Infancy & Childhood: Development, Psychology - PDF

17 Infancy & MODULE Childhood Photo Credit: © Tony Metaxas/Photolibrary A. Prenatal Influences...

17 Infancy & MODULE Childhood Photo Credit: © Tony Metaxas/Photolibrary A. Prenatal Influences 378 Summary Test 402 B. Newborns’ Abilities 382 Critical Thinking 404 C. Emotional Development 384 Who Matters More—Parents or Peers? D. Research Focus: Temperament 386 Links to Learning 405 E. Cognitive Development 388 F. Social Development 392 Concept Review 398 G. Cultural Diversity: Gender Roles 399 PowerStudy 4.5™ Complete Module H. Application: Child Abuse 400 376  Introduction Nature-Nurture Question For the first 3 years of his life, Alex was raised in an There are now about 10,000 Romanian children Will Alex orphanage in Romania where the number of infants growing up in the United States, and nearly all of them ever learn to and children greatly exceeded the number of care- initially had serious developmental problems. One love a parent? givers. At the orphanage, Alex was given adequate researcher studying the adjustment of over 300 Roma- nutrition allowing him to develop well physically, but nian adoptees in the United States found that after the the affection, stimulation, and comfort he received were far from adequate. first year, 20% of children reached normal development, Alex, like other children living in Romanian orphanages, spent most of his 60% showed only mild problems, and the remaining days alone in a crib with almost no interaction with others. When he cried, 20% had serious cognitive, behavioral, and emotional no one came to hold or soothe him. He was never given the opportunity to problems (Fischer, 1999). The reason some Romanian bond with a caregiver. adoptees have long-term developmental problems while When Alex was 3 years old, a family living in the United States adopted others make significant improvements is complex, him. His adoptive mother described him as being friendly and engaging, involving both biological (nature) and environmental but also “self-abusive” and having a “dark side.” For (nurture) factors. instance, Alex would make himself go into a seizure by slamming his head on the floor. Developmental Psychologists He was also aggressive toward others, one The questions about why Roma- time attacking his younger sister, “beating nian adoptees vary in how they her senseless.” When asked if he wanted are affected by being raised in his adoptive mother to love him, he said to an orphanage and how they her, “I never want you to love me.” When later adjust to adoption illus- his adoptive mother asked him if he loved trate the kinds of issues and her, he replied, “No, I don’t love anybody.” questions studied by develop- After years of exhausting every treatment mental psychologists. option and still unable to feel loved by Developmental psychologists Until age 3, Alex lived in an Alex, his adoptive parents arranged for study a person’s biological, emo- orphanage where he didn’t receive affection, stimulation, or comfort. Alex to live with another family (Jarriel tional, cognitive, personal, and & Sawyer, 1997). social development across the life Children like Alex, whose emotional needs (such as forming a stable span, from infancy through late attachment with a caregiver) go unmet during infancy and early childhood, adulthood. may develop reactive attachment disorder. Later in this module, we’ll 7-year-old Alex still Reactive attachment disorder is a psychiatric illness characterized by serious explain how Alex was doing at has serious problems in his emotional problems in emotional attachments to others beginning before age 5. Some symptoms age 7 and what it means when he attachment to others. children may show include resisting comfort and affection by parents, being superfi- is finally able to say “I love you” cially engaging and overly friendly with strangers, having poor peer relationships, and to a parent. From the work of developmental psycholo- engaging in destructive behavior to themselves and to others (American Psychiatric gists, we have learned that the answer to the age-old Association, 2000; G. C. Keck & Kupecky, 1995). question of whether nature or nurture is more impor- Do all children raised in Romanian orphanages who are later adopted tant is that they are both important and their interac- have attachment problems? This question brings up an interesting issue in tion is the key to understanding how an infant develops developmental psychology referred to as the nature-nurture question. into a very complex adult with his or her own personal- The nature-nurture question asks how much nature (genetic factors) and how ity, behaviors, and goals (Pinker, 2003). much nurture (environmental factors) contributes to a person’s biological, emotional, cognitive, personal, and social development. What’s Coming Although the nature-nurture question seems like an abstract intellectual We’ll discuss how development is affected by various issue, it has very practical consequences. For example, in the United States, prenatal factors, such as alcohol, which is the leading courts have varied in how they side with biological parents (nature) over adop- known cause of mental retardation. We’ll explain the tive parents (nurture) when awarding custody of an adopted child. Tradition- amazing abilities of newborns, the early appearance of a ally, courts have favored placement with biological parents, but more recently basic emotional makeup, the surprising growth of men- some courts have begun to favor placement with adoptive parents (M. Dolan, tal abilities, the different factors that influence social 2002). For example, Dana Wakefield, a juvenile court judge, adamantly states, development, and the terrible occurrence of child abuse, “In my courtroom, they (children) stay where they’ve been nurtured. You have which affects more than a million children a year. to consider who the child feels is the psychological parents. If they have a good We’ll begin with a family whose infant son’s unusual bond in that home, I’m not about to break it” (Gibbs, 1993, p. 49). musical abilities showed how nature and nurture interact. INTRODUCTION 377 A. Prenatal Influences Nature and Nurture The reviewer for the San Francisco Examiner The amazing musical abilities of young Yehudi Was he had listened to an inspired performance certainly classify him as a prodigy. born a violin and wrote that the violinist “would one day A prodigy is a child who shows a highly unusual talent, player? be a master among masters” (Magidoff, ability, or genius at a very early age and does 1973, p. 35). not have mental retardation. A small per- At that point, the “master” was all of 5 years old and had centage of autistic children, who have some been taking