Developmental psychology is defined as the scientific study of change throughout the lifespan. As the definition implies, developmental psychology is a vast scientific discipline that can examine virtually any phenomenon from a developmental perspective. We will see that change can be studied across various domains and developmental periods. It is evident that development can be studied because there is an order to God’s universe, and He has designed us to develop in a predictable sequence over time. Although there are variations from person to person, all people are born, experience growth and decline, and eventually die. DOMAINS OF DEVELOPMENT It is common for developmental psychologists to organize development into three broad domains: Physical development, cognitive development, and socioemotional development. Physical development includes growth during the early part of life, such as an embryo’s development of organs or puberty during adolescence. It also consists of the physical declines we experience with aging. Genetics, motor skills, sexual maturation, hormonal changes, and brain chemistry are just a few changes within this category. Cognitive development has to do with our thinking and intellectual abilities. It includes language development, moral reasoning, and abstract and concrete thought. It also involves cognitive decline, dementia, and Alzheimer’s disease. Socioemotional development considers our feelings and relationships. Attachment, temperament, interpersonal skills, identity, self-esteem, and even social media are just a few topics considered. Finally, we will end the chapter by briefly looking at spiritual development , which concerns religious and spiritual beliefs and experiences. It includes faith development and meaning-making and studying how spirituality and religiousness influence individual factors like identity, attitudes, motivation, or coping. Although it can be helpful to organize development into distinct categories, change is a complex process that involves the interrelationship of all the domains. It also happens over time and is a lifelong process. Consequently, it can be challenging to organize development in multiple domains across the lifespan in a logical and understandable way. Usually, human development is organized by domain or by developmental periods. We have arranged this chapter by domain in the following order: physical development, cognitive development, socioemotional development, and spiritual development. As we explore each domain, we will look at development during major developmental periods. Below we have divided the lifespan into periods by approximate age ranges. PERIODS OF DEVELOPMENT: FROM THE WOMB TO THE TOMB Recall that development occurs throughout the entire lifespan. However, a common misconception that is held today is that developmental psychologists only study infants and children. Although this may have been the case many years ago, the 20thcentury saw research expand beyond childhood. Technological advances have allowed us to study prenatal development in ways that were not possible until recently. Furthermore, with people living longer, studies during late adulthood have become much more common, and there is a rapidly growing body of literature on aging. Childhood and adolescence continue to be significant focuses of developmental research. In fact, the recent COVID-19 pandemic opened critical new areas of study in childhood and adolescent development. For years to come, scientists will be studying the effects of isolation and quarantines, social distancing, mask mandates, vaccines, and potential long-term physical health consequences of contracting the virus. Likewise, technology continues to change the way we engage with the world. Developmental research is being conducted from childhood through adulthood on the influence of social media, virtual reality, smartphones, distance/virtual learning, and more. As you can see in Table 3.1, scientists study from conception, when life begins, until death, or as some have said, “From the womb to the tomb.” Consequently, throughout this chapter, we will look at each major developmental period across the lifespan. As a general framework, we will begin each developmental domain with the prenatal period (from conception to birth) or infancy (birth through 1 year), continue through childhood (birth through approximately age 12) and adolescence (age 12 through 21), and finally adulthood (age 21 through death). However, before moving on, some issues need to be briefly addressed. Specifically, we will discuss integration, standard research methods used in developmental psychology, and some of the theoretical questions that frame developmental research. Table 3.1 Periods of Development across the Lifespan Period of Development Approximate Age Range Prenatal Conception–birth Infancy Birth–1 year Toddlerhood 1–3 years Early Childhood 3–6 years Middle Childhood 6–12 years Adolescence 12–21 years Emerging Adulthood 21–25 years Early Adulthood 21–40 years Middle Adulthood 40-65 years Late Adulthood 65 years until death INTEGRATING THE BIBLE WITH DEVELOPMENTAL PSYCHOLOGY As we noted previously, developmental psychology is a very broad discipline. Although we have attempted to integrate the Bible at numerous points in this chapter, it is impossible to cover it comprehensively. What we can offer, however, are some guiding principles to help integrate the Bible as you read through this chapter or encounter the virtually limitless topics covered across developmental domains and periods in the future. You will recall from Chapter 1 that Scripture can be broken into the four separate major historical epochs of creation, fall, redemption, and restoration. The Grand Narrative of Scripture allows us to connect development with the overarching story of Scripture and gives us a simple interpretive framework for every topic presented