2LO 4-1 How do the human body and nervous system develop? LO 4-2 Does the environment affect early development?LO 4-3 What developmental tasks must infants accomplish in this period?LO 4-4 How do motor skills develop in infancy?LO 4-5 What is the role of nutrition in physical development?LO 4-6 What sensory capabilities do infants possess?LO 4-7 How sensitive are infants to pain and touch?Learning Objectives
4Physical Growth: The Rapid Advances of Infancy Infants grow at a rapid pace over the first two years of their lives (see Figure 4-1)5 months: average birth weight doubles to around 15 #1 year: weight triples to about 22 poundsEnd of 2nd year: average child weighs around four times as much as at birth
5How they grow… Continuous Figure 4-1 Height and Weight Growth Although the greatest increase in heightand weight occurs during the first year oflife, children continue to grow throughoutinfancy and toddlerhood.(Source: Cratty, 1979.)
6Physical Growth: The Rapid Advances of Infancy Not all parts of an infant's body grow at the same rateAt Birth:head accounts for one-quarter of newborn's entire bodyDuring 1st & 2nd year:rest of the body begins to catch up
7An Interesting Head Count Figure 4-2 Decreasing ProportionsAt birth, the head represents one-quarter ofthe neonate's body. By adulthood, the headis only one-eighth the size of the body. Whyis the neonate's head so large?Not all parts of an infant's body grow at the same rate.At birth the head accounts for one-quarter of the newborn's entire body size.During the first 2 years of life, the rest of the body begins to catch up.By the age of 2 the baby's head is only one-fifth of body length, and by adulthood it is only one-eighth.
8There are gender and ethnic differences in infant weight and length Girls generally are slightly shorter than boysGirls weigh slightly less than boysGender differences remain throughout childhoodAsian infants tend to be slightly smaller than NA Caucasian infantsAfrican-American infants tend to be slightly bigger than NA Caucasian infants.
9Physical Growth: The Rapid Advances of Infancy 4 Principles
10Nervous System and Brain: A Foundation of Development Neurons are the basic cells of the nervous systemNervous system comprises the brain and the nerves that extend throughout the body
11Brain Development Prenatal Neurons multiply at an amazing rate prior to birth.At some points in prenatal development, cell division creates some 250,000 additional neurons every minute.Birthbillion neuronsRelatively few neurons-neuron connectionsDuring first two yearsBillions of new connections established and become more complexAdultA single neuron is likely to have a minimum of 5,000 connections to other neurons or other body parts.
12Babies are born with many more neurons than they need Use it or lose it!Although synapses are formed throughout life, based on our changing experiences, the billions of new synapses infants form during the first two years are more numerous than necessarySynaptic pruningUnused neurons are eliminatedAllows established neurons to build more elaborate communication networks with other neuronsDevelopment of nervous system proceeds most effectively through loss of cellsMyelination“Insulation” of the wiringProtects & speeds information conductionActivity-dependent effects on myelination cannot be considered strictly a developmental event. (Fields, D.,Myelination: An Overlooked Mechanism of Synaptic Plasticity? Neuroscientist 2005)
14Coming to terms with your brain… NeuronsDendritesAxonsNeurotransmittersSynapsesLike all cells in the body, neurons have a cell body containing a nucleus.But unlike other cells, neurons have a distinctive ability: They can communicate with other cells, using a cluster of fibers called dendrites at one end.Dendrites receive messages from other cells.At their opposite end, neurons have a long extension called an axon, the part of the neuron that carries messages destined for other neurons.Neurons do not actually touch one another. Rather, they communicate with other neurons by means of chemical messengers, neurotransmitters, that travel across the small gaps, known as synapses, between neurons.
15Form and Function: Brain Growth Neurons reposition themselves with growth, becoming arranged by functionCerebral cortexupper layer of the brainhigher-order processes: thinking & reasoningbecome more developed and interconnectedSubcortical levelsLower layers of the brainregulate fundamental activities: breathing & heart ratemost fully developed at birth.