lessons for only six months. His name was Yehudi degree of mental retardation, may also show Menuhin. When Yehudi was 8 years old, he made his first pro- unusual artistic or mathematical abilities; they are fessional appearance. The reviewer wrote, “This is not talent; called savants. it is genius!” (Magidoff, 1973, p. 46). Yehudi made his debut in When only 8 years Because prodigies demonstrate such unusual New York at the age of 10, and the reviewer wrote, “What built old, Yehudi made abilities so early, they are excellent examples of the his professional the world in six days is what contrived the genius of Yehudi. debut. interaction between nature (genetic influences) and He walks on the waves” (Magidoff, 1973, p. 52). nurture (learned influences). Genetic and Environmental Factors One reason Yehudi Menuhin was a prodigy and could give an inspiring violin performance at the age of 5 was the prenatal (before birth) effects of genetic influences. Prenatal influences, in the form of genetic instruc- tions, regulated the development of Yehudi’s brain and body. Parents. The father contributed half of Yehudi’s genetic instructions (23 chromosomes), and the mother contrib- uted half of the genetic instructions (23 chromosomes). The father and mother were teachers, and both had musical interests. The father had taken six violin lessons when he was a boy, but his grandfather had forbidden him to play any further. The mother had musical ability and took regular cello lessons. Through their chromo- Interaction. Yehudi Menuhin, who was universally somes, the parents passed some of their musical talents on to their three hailed as the greatest child prodigy since Mozart, developed children, Yehudi and his two younger sisters. into a legendary violin performer (Magidoff, 1973). The Daughters. The two daughters each received half of their genetic development of Yehudi’s musical talents is a perfect example instructions from their mother and half from their of how nature and nurture interact. You can see that genetic father. Both daughters, who were younger than influences (nature) played a major role in wiring his brain so Yehudi, showed early musical abilities and began that his incredible musical abilities appeared at a very early playing piano at the ages of 5 and 7. It is diffi- age, before he had a chance to learn them. You can also see cult to tell if the daughters had as much natural that environmental influences (nurture), such as being taken ability as Yehudi because in the 1930s and 1940s to concerts from age 2 on and being encouraged to practice there were few opportunities for women in professional music. As a and take lessons, encouraged Yehudi to develop the musical result, these negative environmental influences actively discouraged the talents that he had inherited from his parents. two daughters from developing their potential musical abilities. Psychologists have long recognized the importance of Son. Yehudi received half of his genetic instructions from his mother learning influences, but it is only in about the past ten years and half from his father. The unique pairing of chromosomes that psychologists have also recognized the importance of from the mother and father results in different physical and genetic factors that influence almost every aspect of behavior, Photo Credit: © UPI/Bettmann/Corbis mental traits for each of the three children. Because Yehudi including cognitive, social, emotional, and personality devel- and his two younger sisters showed great musical ability by opment (C. Baker, 2004). Today, researchers no longer focus age 5, we can assume that their early musical ability was on which is more important, nature or nurture, but rather primarily due to genetic or inherited instructions that on how nature and nurture interact to influence and regulate came from their parents’ chromosomes. However, certain environmen- our behaviors (Pinker, 2003). tal factors, such as few opportunities for women musicians, discouraged Genetic instructions from our parents can result in our the sisters from developing their talents. Different environmental fac- having a wide range of abilities. Next, we’ll explain what hap- tors, such as more opportunities for male musicians, encouraged Yehudi pens when genetic instructions are damaged—for example, if to develop his musical talents. the mother uses drugs during the prenatal period. 378 MODULE 17 INFANCY & CHILDHOOD  Prenatal Period: Three Stages You began as a single cell about the size of a grain of sand. In this Prenatal Period: How did tiny cell was the equivalent of about 300,000 pages of instructions 3. Fetal Three Stages you begin? for the development of your brain and body. This single cell marks Stage the beginning of the prenatal period. 2. Embryonic Stage The prenatal period extends from conception to birth and lasts about 266 days (around nine 1. Germinal months). It consists of three successive phases: the germinal, embryonic, and fetal stages. During Stage the prenatal period, a single cell will divide and grow to form 200 billion cells. As we examine the prenatal period, we’ll unravel one of the great puzzles of science— how a human being begins, develops, and is born. We’ll start with the germinal stage. 1 Germinal Stage 2 Embryonic Stage The germinal stage marks the beginning of our development into a During this next stage, the organism begins to develop human being. body organs. The germinal stage is the first stage of prenatal development and refers to the The embryonic stage is the second stage of the prenatal peri- two-week period following conception. od and spans the 2–8 weeks that follow conception; during this To understand how conception occurs, we need to back up a little and stage, cells divide and begin to differentiate into bone, muscle, explain ovulation. and body organs. Ovulation is the re- At about 21 days after conception, the beginnings of lease of an ovum or egg the spinal cord and eyes appear; at about 24 days, cells cell from a woman’s differentiate to form what will become part of the heart; ovaries. at about 28 days, tiny buds appear that will develop into In most cases, arms and legs; and at about 42 days, features of the face Photo Credits: left, © Pascal Goetgheluck/Photo Researchers, Inc.; right, © Petit Format/Science Source/Photo Researchers, Inc. only a single ovum is take shape. released during ovu- During this stage, the embryo is very fragile, since all lation, but sometimes of its basic organs are being formed. This is the time when two ova are released. most miscarriages occur and when most major birth If two separate ova defects occur (J. M. Nash, 2002). are released and fer- Toward the end of the embryonic stage, the organ- tilized, the result is ism has developed a number