in this chapter. Creation In the beginning, God created everything and declared it good (Genesis 1). This included the physical universe and human beings. The first man God created had a body formed from the dust of the ground, and God breathed life into him (physical and spiritual domains). Adam and Eve were created in knowledge, righteousness, and holiness after the image of God. Being made in the image of God, humans are rational (cognitive domain) and relational beings (socioemotional domain). Adam and Eve had perfect communion with God, and the universe operated as it was originally designed to function. Fall The effects of the fall were catastrophic. Things are no longer the way they should be. When sin entered our world, it brought decay and death to our bodies. Our bodies make visible the invisible reality of sin’s destructive power as we suffer from sickness, disease, pain, and death. We now witness people age and decline and babies born with chromosomal abnormalities and developmental delays; we see people suffer from addictions and mental health disorders. Under the curse of sin, the image of God in man is marred but not gone. Cognitively, we experience the noetic effects of sin, which leave our minds darkened, and futility in our thinking. Our ability to reason is clouded, so we suppress the truth, leaving us plagued with doubt and unbelief. We see good as evil and evil as good because of our moral depravity and bondage to sin. Our relational and emotional struggles reflect the socioemotional effects of sin. Scripture provides a salient example of this in the story of Cain and Abel. Within one generation of sin entering the world, we see anger lead Cain to kill his brother Abel (Genesis 4). Spiritually, we are separated from God. When sin entered the world, Adam and Eve were removed from the garden where they had previously had perfect fellowship and communion with God. Redemption Redemption is the work of Christ in restoring things to their original order and purpose. Through His death, burial, and resurrection, Jesus Christ conquered sin and death, and we can now experience redemption and reconciliation through faith in His atoning work. Although believers are released from their bondage to sin, they continue to experience the effects of sin during their lifetime and will eventually experience physical death (unless Jesus comes before we die). Until then, we can experience the redeeming work of Christ in physical, cognitive, socioemotional, and spiritual domains. As it relates to our physical bodies, Scripture tells us they were bought by Christ and become a temple of the Spirit. We can honor God with our bodies. We do that through our obedience, worship, and by presenting our bodies to God as a living sacrifice (Romans 12:1-2). Cognitively, He is transforming us by the renewing of our minds. We no longer suppress the truth but instead can offer worship to our creator. Being released from the slavery of sin, we become slaves to righteousness (Romans 6:15-23). We are able to discern God’s will and can know good from evil. Socioemotionally, we are reconciled to God through Christ and are united to other believers by the Holy Spirit and our union with Christ. Being members of Jesus’ body, we experience sweet fellowship with other believers as we worship the Lord and serve each other. We bear one another’s burdens and comfort others as we have been comforted by God. We also experience peace with God, who calls us His children and who we call Father. Restoration Although we continue to struggle with sin and all of creation suffers under sin’s curse, all creation will be restored to its original design one day. In this new heaven and new Earth, there will be no more pain, no more crying, and no more death. We will be fully conformed to the image and likeness of Christ, and just as we share in His sufferings, we will share in His Glory! As we seek to promote growth and development that leads to wholeness with Christ, let us not forget that our Lord and Savior condescended to us by becoming incarnate. In His humanity, He experienced development. He went through the fetal period, infancy, childhood, and adolescence and was an adult when He died on the cross for our sins. Although we can only speculate about His life before His ministry, Luke 2:52 gives us a small glimpse into Jesus’s development as a 12-yearold: “Jesus increased in wisdom (cognitive domain) and in stature (physical domain) and in favor with God (Spiritual domain) and man (socioemotional domain).” RESEARCH METHODS IN DEVELOPMENTAL PSYCHOLOGY Scientists can study development because people generally follow predictable patterns of growth and decline. Still, there can be variations from person to person, generation to generation, and even across cultures. Psychologists try to determine typical development during a particular period, which provides a good starting point for comparing individuals and determining whether their development is occurring along a normal continuum or if development is atypical. As discussed in Chapter 1, using the scientific method to study human behavior is complicated. Studying behavioral change across the lifespan further complicates the research, so unique methods are required. Quasi-experimental designs are commonly used to understand possible mechanisms of change at different points in one’s development. Instead of randomization, participant groups are defined by the non-manipulated subject variable of age. We will talk about the three developmental designs below. In a longitudinal design , data is collected on individuals repeatedly over time, often for many years or even decades. For example, researchers investigating the effects of aging on cognition may interview the same group of individuals yearly from 50 years old until 60 years old. Since researchers can collect data on variables in the same group of