16Don't shake the baby! Shaken Baby Syndrome Brain sensitive to form forms of injuryShaking can lead to brain rotation within skullBlood vessels tear severe medical problems, long-term disabilities, and sometimes death
17Brain Development: Influences and Definitions Environmental InfluencesSensitive PeriodPlasticitya specific, but limited, time,usually early in an organism'slife, during which the organismis particularly susceptible toenvironmental influencesrelating to some particularfacet of developmentthe degree to which adeveloping structure orbehavior is modifiabledue to experience
18What do babies do all day? Integrating the bodily systems: Life cycles of infancyRhythms: repetitive, cyclical patterns of behaviorWakeSleepEatEliminateInitially like separate individuals all playing their own melody.Eventually they become like a jazz band still playing theirown riff but weaving a single, harmonious, song.
19Rhythms and States State One of major body rhythms Degree of awareness infant displays to both internal and external stimulationChange in state alters amount of stimulation required to get infant's attentionElectrical brain waves can be measured by electrocephalogram (EEG)Some of the different states that infants experience produce changes in electrical activity in the brain.These changes are reflected in different patterns of electrical brain waves, which can be measured by a device called an electroencephalogram, or EEG.Starting at three months before birth, these brain wave patterns are relatively irregular.By the time an infant reaches the age of 3 months, a more mature pattern emerges and the brain waves become more regular.
22Sleep: Perchance to Dream Major state16-17 hours daily (average); wide variationsheart rates increase and become irregular, their blood pressure rises, and they begin to breathe more rapidlyDifferent than adult sleep2 hour spurts; periods of wakefulnessCyclic patternBy 16 weeks sleep about 6 continuous hours; by 1 year sleep through night
23Cycle of Infant Behavioral States AwakeNon-alertFussingCryingDrowseDazeSleep-Wake TransitionTransition between Sleeping and WakingActiveQuietSleepActive-Quiet Transition SleepTransitional Sleep States
24REM Sleep Period of active sleep Closed eyes begin to move in a back-and-forth patternTakes up around one-half of infant sleepMay provide means for brain to stimulate itself through autostimulationIn Adults correlated with memory storage Why not in babies too?Sometimes, although not always, their closed eyes begin to move in a back-and-forth pattern, as if they were viewing an action-packed scene. This period of active sleep is similar, although not identical, to the rapid eye movement, or REM, sleep, that is found in older children and adults and is associated with dreaming.At first, this active, REM-like sleep takes up around one-half of an infant's sleep, compared with just 20 percent of an adult's sleep (see Figure 4-6). However, the quantity of active sleep quickly declines, and by the age of 6 months, amounts to just one-third of total sleep time.Some researchers think it provides a means for the brain to stimulate itself—a process called autostimulation.Stimulation of the nervous system would be particularly important in infants, who spend so much time sleeping and relatively little in alert states.
26Did you find examples in the text that suggest that cultural practices affect infants’ sleep patterns?the Kipsigis of Africa, infants sleep with their mothers and are nurse whenever they wake.They accompany their mothers during daily chores, napping while strapped to their mothers’ backsKipsigis infants do not sleep through the night until much later than babies in Western societies,the first 8 months of life, they seldom sleep longer than 3 hours at a stretch.In comparison, 8-month-old infants in the United States may sleep as long as 8 hours at a timeMuch like US breast fed kids
27SIDS: The Unanticipated Killer Sudden infant death syndrome (SIDS) is a disorder in which seemingly healthy infants die in their sleepSIDS strikes about 2,500 infants in the United States each yearAlthough it seems to occur when the normal patterns of breathing during sleep are interrupted, scientists have been unable to discover why that might happen
28Sudden Infant Death Syndrome SIDSSudden Infant Death SyndromeLeading cause of death in children under 1 year of ageBack-to-sleep guidelines (AAP)Differential riskBoysAfrican American infantsLow birthweightLow APGAR scoresMother's smokingSome brain defectsChild abuseDon’t shut the nursery door!Use your EARS!Sudden infant death syndrome (SIDS) is a disorder in which seemingly healthy infants die in their sleepSIDS strikes about 1 in 1,000 infants in the United States each year.Although it seems to occur when the normal patterns of breathing during sleep are interrupted, scientists have been unable to discover why that might happen.American Academy of Pediatrics now suggests that babies sleep on their backs rather than on their sides or stomachs—called the back-to-sleep guideline. In addition, they suggest that parents consider giving their babies a pacifier during naps and bedtime.