of body organs, such as the fraternal twins, who Only one of millions of sperm will fertilize this egg. heart. The can be two brothers, embryo is two sisters, or a brother and sister. Because fraternal twins come from two only about separate eggs, they are no more genetically alike than any other two chil- 4 cm long dren of the same parents. In contrast, if a single ovum splits into two parts but already after fertilization, the result is identical twins, whose genes are almost has the be- indistinguishable. ginnings of major body How does conception take place? organs and If no sperm are present, there can be no fertilization, and the ovum, limbs and together with the lining of the uterus, is sloughed off in the process called begins to menstruation. If, however, sperm have been deposited in the vagina (100– look some- 500 million sperm may be deposited with each act of intercourse), they what human make their way to the uterus and into the fallopian tubes in search of an (Cunning- ovum to be fertilized. ham et al., Conception, or fertilization, occurs if one of the millions of sperm penetrates 2009). the ovum’s outer membrane. After the ovum has been penetrated by a single sperm In the left (above photo), its outer membrane changes and becomes impenetrable to the mil- photo, you lions of remaining sperm. Embryo—about 6 weeks can see the Once the ovum has been fertilized, it is called a zygote, which is a head as the single cell that is smaller than the dot in the letter i. The zygote begins a large rounded structure at the top, and the black dot on process of repeated division and, after about a week, consists of about 150 the side of the head is the developing eye. After this sec- cells. After two weeks, it has become a mass of cells and attaches itself to ond stage of development, which is called the embryonic the wall of the uterus. Once the zygote is implanted, or attached to the stage and lasts 2–8 weeks, comes the last stage, which is wall of the uterus, the embryonic stage begins. called the fetal stage. A. P R E N ATA L INF LUE NCE S 379 A. Prenatal Influences 3 Fetal Stage The embryonic stage is fol- fetal genetic problems (Down syndrome). In What is the lowed by the fetal stage. cases where fetal genetic problems are possible, fetal stage? The fetal stage, which is the mother may wish to have her fetus tested the third stage in prenatal by a relatively safe process called amniocentesis development, begins two months after conception and (M. B. Marcus, 2000). lasts until birth. Birth defects and amniocentesis. During the At the end of the fetal stage, usually 38–42 fetal stage, a number of genetic errors can be tested weeks after conception (or roughly nine months), for by amniocentesis (AM-nee-oh-sen-TEE-sis). birth occurs and the fetus becomes a newborn. Amniocentesis, which is a medical test done During the fetal stage, the fetus develops vital between weeks 14 and 20 of pregnancy, involves organs, such as lungs, and physical characteris- inserting a long needle through the mother’s abdominal tics that are distinctively human. For example, muscles into the amniotic fluid surrounding the fetus. Figure/Text Credit: Bar graph adapted from a figure in The Developing Human: Clinically Oriented Embryology, 4th ed., by Keith L. Moore. W. B. Saunders Co., Copyright at about six months a fetus has eyes and eyelids By withdrawing and analyzing fetal cells in the fluid, that are completely formed (right photo), a fine Fetus in womb at 6 months doctors can identify a number of genetic problems. coating of hair, relatively well-developed exter- One genetic problem identified by amniocen- nal sex organs, and lungs that are beginning to function. tesis is Down syndrome (p. 288). The risk for it increases in mothers Infants born very prematurely (under six months) will have dif- who are in their forties (Cunningham et al., 2009). ficulty surviving because their lungs are not completely formed Down syndrome results from an extra 21st chromosome and causes and they have difficulty breathing. However, a six-month-old fetus abnormal physical traits (a fold of skin at the corner of each eye, a wide usually has lungs well enough developed to begin to show irregular tongue, heart defects) and abnormal brain development, resulting in breathing and, for this reason, can survive if born prematurely. degrees of mental retardation. During stage 2, the embryonic stage, and stage 3, the fetal stage, Besides Down syndrome, more than 1,000 other genetic disorders the developing organism is especially vulnerable to toxic agents can now be tested for and identified (Weil, 2006). A combination of and chemicals. To help keep out these potentially harmful agents, various relatively noninvasive screening tests completed during the the developing organism is protected by the placenta. first and second trimesters can detect Down syndrome up to 96% Placenta and teratogens. Because the fetus experiences rapid of the time. More invasive fetal DNA testing is even more definitive body growth and development of the nervous system, it is highly (Kotz, 2007b; Malone et al., 2005). As shown in the graph below, vulnerable to the effects of drugs and other harmful agents. How- birth defects can occur if something (toxin, drug, genetic malfunc- ever, the blood supply of the fetus is tion) interferes with developing structures, especially during the Umbilical Placenta cord partly protected by the placenta (left embryonic stage (J. M. Nash, 2002). figure) (Koren, 2007). Full The placenta is an organ that connects Embryonic Stage Prenatal Week Fetal Stage Term the blood supply of the mother to that of 3 4 5 6 7 8 12 16 20–36 38 the fetus. The placenta acts like a filter, allowing oxygen and nutrients to pass Central nervous system through while keeping out some toxic or Heart harmful substances. However, certain viruses, such as © 1988 by Keith L. Moore. Adapted by permission of the author. Arms HIV, and many drugs, including nico- tine, caffeine, marijuana, cocaine, and Eyes heroin, pass from the placenta into the Photo Credit: top, © Lennart Nilsson Photography Legs fetus’s blood vessels and thus can affect fetal development. These potentially dangerous agents are called External genitals teratogens. A teratogen (teh-RAT-oh-gen) is any agent that can harm a developing Ears fetus (causing deformities or brain damage). It might be a disease (such as genital herpes), a drug (such as alcohol), or another environmental agent Most sensitive period for Moderately sensitive period damaging effects for damaging effects (such as chemicals). Source: Adapted from Moore, 1988 Besides harmful chemicals, drugs, and viruses, the develop- ing fetus can also be affected by genetic problems, especially if the Next, we’ll discuss several teratogens (from the Greek word tera, parents are carriers of potentially harmful genes (Tay-Sachs) or if meaning “monster”) that can pass through the placenta and inter- the mother is in her forties, which increases the risk for certain fere with fetal growth and development. 