individuals as they grow older, they can draw conclusions about changes that occur in individuals as they age. This provides valuable data on regular developmental patterns. However, there are some disadvantages to using longitudinal studies. First, they can be very costly and time-consuming. It is also difficult to track and maintain participants since these studies can last for many years. In our example above, we can see how attrition could be a problem due to the participants’ age and potential health issues. Another disadvantage is the potential for practice effects . Practice effects are when repeated testing of the same variables results in a change in behavior or performance. For these reasons, most researchers use a cross-sectional design. In contrast to longitudinal designs, cross-sectional designs collect data on individuals, of different chronological ages, at the same point in time. Using the same example as above, researchers investigating the effects of aging on cognition may interview a group of 50-year-olds, a different group of 55-year-olds, and another group of 60-year-olds, at the same time. This design allows the researchers to compare different age groups in a shorter period and at a much lower cost. However, cross-sectional designs have their disadvantages as well. A disadvantage of this design is that differences between groups may be attributed to cohort effects rather than age alone. Development occurs within a historical and sociocultural context, so each generation, or birth cohort , experiences different societal, cultural, and familial influences that can confound age-related changes and differences. This makes it difficult to determine if age or birth cohort is responsible, especially in studies with significant age gaps. Finally, there are sequential designs , which are sometimes called crosssequential designs . Sequential designs have elements of both longitudinal and cross-sectional designs. Using the example above, researchers could study the effects of aging on cognition by interviewing a group of 50-year-olds, a group of 55-year-olds, and another group of 60-year-olds at the same time, then reinterview each group yearly for the next 10 years. Sequential designs have the advantage of being able to examine change in numerous age groups in a shorter period of time compared to longitudinal designs. Additionally, it allows researchers to test for cohort effects. Among the potential disadvantages are attrition and practice effects. HOW WE DEVELOP: THEORETICAL CONSIDERATIONS Several major theoretical assumptions in developmental psychology need to be considered. These assumptions are important because they help guide much of the research in the discipline and have been the center of much debate. We will briefly address the following four areas: • Nature versus Nurture • Stability versus Change • Continuity versus Stages • Passive versus Active Processes One of the oldest debates in psychology is nature versus nurture . In developmental psychology, the nature-nurture debate centers on the degree to which our genetics and other biological factors (nature ) and environmental factors or experiences (nurture ) influence development. Stability versus change concerns which traits present at birth and early childhood remain stable over time or if they change. In continuity versus stages , continuity refers to gradual, measurable changes over time, whereas stages refer to discrete changes that are categorically different. Finally, the passive versus active processes debate is concerned with the role of the individual in development. Are there external factors that determine development, or is it something innate in each child? Those who hold to passive processes of development argue that the environment and personal experiences shape development and that humans are largely passive in the process. In contrast, those who hold to active processes believe that people help shape their experiences by their active engagement in the environment and regulating their behaviors. Most of the current research reflects a move away from extreme positions on either side of these issues, and there is a growing interest in understanding how the interaction of both influence development across the lifespan. This has practical implications, and as you read through the rest of the chapter, you will want to keep these approaches in mind. To summarize, development is a lifelong process of growth and decline across multiple domains and within multiple contexts. SPEAKING WITH A DEVELOPMENTAL PSYCHOLOGIST PHYSICAL DEVELOPMENT Physical development is foundational to the other domains of development. Although many of the external changes associated with physical development are obvious, internal changes are also occurring that are not as apparent. In this section, we will look at some of the major areas of physical development, some obvious and some not so obvious, from conception until death. Physical Development in the Prenatal Period The study of human development begins at the moment of conception when life begins. The 9-month period from conception to birth is called prenatal development , and it is divided into three periods: the germinal period (conception to about two weeks), the embryonic period (2 weeks to 8 weeks), and the fetal period (8 weeks until birth). It truly is an extraordinary and unparalleled period of rapid, complex growth and development. What starts as a microscopic onecelled organism will be a fully formed baby in only nine months. Yet, each period is affected by a combination of genetic and environmental factors. In the section that follows, we will briefly look at both. The Germinal Period The first and shortest stage of prenatal development is the germinal period . It begins at conception and lasts roughly two weeks. Conception (or fertilization) occurs when a single sperm penetrates an egg allowing