Touch and Pain

• Babies react to touch with reflexes and other movements

• In reaction to painful stimuli, babies manifest the pain cry – a sudden, high-pitched wail – and they are not easily soothed

Coming to Know the World: Hearing

• Startle reactions suggest that infants are sensitive to sound

• Infants hear less well than adults• They best hear pitches in the range of human

speech (neither high nor low pitches) and differentiate consonants from vowels

• They prefer pleasant more than unpleasant melodies and can remember songs

• By 4 months, they recognize their own names

Coming to Know the World: Seeing

• Newborns respond to light and track moving objects with their eyes

• Visual acuity (clarity of vision) is the smallest pattern that can be distinguished dependably

• Infants at 1 month see at 20 feet what adults see at 200-400 feet

• By 1 year, infants’ visual acuity is the same as adults

Coming to Know the World: Color

• Cones: sets of neurons located along the retina at the back of the eye, each specialized to one of the three light wavelengths

• Newborns perceive few colors• 3- to 4-month-old infants can perceive colors

similarly to adults

Coming to Know the World: Depth Perception

• Visual cliff research– 6-week-olds react with interest to

differences in depth (heart rate deceleration)

– By 7 months, they show more fear than interest to the cliff’s deep end (heart rate acceleration and refusal to cross the deep side)

– Fear of depth seems to develop around the time babies can crawl

Coming to Know the World: Depth Perception (cont’d)

Seven cues adults use to infer depth

Cues Closer compared to distant objects...1. Kinetic cues … appear larger while moving

2. Visual expansion … fill more of the retina

3. Motion parallax … move faster

4. Retinal disparity … yield greater disparity

5. Sound … sound louder

Pictorial cues

6. Linear perspective … have wider parallel lines

7. Texture gradient … are coarser and distinctly textured

Coming to Know the World: Depth Perception (cont’d)

• Few-week old babies use kinetic, visual expansion, and motion parallax weeks after birth to see depth

• Infants use sound to accurately gauge depth• 4- to 6-month-old babies use retinal disparity• 7-month-old babies use linear perspective

and texture gradient to see depth

Coming to Know the World:Perceiving Objects

• Perceiving objects involves interpreting patterns of lines, textures, and colors

• Object perception is limited in newborns, but develops rapidly in the first few months

• By 4 months, infants use several cues to discern that a stimulus is an object – elements that move together– similar colors and textures– aligned edges

Perceiving Faces

• Newborns prefer to look at moving faces, suggesting an innate attraction to them

• By 4 weeks, infants track all moving stimuli, including faces and nonfaces

• Before 6 months, infants have a prototype of a face that includes both human and nonhuman faces

• Between 6 to 12 months, the prototype is fine-tuned to reflect familiar faces, which they prefer viewing

• By 7 to 8 months, infants process faces similarly to adults, as a unique arrangement of features

Integrating Sensory Information

• Infants visually recognize objects they only touched previously

• Infants soon begin to perceive the link between visual images and sounds

• Intersensory redundancy: simultaneously available multimodal sensory information (e.g., sight, sound, touch)– Infants perceive best when sensory information is

redundant– Why? Brain regions specialized for a specific

sense are not yet developed

3.5 Becoming Self-Aware:Learning Objectives

• When do children begin to realize that they exist?

• What are toddlers’ and preschoolers’ self-concepts like?

• When do preschool children begin to acquire a theory of mind?

Origins of Self-Concept

Self-awareness• Mirror test: red rouge surreptitiously rubbed

on child’s nose; child placed in front of mirror and behavior is observed– 9-month-old infants smile at the image in

the mirror but do not seem to recognize it as themselves

– By 15-24 months, infants see the image in the mirror and touch their own nose, suggesting they know the image is theirs

Origins of Self-Concept (cont’d)

• Toddlers look more at photographs of themselves than other children

• Toddlers refer to themselves by name and use personal pronouns “I” or “me”

• They use “I” in the present and in the past, showing awareness of the self’s continuity over time

• Toddlers understand ownership, indicated by use of “mine” in reference to possessions

• Preschoolers describe the self in terms of possessions, physical characteristics, preferences, and competencies

Theory of Mind (TOM)

• Theory of mind: naïve understanding of the relationship between mind and behavior

• Develops in three phases (Wellman, 1993, 2002)– Phase 1: by 2 years, aware of desires; speak of wants and likes

• Understand that people have desires and that desires cause behavior (e.g., “Ew peas; I not eat.”)

– Phase 2: by 3 years, distinguish the mental from physical world

• Use mental verbs (“think”, “believe”, “forget”), but still emphasize desires as main causes of behavior

Theory of Mind (TOM) (cont’d)

Phase 3: by 4 years, know that behavior can be based on beliefs about events, even if belief is false

• False belief tasks– Child hears story about Sally, who puts ball in the basket and leaves

– Child told the ball is moved from the basket to the box, which Sally does not know

– Child is asked, “When Sally comes back, where will Sally look for the ball ”

• 3 &1/2-year-olds: Sally will look in the box (wrong)• 4-year-olds: Sally will look in the basket (correct)

Theory of Mind (TOM) (cont’d)

How does TOM develop? • Could reflect expanding mental state language and

grammatical skills• Might be due to interactions with others, who provide

insights into people with different mental states, perspectives, feelings, intentions, moods

TOM and autism• Autism spectrum disorder (ASD)

– Echoic speech and later language acquisition– Obsessive and compulsive interest in objects– Disinterest in other people

Theory of Mind (TOM) (cont’d)

• Autism spectrum disorder (ASD) (cont’d)– Awkward social interactions with other people– Do not follow rules governing social interactions– Symptoms emerge around 18 to 24 months– Diagnosed in 1 out of 200-300 U.S. children– 80% of diagnoses are in boys– Is heritable– Atypical brain functioning; perhaps abnormal neurotransmitter

levels– Cannot be cured, but medications and a supportive environment

help a lot

Theory of Mind (TOM) (cont’d)

• ASD and TOM– Very slowly grasp false belief– Some argue they may not have a TOM

» mindblindness is a defining feature of ASD– Some attribute mindblindedness to other deficits

» cannot inhibit irrelevant actions» have problems shifting smoothly between actions

– Some attribute to a “focused” processing style» too much emphasis on perceptual details instead of the

bigger coherent picture