380 MODULE 17 INFANCY & CHILDHOOD  Drugs and Prenatal Development In the womb, the fetus is protected from physical bumps by a wraparound cushion of warm fluid. The fetus is How well is the also protected from various teratogens (certain chemicals and drugs) by the filtering system of the placenta fetus protected? (described on p. 380). However, we’ll discuss several drugs, both legal and illegal, that can pass through the placenta, reach the fetus, and cause potential neurological, physiological, and psychological problems. Drug Use and Exposure to Chemicals Alcohol Caffeine. Pregnant women who use caffeine, even as little as one Heavy drinking—Fetal alcohol syndrome (FAS). In the United cup of coffee a day, are at higher risk of having an underweight States, alcohol is the leading known cause of mental retardation. baby. Babies born underweight are more likely to have health Alcohol (ethanol) is a teratogen that crosses the placenta, affects problems as adults, such as high blood pressure and diabetes the developing fetus, and can result in fetal alcohol (CARE, 2008). syndrome (S. L. Fryer et al., 2007; Riley & Cocaine plus other drugs. Pregnant women who use crack McGee, 2005). cocaine along with other drugs, such as alcohol, tobacco, or mari- Fetal alcohol syndrome, or FAS, results juana, have infants with low birth weights, poor feeding habits, from a mother drinking heavily during preg- and risks for developing other psychological problems, such as nancy, especially in the first 12 weeks. FAS low IQ scores and poor coping skills (Bendersky & Lewis, 1999). results in physical changes, such as short Research shows it is not the cocaine alone that is responsible for stature, flattened nose, and short eye open- these problems but rather the combination of drugs (D. A. Frank ings (right photo); neurological changes, such et al., 2001). as fewer brain connections within the brain Smoking and nicotine. Smoking during pregnancy increases structure; and psychological and behavioral the risk of low birth weight, preterm deliveries, and possible problems, such as hyperactivity, impulsive physical problems (Cunningham et al., 2009). In addition, infants behavior, deficits in information processing Facial features born to smoking mothers have an increased risk for developing and memory, alcohol and drug use, and poor associated with FAS attention- deficit/hyperactivity disorder (p. 27), sudden infant socialization. death syndrome (SIDS), oral clefts (birth defect of mouth and Children with fetal alcohol syndrome continue to have prob- lips), and respiratory infections (J. Braun et al., 2006; Dambro, lems into adolescence and adulthood. For example, follow-up 2006; G. M. Shaw et al., 2009). Women who smoke during preg- studies up to 21 years after the original diagnosis indicated that nancy should remember that when they inhale cigarette smoke, so FAS individuals tended to remain short, had an does their fetus. average IQ of 68 (normal is 100), were likely to Lead. Children exposed to large amounts of lead (paint, be easily distracted and to misperceive social gasoline, industry) during pregnancy have low IQ scores cues, and were at risk for developing drinking and problems in brain development. Researchers have and drug problems (Baer et al., 2003; Streiss- also found that even lower levels of lead exposure are guth et al., 1999). This means that various physi- associated with low IQ scores in children (Canfield, cal, neurological, psychological, and behavioral 2003). Also, there appears to be a link between lead problems associated with fetal alcohol syndrome exposure in the womb and during childhood and are long-lasting. attention and hyperactivity problems as well as Moderate drinking—Fetal alcohol effects criminal and antisocial behavior in adulthood, (FAE). Recently, researchers found that moder- Photo Credits: top right, © George Steinmetz; bottom, PhotoDisc, Inc. such as assaults, robbery, arson, and disorderly ate drinking (7–14 drinks per week) by pregnant conduct (J. Braun et al., 2006; Dietrich, 2003; J. P. women does not usually result in fetal alcohol syn- Wright et al., 2008). Last, childhood lead exposure drome (FAS). However, moderate drinking may is linked to a smaller brain region that is respon- result in fetal alcohol exposure (FAE), which is sible for decision making and impulse control dur- less severe than fetal alcohol syndrome but more ing adulthood, which may explain why these adults are prevalent. Researchers report children with pre- more likely to exhibit criminal and antisocial behavior natal exposure to alcohol can have growth defi- (Bellinger, 2008). ciencies and deficits in a number of cognitive tasks Air pollutants. New research provides evidence that (learning and memory), academic skills, and fine prenatal exposure to air pollutants, such as gasoline, diesel, These drugs motor speed and coordination (CDC, 2005; Watten- can affect the and coal, has a negative impact on children’s cognitive devel- developing fetus. dorf & Muenke, 2005). Researchers say there is no safe opment. Also, pregnant women exposed to high levels of air level of alcohol use during pregnancy, and therefore it pollutants are more likely to have children with low birth weights, is recommended that women who are pregnant or are planning a fetal growth deficiencies, and delays in physical development. pregnancy should not drink any alcohol (Gorman, 2006). Because it is not possible for pregnant women to completely avoid We have discussed the three stages of prenatal development, exposure to air pollutants, environmental changes in vehicles and which end with the baby’s birth. After the baby gets a pat on the power plants are important (Harder, 2006; Rich et al., 2009). backside and lets out a cry, he or she is ready to take on the world. A. P R E N ATA L INF LUE NCE S 381 B. Newborns’ Abilities Some animals, such as baby elephants (150 pounds), can walk immediately after birth. In comparison, baby Why can’t a humans (7 pounds) cannot walk because neither their leg muscles nor brain areas are well enough developed. newborn walk? However, human infants are born with a surprising number of sensory and motor abilities, such as hearing, grasping, and sucking. How these abilities develop is explained by an inherited genetic program. Genetic Developmental Program Sensory Development Conception results in a fertilized egg, which has a genetic program During the nine months of development in the womb, a genetic that is equivalent to 300,000 pages of typed instructions for devel- program is guiding the development of a number of motor and oping the body and brain. The mother and father each contribute sensory functions that are important for the newborn’s survival. 