the sperm nucleus and the egg nucleus to fuse to create a single-celled organism called a zygote . During this fusion, 23 chromosomes from the father and 23 chromosomes from the mother combine, giving the zygote 46 chromosomes and a unique genome . This unique zygote made from a man and a woman is the literal fulfillment of two becoming one flesh (Genesis 2:24; Matthew 19:4; Ephesians 5:3) and is a new life made in the image of God. It has all the genetic information needed to become a fully formed baby. Sex is already determined as well as many other physical and psychological traits. Within 36 hours, the zygote begins to divide into more cells in a process called mitosis . The cells will divide until it becomes a mass of cells called morula on day four or five and then a blastocyst around day six or seven. At the same time, it has been migrating from the fallopian tube toward the uterus. Once the blastocyst has descended into the uterus, it will burrow into the lining of the uterine wall. During this process, called implantation , the blastocyst’s outer cells attach to the wall and begin to form the placenta, which will deliver needed oxygen and nutrients and excrete waste throughout pregnancy. The outer cells will also begin to develop the amniotic sac and umbilical cord, while the inner cells form the embryo. Not all implantations are successful, but if successful, it signifies pregnancy and initiates the embryonic stage. Figure 3.1 Human Development from Ovulation to Implantation What Does the Bible Say? What does the Bible say about prenatal development? When we look through Scripture, it is clear that prenatal development is important and that a person is important to God even before birth. Psalm 139:13-16 reads: For you formed my inward parts; you knitted me together in my mother’s womb. I praise you, for I am fearfully and wonderfully made. Wonderful are your works; my soul knows it very well. My frame was not hidden from you, when I was being made in secret, intricately woven in the depths of the earth. Your eyes saw my unformed substance; in your book were written, every one of them, the days that were formed for me, when as yet there was none of them. In the book of Jeremiah, we read that Jeremiah was called to be a prophet while still in his mother’s womb. Jeremiah 1:5 says, “Before I formed you in the womb, I knew you, and before you were born, I consecrated you; I appointed you a prophet to the nations.” Similarly, Isaiah was appointed by God while he was being formed in his mother’s womb. Isaiah 49:1 says, “Listen to me, O coastlands, and give attention, you peoples from afar. The LORD called me from the womb, from the body of my mother; he named my name.” Furthermore, Ephesians 1 tells us that God chose us in Christ before the foundations of the world, and 2 Timothy 1:9 says, “before the ages began…” Before God created space and time, He knew us and loved us in Christ Jesus. It is also worth mentioning that in the New Testament, the Greek word used for an unborn child (βρέφος/brephos) is the same word used for an infant. It seems that Scripture makes no distinction between a born or unborn child and that both are seen as God’s image bearers. Although there continues to be much debate in the world about when an individual is “human” and has rights to life, God’s Word is very clear. Within the womb, and even before conception, God has known each person, and they are His image bearers. Embryonic Period Weeks 2 through 8 are the embryonic period . It is during this time that the most rapid and critical development occurs. Cells continue to divide, differentiating into layers that will take on specialized functions. All of the major structures (i.e., heart, lungs, kidneys, eyes, limbs, genitals, etc.) and systems (i.e., central nervous, circulatory, respiratory, skeletal, etc.) begin to develop during this time. When the embryo is about 3 weeks old and only a sixth of an inch long, a heartbeat can already be detected using a transvaginal ultrasound. By week four, the brain and spinal cord begin to develop along with neurons and synapses. As the brain grows in utero, it will generate new neurons at the rate of 250,000 per minute and will reach more than 100 billion neurons by birth. By the end of this period, spontaneous movements are noted; all the basic structures for vital organs have been formed; and the embryo’s face, limbs, and digits are discernable, giving it a much more human-like appearance. During this time of rapid development, the embryo is also most vulnerable. Exposure to toxins, substances like drugs and alcohol, infectious diseases, stress, or poor nutrition can have devastating consequences on the developing embryo, and abnormalities are most likely to occur during this period. We will take a closer look at the environmental threats to development later in this chapter. Fetal Period The last and longest stage of prenatal development is the fetal period . It is marked by rapid growth and maturation. During this seven-month period, all the structures and systems that began to develop during the embryonic stage begin to function. Muscles and bones form and strengthen, reflexes appear, and the fetus becomes capable of making movements by the sixteenth week. As early as week 18, hearing starts to develop, and by week 24, the fetus may respond to its mother’s voice. Organs have formed enough that they can now survive outside the womb. During the last few months of pregnancy, brain cells multiply rapidly, and the fetus gains considerable weight and size, including a layer of fat as it prepares for birth. Figure 3.2 The Embryonic and Fetal Periods Birth Most healthy pregnancies will go full-term (38 to 42 weeks) before the onset of labor. The three-stage process of labor and delivery begins with regular contractions of the uterus, which causes the cervix to dilate (open) and efface (shorten). As