30Back-to-sleep is important! SIDS is found in children of every race and socioeconomic group and in children who have had no apparent health problemsSIDS strikes about 1 in 1,000 infants in the USA each year.Although it seems to occur when the normal patterns of breathing during sleep are interrupted, scientists have been unable to discover why that might happen.American Academy of Pediatrics now suggests thatbabies sleep on their backs rather than on their sides or stomachs—called the back-to-sleep guideline.parents consider giving their babies a pacifier during naps and bedtime.Back-to-sleep is important!
32Motor DevelopmentShape and proportions of newborn babies are simply not conducive to easy mobilityYoung infants lack the strength to raise large headsMovement is further impeded because limbs are short in relation to the rest of the bodyInfant bodies are mainly fat, with a limited amount of muscle; the result is a lack strength
33Motor DevelopmentBUTAt birth newborns have an extensive repertoire of behavioral possibilities brought about by innate reflexes, and their range of motor skills grows rapidly during the first two years of life
34Reflexes: Inborn Physical Skills Learned, organized involuntary responses that occur automatically in presence of certain stimuliWHAT?No, No! Reflexes are wired up unlearned responses to stimuli!
37Why do neonate reflexes come and go? Evolutionary explanations of development: gradual disappearance of reflexes to result of increase in voluntary control over behavior that occurs as infants become more able to control their muscles.It may be that reflexes form the foundation for future, more complex behaviors. As these more intricate behaviors become well learned, they encompass the earlier reflexes.Perhaps reflexes stimulate parts of the brain responsible for more complex behaviors, helping them develop.
38Intensive practice of motor behaviors May produce earlier appearance of certain motor activitiesNo evidence the activities are performed qualitatively betterEven when early gains are foundDo not produce a child w/ better motor skillsDo not produce an adult w/ better motor skills.
39Ethnic and Cultural Differences and Similarities in Neonatal Reflexes Genetically determinedUniversalCultural variations in ways displayedMoro reflexServesDiagnostic toolreflexes emerge and disappear on a regular timetabletheir absence—or presence—at a given point of infancya clue that something’s wrong in an infant's development.Social functionSurvival function
40Moro Reflex: Some differences reflect cultural and ethnic variations Moro Reflex (Startle Reflex) - stretch out the arms, flex the legs, and grab.Caucasian infants show a pronounced response.Also cry and respond in a generally agitated manner.Navajo babies react much more calmly.Arms do not flail out as much and rarely cry.
41Milestones of Motor Development Fifty percent can perform each skill at the month indicated in the figure.Timing at which each skill appears varies widely.24% walk well at 11.1 months90% by 14.9 monthsYoung infants still are able to accomplish some kinds of movement.When placed on their stomachs they wiggle their arms and legs and may try to lift their heavy heads.As their strength increases, they are able to push hard enough against the surface on which they are resting to propel their bodies in different directions.They often end up moving backwards rather than forwards, but by the age of 6 months they become rather accomplished at moving themselves in particular directions.These initial efforts are the forerunners of crawling, in which babies coordinate the motions of their arms and legs and propel themselves forward.Crawling appears typically between 8 and 10 months.Walking comes around the age of 9 months; most infants are able to walk by supporting themselves on furniture, and half of all infants can walk well by the end of their first year of life.Most are able to sit without support by the age of 6 months.