23 chromosomes so each child receives a unique genetic program. Here’s a summary of a newborn’s sensory abilities. Faces. Newborns show a preference for their mother’s face over 1. The cell body contains 3. A strand of DNA is stretched strangers’ faces in the first few days after birth. Apparently new- 23 pairs of chromosomes. out to show that it looks like a twisted ladder with borns first learn to recognize a person’s eyes, a process that occurs “chemical rungs.” through positive stimulation, such as caressing and suckling (E. M. Blass & Camp, 2001). Beginning at 4 months of age, an infant can visually distinguish his or her mother’s face from a stranger’s or an animal’s (Wingert & Brant, 2005). By 3 or 4 years of age, an infant’s visual abilities are equal to those of an adult. Hearing. One-month-old infants have very keen hearing and can discriminate small sound variations, such as the difference between bah and pah. By 6 months, infants have developed the ability to make all the 2. Each chromosome is made of a 4. “Chemical rungs” function long strand of DNA. On the 23 pairs like a chemical alphabet that sounds that are necessary to learn the lan- of chromosomes are about 30,000 writes instructions (genes) guage in which they are raised (Pascalis genes, which are pieces of DNA for development of millions of et al., 2002). that contain specific instructions. parts for your brain and body. Touch. Newborns also have a well- developed sense of touch and will Brain growth. After birth, the genetic program regulates how turn their head when lightly touched the brain develops, such as making thousands of connections on the cheek. Touch will also elicit a between neurons. For example, during the first three months of life, number of reflexes, such as grasping the most active areas of the newborn’s brain are involved in pro- and sucking. cessing sights, sounds, and touches, preparing the infant for deal- Smell and taste. Researchers ing with sensory information from the surrounding environment. found that 1-day-old infants could discriminate between a citrus odor The senses develop 1-month-old brain and a floral odor (Sullivan et al., relatively fast. Notice how 1991). Six-week-old infants can smell the neurons the difference between their mother and a stranger (Macfarlane, have made very 1975). Newborns have an inborn preference for both sweet and salt few connections. and an inborn dislike of bitter-tasting things. Depth perception. By the age of 6 months, infants have devel- oped depth perception, which was tested by observing whether they would crawl off a visual “cliff” (E. J. Gibson & Walk, 1960). 2-year-old brain A visual cliff is a glass tabletop with a checkerboard pattern over part Notice how of its surface; the remaining surface consists of clear glass with a checker- the neurons have now made board pattern several feet below, creating the illusion of a clifflike drop to many connections. the floor. Photo Credits: all, © PhotoDisc, Inc. An infant is placed on the area with the checkerboard pattern and is encouraged to creep off the cliff. Six-month-old infants hesi- In the figures above, notice that a 1-month-old brain has very tate when they reach the clear glass “dropoff,” indicating that they few neural connections, while a 2-year-old brain has many thou- have developed depth perception. sands. This enormous increase in neural connections partly Although the genetic program is largely responsible for the early explains why the weight of a baby’s brain increases from 25% to appearance of these sensory abilities, environmental stimulation, 75% of its adult weight between birth and 2 years old (Sigelman & such as parental touch and play, encourages the infant to further Rider, 2006). develop these sensory abilities (Collins et al., 2000). 382 MODULE 17 INFANCY & CHILDHOOD  Motor Development “Gloria just took her first step.” Parents are Motor development refers to the stages of motor skills that all infants Why do infants proud to note their child’s motor accom- pass through as they acquire the muscular control necessary for making crawl before plishments, which are primarily regulated coordinated movements. they walk? by a built-in genetic program. As infants Because each child has a unique genetic program, he or she will learn to crawl and walk, they change from acquire motor skills at different times (Hadders-Algra, 2002). The passive observers into very active participants in the family’s social development of early motor skills, such as sitting, crawling, and life. The first area studied by early developmental psychologists was walking, follows two general rules, called the proximodistal and motor skill development (Thelen, 1995). cephalocaudal principles. 1 The proximodistal principle states that parts closer to the center of 4 Parents often note the major milestones in the infant’s body (proximo in Latin means “near”) develop before parts their infants’ motor development, such as their farther away (distal in Latin means “far”). first time crawling or walking, because they For example, activities involving the trunk are mastered before want to know if their children are within the activities involving the arms and legs. For that reason, infants developmental norms. can roll over before they can walk or bring their arms together to Developmental norms refer to the average grasp a bottle. ages at which children perform various kinds of 2 The cephalocaudal principle states that parts of the body closer to skills or exhibit abilities or behaviors. Sitting up alone— Some examples of developmenta l the head (cephalo in Greek means “head”) develop before parts closer to average 5.5 months (range 4.5–8.0 months) norms for stages in walking accompany the feet (caudal in Greek means “tail”). the three photos. Because norms for For example, infants can lift their heads before they can con- motor development represent average ages rather than absolute trol their trunks enough to sit up, and they can sit up before they ages, parents should not be disturbed if can control their legs to crawl. In the figure below, notice the head their infant’s motor progress does not area (larger) developing before the feet area (smaller). match the norms. By the age of 2, infants have grown into toddlers who can walk up and down stairs and use their hands to hold glasses of juice, operate toys, and, of course, get into a lot Adult Child of trouble. (25 Newborn (6 years) years) 5 The reason infants develop skills and abilities at different times is that neural Crawling—average Two 10 months (range connections develop at different rates. This Photo Credits: top and center right, © Laura Dwight; bottom, © Elyse Lewin/Getty Images months 7.0–12.0 months) means that infants cannot per- (fetus) form complex cognitive, sensory, or motor tasks, such as walking, talking, and reading, until appro- priate areas of their brains develop neural connections. Head size decreases in proportion to body size. Although we have focused on the role of the genetic developmental program (nature), it’s 3 The cephalocaudal and proximodistal principles, which regu- important to remember that nature interacts late the sequence for developing early motor skills, are part of a with the environment (nurture) to encourage or dis- process known as maturation. courage the development of various motor, sensory, Maturation refers to developmental changes that are genetically or and cognitive abilities (Hadders-Algra, 2002). For biologically programmed rather than acquired through learning or life example, infants need appropriate environmental experiences. stimulation for development of their visual sys- In developing motor skills (three right photos), such as sitting tems (see things), for learning to speak (hear up alone, crawling, and walking, all infants in all parts of the parents speaking), for emotional development world go through the same developmental stages at about the same Walking alone— (get loving care), and for motor development times. However, if children are given more opportunities to prac- average (explore objects). These examples show how 12.1 months (range tice their stepping reflex earlier in life, they will begin to walk at 11.5–14.5 months) the genetic program needs and interacts with an earlier age than children who lack such opportunities (Thelen, environmental stimulation for the proper 1995). Thus, the development of early motor development is heav- development of a child’s sensory, motor, and cognitive abilities. ily influenced by maturation (genetic program) but the timing can Along with developing motor skills, an infant is also showing be partly slowed or speeded up by experience/learning (nurture). emotional changes. B. NEWBORNS’ ABILITIES 383 C. Emotional Development Definition Temperament and Emotions Becki is describing the One reason each of the sextuplets developed such a differ- How can emotional makeup of her Why did the ent emotional makeup so very early in life involves some- sextuplets be sextuplets (photo below). differences show thing called temperament. so different? “Brenna, the oldest by 30 up so early? Temperament refers to relatively stable and long-lasting indi- seconds, is the affection- vidual differences in mood and emotional behavior, which emerge ate one. Julian, the second child delivered, is ‘Mr. early in childhood because these differences are largely influenced by genetic factors. Smiley.’ Quinn, the third, is sweet and generous Researchers studied differences in infants’ temperaments by interviewing mothers and most adventurous. Claire, fourth oldest, is with 2- to 3-month-old infants and then observing these same infants repeatedly over the boss, as charming as she is tough. Ian, the the next seven years. Researchers rated each infant on nine components of tempera- fifth, is the smallest and loves music, drawing, ment, including activity level, attention span, fussiness, and mood. On the basis of and sleep. Adrian, the youngest, is the biggest these ratings, they divided infants into four categories (A. Thomas & Chess, 1977). and most gentle” (S. Reed & Breu, 1995, p. 127). Each of these 2-year-old sextuplets has a unique 1 Easy babies, who made up 40% of the sample, were happy and cheerful, had regular sleeping and eating habits, and adapted quickly emotional development (J. Bates, 2004). to new situations. 2 Slow-to-warm-up babies, who made up 15% of the sample, were more withdrawn, were moody, and tended to take longer to adapt to new situations. 3 Difficult babies, who made up 10% of the sample, were fussy, fear- ful of new situations, and more intense in their reactions. During the course of the seven-year study, difficult babies developed more serious emotional problems than the easy or slow-to-warm-up babies. 4 Photo Credits: left, © 1995 Taro Yamasaki; center, © David M. Grossman/Photo Researchers, Inc.; bottom, © PhotoDisc, Inc. No-single-category babies, who made up 35% of the sample, had a variety of Each one has a different emotional makeup. traits and could not be classified into one of the other three categories. Emotional development refers to the influence Genetic influence. Infants develop distinct temperaments very early, usually in and interaction of genetic factors, brain changes, the first 2–3 months of life, and these temperaments occur largely because of genetic cognitive factors, coping abilities, and cultural factors factors rather than learning experiences (J. Bates, 2000). For example, about 10–15% in the development of emotional behaviors, expres- of Caucasian babies inherit an inhibited or fearful temperament (e.g., show physi- sions, thoughts, and feelings (Goldsmith, 2003). ological arousal in novel situations), while about 40% inherit a fearless temperament Similar to all infants, the sextuplets initially (e.g., remain calm in novel situations) (Kagan, 2003a). showed a limited number of inherited emotional Differences in temperament are also observed in brain activ- expressions, including interest, startle, distress, ity. For example, outgoing and friendly 9-month-old babies disgust, and a neonatal smile (a half-smile that show increased activity in parts of the brain responsible for appears spontaneously for no apparent reason). positive emotions (Wingert & Brant, 2005). Also, infants with Also, similar to all infants, during the first two highly reactive or fearful temperaments at 4 months of age are years the sextuplets developed a wide range of ten times more likely to develop depression and anxiety disor- emotional expressions and feelings, including ders during adulthood than less reactive or less fearful infants. social smiling (age 4–6 weeks); anger, surprise, 10% fearful The adults who are highly reactive as infants have overdeveloped and sadness (age 3–4 months); fear (age 5–7 brain areas responsible for emotional responses, which likely months); shame and shyness (age 6–8 months); interferes with the proper functioning of these brain areas, lead- and contempt and guilt (age 24 months) (Kopp ing to mood disorders (C. Schwartz, 2008, 2009). & Neufeld, 2003). Environmental influence. About 30% of infants who began A child’s increase in emotional expressions with a fearful or fearless temperament remained that way emo- and feelings results from the interaction among