42Motor ProgressYoung infants still are able to accomplish some kinds of movement.When placed on their stomachs they wiggle their arms and legs and may try to lift their heavy heads.As their strength increases, they are able to push hard enough against the surface on which they are resting to propel their bodies in different directions.They often end up moving backwards rather than forwards, but by the age of 6 months they become rather accomplished at moving themselves in particular directions.These initial efforts are the forerunners of crawling, in which babies coordinate the motions of their arms and legs and propel themselves forward.Crawling appears typically between 8 and 10 months.Walking comes around the age of 9 months; most infants are able to walk by supporting themselves on furniture, and half of all infants can walk well by the end of their first year of life.Most are able to sit without support by the age of 6 months.
43Dynamic Systems Dynamic systems theory Describes how motor behaviors are assembledMotor skills do not develop in vacuumEach skill advances in context of other motor abilitiesAs motor skills develop, so do non-motoric skillsTheory places emphasis on child's own motivation (a cognitive state) in advancing important aspects of motor developmentMotor development in a particular sphere, such as beginning to crawl, is not just dependent on the brain initiating a “crawling program” that permits the muscles to propel the baby forward.Instead, crawling requires the coordination of muscles, perception, cognition, and motivation.Theory emphasizes how children's exploratory activities, which produce new challenges as they interact with their environment, lead them to advancements in motor skills.
44Developmental Norms Comparing Individual to Group Norms: Represent the average performance of a large sample of children of a given agePermit comparisons between a particular child's performance on a particular behavior and the average performance of the children in the norm sampleMust be interpreted with cautionBrazelton Neonatal Behavior Assessment Scale (NBAS)Brazelton Neonatal Behavior Assessment Scale (NBAS): one of the most widely used techniques to determine infants’ normative standing; measure designed to determine infants’ neurological and behavioral responses to their environment; provides a supplement to the traditional Apgar test.
45Nutrition in Infancy Fueling Motor Development Without proper nutrition, infants cannot reach physical potential and may suffer cognitive and social consequencesInfants differ in growth rates, body composition, metabolism, and activity levels
46So what is a healthy caloric allotment for infants? About 50 calories per day for each pound of weightMost infants regulate their caloric intake quite effectively on their ownIf are allowed consume as much they seem to want, and not pressured to eat more, they will be healthy
47Malnutrition Malnutrition Condition of having improper amount and balance of nutrients, produces several results, none goodMore common in children living in developing countriesSlower growth rateChronically malnourished during infancylater lower IQ scoreDo less well in schoolEffects linger even after improved diet
49Are problems of malnourishment restricted to developing countries? In the United States, some 12 million children live in poverty, which puts them at risk for malnutrition. In fact, although overall poverty rates are no worse than they were 20 years ago, the poverty rate for children under the age of 3 has increased. Some one-quarter of families who have children 2 years old and younger live in poverty.Refer students to Figure 4.10 to discuss rates for African American and Hispanic American and single-parent families.
50Undernutrition: Dietary Deficiencies Undernutrition also has long-term costs, including mild to moderate cognitive delaysUp to 25% of 1- to 5-year-old US children have diets that fall below minimum caloric intake recommended by nutritional experts1/5 of US children go to bed hungry.Do you believe these “statistics”?
51When Malnutrition Is Severe MaramusMalnutrition in first yearInfants stop growing.Attributable to severe deficiency in proteins and caloriesCauses the body to waste awayUltimately results in deathKwashiorkorFound in older childrenChild's stomach, limbs, and face swellBody struggles to make use of few available nutrients
52Nonorganic Failure to Thrive Sufficient nutritionbut are deprived of attention and stimulation.Symptomsunderdevelopment, listlessness, and apathyusually occurs by age 18 months.Reversalpossible through intensive parent trainingor removal to emotionally supportive environment.Infants receive sufficient nutrition Symptoms includeReversal
53“A fat baby is a healthy baby.” Really? Not necessarily.No clear correlation between obesity during infancy and obesity at 16 yearsBUT - some research suggests overfeeding during infancy may lead to the creation of an excess of fat cellsremain in the body throughout lifemay predispose a person to be overweight.Weight gain during infancy may relate to weight at 6Weight at 6 associated with adult obesity.
54Is Breast Best?Starting around the 1940s, the general belief among “child care experts” was that breast-feeding was an obsolete method that put children unnecessarily at risk.Bottle-feeding argument:keep track of amount of milk baby was receivingcould ensure that child got sufficient nutrients.helped mothers keep feedings to rigid schedule of one bottle every 4 hours (the recommended at that time)Mothers who breast-fed their babies could never be certain just how much milk their infants were getting.Starting around the 1940s, the general belief among child care experts was that breast-feeding was an obsolete method that put children unnecessarily at risk.Bottle-feeding argument: parents could keep track of amount of milk their baby was receiving and could ensure that child was taking in sufficient nutrients. Use of the bottle was also supposed to help mothers keep their feedings to rigid schedule of one bottle every 4 hours, the recommended procedure at that time.Mothers who breast-fed their babies could never be certain just how much milk their infants were getting.TodayBreast-feeding argument: For first 12 months of life, there is no better food for an infant than breast milk.Breast milk not only contains all the nutrients necessary for growth, but it also seems to offer some degree of immunity to a variety of childhood diseases, such as respiratory illnesses, ear infections, diarrhea, and allergies.Breast milk is more easily digested than cow's milk or formula, and it is sterile, warm, and convenient for the mother to dispense.There is even some evidence that breast milk may enhance cognitive growth, leading to high adult intelligence. Babies are more responsive to touch.For mother, may have lower rates of ovarian cancer and breast cancer prior to menopause. Hormones produced during breast-feeding help shrink uteruses of women following birth, enabling their bodies to return more quickly to a prepregnancy state. Hormones also may inhibit ovulation, reducing (but not eliminating!) chance of becoming pregnant, and thereby helping to space birth of additional children.
55Is Breast Best? Breast-feeding argument: First 12 mos no better food for an infant than breast milk.Contains all the nutrients necessary for growthOffer some immunity to a variety of childhood diseasesrespiratory illnessesear infectionsdiarrheaallergies.More easily digested than cow's milk or formulaIt’s sterile, warm, and convenient for mother to dispense.Breast milk may enhance cognitive growthLeads to high adult intelligence.Babies are more responsive to touch.
56Is Breast Best? For mother: lower rates of ovarian cancer and breast cancer prior to menopause.Hormones produced during breast-feeding help shrink uteruses of women following birthenables mom’s bodies to return more quickly to a pre-pregnancy state.Hormones also may inhibit ovulation,reducing (but not eliminating!) chance of becoming pregnantthereby helping to space birth of additional children
57So What Is the Answer? Breast milk Offers all nutrients infant needs for first 12 months of lifeIs more easily digested than alternativeProvides some immunity to variety of childhood diseasesMay enhance cognitive growthOffers significant emotional advances for mother and childNot cure-all for infant nutrition and health
58Introducing Solid Foods: When and What? Solids can be started at 6 months but are not needed until 9 to 12 months (AAFP)Introduced gradually, one at a timeCerealstrained fruitsTime of weaning varies greatly in developed and developing countries
59Learning the World Sensation is the physical stimulation of the sense organsPerceptionis the mental process of sorting out, interpreting, analyzing, and integrating stimuli from the sense organs and brain
60Visual Perception: Seeing the World Newborn's distance vision ranges from 20/200 to 20/600 distance vision is 1/10th to 1/3rd that of average adult's.By 6 months, average infant's vision is already 20/20Other visual abilities grow rapidlyBinocular visionDepth perception
61Infant Visual Preference Preferences that are present from birthGenetically preprogrammed to prefer particular kinds of stimuliPrefer to look at patterned over simpler stimuliRobert Fantz two- and three-month-old infantsDirect students to Figure 4.14.Ask: How would you use this information to explain how heredity and environmental experiences are integrated to determine infant capabilities?