tionally into adulthood, but 70% showed moderate changes in genetic, neurological (brain), cognitive, cop- temperament. One reason for changes in temperament involves ing, and cultural factors. The interaction of all environmental factors, such as family influence, poverty level, these factors explains why each of the sextu- and educational opportunities, all of which interact with and plets has a unique emotional makeup, ranging 40% fearless can change the infant’s initial temperament (Kagan 2003b). from being sweet and gentle to being charming, Thus, whether or not an infant’s genetically influenced tempera- adventurous, and tough. ment persists into adolescence and adulthood depends to a considerable extent on We’ll focus on one of the genetic factors the influence and interaction of environmental factors. involved in emotional development, which is Because an infant’s temperament influences the development of emotional behavior, called temperament. it also affects the bond or attachment between parent and child, our next topic. 384 MODULE 17 INFANCY & CHILDHOOD  Attachment For the first 3 years of his life, Psychologist John Bowlby (1969) believed that Do infants and Alex (right picture) lived in an attachment behavior evolved through a process of parents form a orphanage where he had no con- natural selection. According to his theory, attach- special bond? sistent, loving person to take care ment evolved because of its adaptive value, which of him. When he was adopted at was to give the infant a better chance of surviving age 3, he repeatedly rejected his parents’ love and he was never because the parent was close by to provide care and able to express love toward them. Living his first few years of protection. Much of the research on attachment was life without close bonding to a parent or caregiver led Alex to initiated by Mary Ainsworth (1989), who asked three have problems in attachment. Alex lived in a Romanian general questions: How does attachment occur? Attachment is a close, fundamental emotional bond that orphanage until he was Are there different kinds of attachment? What are develops between the infant and his or her parents or caregiver. adopted at age 3. the long-term effects of attachment? How Does Attachment Occur? Are There Different Kinds What Are Effects of Attachment? of Attachment? According to attachment theory, babies Because Alex never formed an attach- form an attachment to their parents Ainsworth (1979) is best known for devel- ment to a parent during infancy, he through a gradual process that begins oping a method for studying infants’ reac- will likely have difficulty forming short ly af ter birth and continues tions to being separated from, and then healthy bonds with parents or other through early childhood. As newborns, reunited with, their mothers. She used these adults in the future. As it turned out, infants have a powerful social signal, reactions to indicate the kind or quality of despite being adopted by parents who crying, which elicits care and sympa- the infants’ attachment. There are now four cared tremendously for him and tried thy. As 4- to 6-week-old infants, they different kinds of attachment, but we’ll every day to show they loved him, will begin social smiling (smiling at focus on two, which are called secure (65% Alex never bonded with them. Even at others), which will elicit joy and plea- of infants) and insecure (20% of infants) age 7, he still rejected his parents’ af- sure in t heir parents. At about 6 attachment. fection and did not trust them. Be- months, infants begin to give their par- Secure attachment is characteristic of in- cause Alex never developed a secure ents a happy greeting (smiling, holding fants who use their parent or caregiver as a safe attachment, when the time came to out their arms) when they reappear home base from which they can wander off and say good-bye to his parents and meet after a short absence. These behaviors explore their environments. his new adoptive mother, he left his contribute to children expressing their For example, when infants are placed parents without any hesitation and he needs better and understanding their in an unfamiliar room containing many immediately called the new woman parents’ emotional experiences, which interesting toys, securely attached infants “mom” and he also told her “I love ultimately help to build a good parent– tend to explore freely as long as their parent you.” child attachment (R. A. Thompson, looks on. If the parent leaves, most of the The kind of attachment formed in 1998, 2006). infants cry. On the parent’s return, securely infancy is thought to be associated As the infant develops a closer at- attached infants happily greet the caregiver with the success of future relation- tachment to her parents, she also shows and are easily soothed. In contrast, some in- ships. For example, a secure attach- more distress when her parents leave; fants show insecure attachment. ment is associated with being more this is called separation anxiety. Insecure attachment is characteristic of in- trusting, enjoying relationships more, Separation anxiety is an infant’s dis- fants who avoid or show ambivalence or resis- and dealing better with stress; an in- tress—as indicated by loud protests, cry- tance toward their parent or caregiver. secure attachment is associated with ing, and agitation—whenever the infant’s For example, insecurely attached infants being dependent and having poor parents temporarily leave. may cling and want to be held one minute social relationships and poor coping According to Ainsworth, separation but squirm and push away the next minute, skills (Burge et al., 1997; M. S. Howard anxiety is a clear sign the infant has be- displaying a lack of trust in the parent or & Medway, 2004). come attached to one or both parents. caregiver. Our relationship with our parents By the end of the first year, an infant Researchers found that an infant’s sense is also important as we get older. In usually shows a close attachment to her of trust or attachment was not affected by Module 18 (p. 413), we discuss how parents as well as to one or more other whether or how long a child was in day parenting styles inf luence the cog- family members. care. Instead, what most affected the in- nitive and emotional development However, depending on the infant’s fant’s attachment was a mother’s sensi- of teenagers. temperament (easy or difficult) and tivity, caring, and responsiveness to the The kind of attachment an infant the mother’s attitude (caring or not re- infant’s needs (NICHD, 1997). Attachments forms is partly dependent on temper- sponsive), different kinds of attachment formed in infancy may also affect one’s later ament. We’ll next discuss the kinds occur. relationships. and