62Neonate Visual Preferences curved over straight linesthree-dimensional figures to two-dimensional ones,human faces to non-faces.Such capabilities may be a reflection of the existence of highly specialized cells in the brain that react to stimuli of a particular pattern, orientation, shape, and direction of movement.Prefer their own mother's face to other faces;Distinguish between male and female faces
63Facing the WorldGenetics is not the sole determinant of infant visual preferencesA few hours after birth, infants have already learned to prefer their own mother's face to other facesSimilarly, between the ages of six and nine months, infants become more adept at distinguishingbetween the faces of humans, while they become less able to distinguish faces of members of other speciesThey also distinguish between male and female faces
64Auditory Perception: The World of Sound InfantsHear before birth and have good auditory perception after birthAre more sensitive to certain frequenciesReach adult accuracy in sound localization by age 1Can discriminate groups of different soundsReact to changes in musical key and rhythmCan discriminate many language related soundsAre born with preferences for particular sound combinations which may be shaped by prenatal exposure to mothers’ voices
65Smell and Taste in a Small World Well developed at birthHelps in recognition of mother early in lifeUsed to distinguish mother's scent (only in breast fed babies); cannot distinguish father on basis of odorTasteHave innate sweet toothShow facial disgust at bitter tastePreferences based on what mother ate during pregnancy
66Ouch! Contemporary Views on Infant Pain Today, it is widely acknowledged that infants are born with the capacity to experience painDevelopmental progression in reaction to painInfants born with capacity to experience pain; produces distressExposure to pain in infancy may lead to permanent rewiring of nervous system resulting in greater sensitivity to pain during adulthood
67The Power of TouchTouch is one of most highly developed sensory systems in a newbornEven youngest infants respond to gentle touchesSeveral of the basic reflexes present at birth require touch sensitivity to operate
68Multimodal Perception: Combining Individual Sensory Inputs New area of study in infant researchSome researchers argue that sensations are initially integrated with one another in the infantOthers maintain that infant's sensory systems are initially separate and that brain development leads to increasing integrationIt does appear that by an early age infants are able to relate what they have learned about an object through one sensory channel to what they have learned about it through anotherMultimodal approach to perception considers how information that is collected by various individual sensory systems is integrated and coordinated.Infants’ multimodal perception abilities showcase the sophisticated perceptual abilities of infants, which continue to grow throughout the period of infancy. Such perceptual growth is aided by infants’ discovery of affordances , the options that a given situation or stimulus provides.
69What are affordances? Perceptible affordances Exist where information on actions that are afforded are perceptibleThese are dependent on language, culture, context, and experience and vary for different individualsBring a small collection of found object to lecture. Have student work in groups to brainstorm about the affordances of the objects. Encourage rapid, spontaneous responses.Ask students to equate this experience with that of an infant's. What is different? What is the same?
70Becoming an Informed Consumer of Development Exercising Your Infant's Body and SensesAttempts to accelerate physical and sensory-perceptual development yield little successbutinfants need sufficient physical and sensory stimulation.
71Be Normal! Enrichment Carry a baby in different ways Let infants explore their environmentEngage in “rough-and-tumble” playLet babies touch their food and even play with itProvide toys that stimulate the senses, particularly toys that can stimulate more than one sense at a timeExpose them to varied social environmentsBe Normal!Carry a baby in different positions—in a backpack, in a frontpack, or in a football hold with the infant's head in the palm of your hand and its feet lying on your arm. This lets the infant view the world from several perspectives.Let infants explore their environment. Don't contain them too long in a barren environment. Let them crawl or wander around—after first making the environment “childproof” by removing dangerous objects.Engage in “rough-and-tumble” play. Wrestling, dancing, and rolling around on the floor—if not violent—are activities that are fun and that stimulate older infants’ motor and sensory systems.Let babies touch their food and even play with it. Infancy is too early to start teaching table manners.Provide toys that stimulate the senses, particularly toys that can stimulate more than one sense at a time. For example, brightly colored, textured toys with movable parts are enjoyable and help sharpen infants’ senses.