effects of different temperaments. C. EMOTIONAL DE VELOPMENT 385  D. Research Focus: Temperament Are Some Infants Born Fearful? We’re going to discuss a series of classic studies by Jerome Kagan (2003a) that changed How can the way we think about children’s temperaments. Kagan wanted to answer a ques- children be tion asked by many parents: Why do children raised by the same parents in the so different? same family grow up with such different emotional makeups? For example, Eric’s parents wondered why he (similar to circled child in right photo) was more shy and fearful than his two brothers, would never leave his mother’s side to play with other children, was afraid to tell a story to his grade-school class, and feared going into the swimming pool with other children (Elias, 1989). Kagan wondered if Eric was born “fearful” and if he would change as he grew up. The first problem Kagan faced was to select between two different research methods—longitudinal Why is only one child shy? and cross-sectional methods—to study developmental changes. As we discuss the advantages and dis- advantages of each method, you’ll understand why Kagan selected the longitudinal method to study temperament. Longitudinal Method Cross-Sectional Method One method researchers use to study developmental changes, such A cross-sectional method means that several groups of different- as a child’s temperament, is the longitudinal method. aged individuals are studied at the same time. A longitudinal method means that the same group of individuals is For example, in the figure below, researchers are using the studied repeatedly at many different points in time. cross-sectional method because they selected a group of 2-year- For example, as shown in the figure below, researchers first mea- olds, a group of 7-year-olds, and a group of 12-year-olds and mea- sure temperaments in a group of 2-year-old children, retest this sured their temperaments at the same time. same group again at age 7, then test them again at age 12, and so on. Advantage. The primary advantage of the cross- sectional Disadvantages. Disadvantages are that researchers must wait method is that researchers can compare any developmental differ- many years for their participants to grow older and they must deal ences, such as in temperaments, across many different age groups, with the problem of participants dropping all at the same time. This lowers the dropout rate due to relocation, out of the study due to relocation, illness, illness, or death and gives immediate results. or death. Photo Credits: top, © LWA/Dann Tardif/Getty Images; bottom © Kayoco/zefa/Corbis Age 2 7 12 Year 1989 1994 1999 Age 2 7 12 Year 1999 Advantage. A major advantage of the longitudinal method is that the same participants are used throughout the study. This Disadvantage. A major disadvantage of the cross-sectional means that researchers can track and analyze the development of approach is that it does not track the development of the same per- each participant as he or she ages and confronts new environmen- son across time but rather compares different groups at different tal conditions. This ability to track each participant across time is ages. This means that both the participants and the environmental the chief reason researchers prefer to use the longitudinal method conditions are different, which allows for more error and bias in to study developmental changes, such as changes in temperament. interpreting the results. Procedure Choosing the longitudinal method, Jerome Kagan and his environment; they also show increased physiological arousal colleagues (Kagan, 2003a; Kagan & Snidman, 1991) began (increased heart rate) and brain activity (increased response of by studying the temperaments of 4-month-olds. These amygdala—threat detector) to novel or strange situations. same infants would be retested at different ages, until they Having identified infants with two very different reached their early 20s. The initial findings were that some temperaments—inhibited/fearful and fearless—Kagan 4-month-olds were fearless while others were fearful, and his colleagues were able to study how these different whom he called inhibited children. temperaments affected emotional development by retest- Inhibited/fearful children show avoidance, anxiety, or fear ing the same participants across more than 20 years. (measured by avoiding or crying) when in a strange or novel Here’s what they found. 386 MODULE 17 INFANCY & CHILDHOOD  Results Conclusions How many were fearful/inhibited? Kagan and his colleagues observed This research answers a question several hundred 4-month-old infants and reported that about one-fourth asked by many parents: How can were classified as inhibited or highly fearful (graph below). An inhibited children raised by the same parents or highly fearful infant showed a high degree of avoidance, fretting, and in the same family have such differ- crying in novel or strange situations. A typical inhibited child stayed at ent temperaments? Part of the answer the periphery of a large group of peers, reading a book, painting at an comes from Kagan’s (2003a) series of easel, or standing in a corner quietly watching another child. One of the longitudinal studies, which showed best indicators of an inhibited child was that he or she spoke very little that infants have at least two distinct and initiated very little spontaneous conversation with unfamiliar peers temperaments—fearful/inhibited or or adults (Kagan et al., 1988; Kagan & Snidman, 1991). fearless/uninhibited. These two tem- peraments are relatively stable across Temperament at 4 months time and involve observable behav- iors (avoiding and crying), physiolog- Inhibited (fearful) 23% Being fearful ical arousal (increased heart rate), and is one kind of Uninhibited (fearless) 37% differences in the activity of the brain’s temperament. emotional detector, the amygdala. The occurrence of different temperaments in young How many were fearless/uninhibited? About one-third of the infants infants indicates the influence of genetic factors (nature). were classified as uninhibited or low-fear individuals (above graph), and the However, the finding that about 80% of the children’s remaining infants were classified in between. A typical fearless/uninhibited temperaments changed moderately indicates the influ- child was involved in group activities, was very talkative, initiated spon- ence of environmental experiences (nurture) (Pesonen et taneous interactions, engaged in conversations, often with smiling and al., 2003). laughter, and showed enthusiasm for social interactions not observed in Another interesting finding was that although children inhibited children. differed in temperament—inhibited or uninhibited—they