contractions intensify and the baby descends toward the birth canal, most women will feel a strong desire to push. The second stage of labor occurs when the mother pushes the baby through the birth canal, and it is born. The final stage of labor is the delivery of the placenta. (See Figure 3.3.) Figure 3.3 The Stages of Childbirth At 1 and 5 minutes after birth, babies are assessed using the APGAR Scale (Bregman, 2005). This scale gives medical providers a quick and easy method to evaluate the baby to determine how well it tolerated the delivery process (1minute) and how it is acclimating to being outside the womb (5- minutes). This allows medical providers to provide the necessary support if the baby is experiencing any crises, especially around cardiac (i.e., heart) or pulmonary (i.e., breathing) issues (American College of Obstetricians and Gynecologists, 2015). The baby’s appearance (skin color), pulse (heart rate), grimace (reflexes), activity (muscle tone), and respiration (breathing) receive a score of 0, 1, or 2. Scores between 7 and 10 are considered reassuring or within the normal range. A score between 4 and 6 is moderately normal, and some medical intervention may be needed. Scores between 0 and 3 are concerning and indicate that immediate medical intervention is needed. Risks during Prenatal Development Development is guided every step of the way by the genetic information passed on from the mother and father. However, environmental factors can change the way genes are expressed. These gene-environment interactions are directly related to the nature versus nurture debate described earlier in this chapter. There are an estimated 8,000 diseases that are connected to mutations in single genes (Kaplan, 2002). Thankfully, improved prenatal care and advances in medical technology have reduced many of the risk factors associated with complications during birth and congenital abnormalities. For instance, the availability of prenatal vitamins and foods fortified with folic acid has reduced folate deficiencies in women, which can cause neural tube defects (NTDs) like anencephaly and spina bifida in their babies. Likewise, much has been learned about prenatal development in recent years because of advancements in imaging technology, especially ultrasounds. Ultrasounds allow for relatively detailed pictures and videos (sonograms) and are even capable of providing three-dimensional (3-D) and four-dimensional (4-D) imaging. This has given us the ability to see fetal development and movement as we have never seen it before, and through ultrasounds, doctors can monitor growth, identify sex, and determine abnormal development and physical defects. Blood tests can screen for chromosomal disorders such as Down syndrome (Trisomy 21), Patau syndrome (Trisomy 13), or Edwards syndrome (Trisomy 18) in the first and second trimesters. Other available screenings include amniocentesis which tests fetal cells from amniotic fluid and chorionic villus sampling which tests fetal cells from the placenta. Unfortunately, abortion rates are very high for babies diagnosed with chromosomal abnormalities in utero. Estimates suggest that 67% to 91% of babies diagnosed with chromosomal disorders are aborted (Mansfield et al., 1999; Natoli1 et al., 2012). In fact, down syndrome, which is one of the most common chromosomal disorders, has nearly been eradicated in Iceland (Quinones & Lajka, 2017). Figure 3.4 The Stages of Embryo Development Throughout the prenatal period, the baby is relatively safe in its mother’s womb. As it floats in amniotic fluid, it is protected from injuries and changes in temperature. The placenta also filters out many potentially harmful substances. However, there are many environmental factors that pose a risk to the developing fetus. A teratogen is an environmental agent that causes damage to a developing embryo or fetus. Since the baby is connected to its mother through the placenta, these agents can be anything the mother ingests, feels, or experiences. Ultimately, the impact of teratogens on prenatal development depends on the type and extent of exposure, the period of development, and genetic susceptibility. Exposure during the most critical periods of development can lead to serious and often irreparable health problems, congenital defects, and/or deficits in adaptive functioning. Teratogenic agents can include infectious agents and diseases (e.g., measles, rubella, chickenpox, herpes simplex, toxoplasma, syphilis, etc.); maternal factors (e.g., genetics, health, stress, aging, and malnutrition); environmental agents (e.g., mercury, radiation, lead, herbicides, industrial solvents, etc.), metabolic conditions (e.g., diabetes, maternal phenylketonuria); and drugs (e.g., over-thecounter, prescription, recreational, alcohol, tobacco/nicotine) (Genetic Alliance, 2017). Some of the leading preventable causes of birth defects and developmental disabilities are a result of drug exposure. Mothers who consume substances, like alcohol, during sensitive periods put their unborn children at risk for brain damage and other impairment. Facial abnormalities, for example, are most likely to arise from mothers’ drinking in the first 2 months of pregnancy. Pregnant women also put their children at risk by smoking or vaping, particularly in the second half of pregnancy. Smoking and recreational drug use during pregnancy increase the risk of miscarriage, premature births, low birth weight, and sudden infant death syndrome (SIDS). Perinatal (the period of weeks directly before and after birth) drug exposure symptoms include the following (Jansson et al., 2009; Minnes et al., 2011): Pregnancy complications Prematurity Decreased weight and length Decreased head circumference Small gestation age Intraventricular hemorrhage (i.e., bleeding in the brain) Fetal abstinence syndrome Stillbirth Sudden infant death syndrome (SIDS) Increased infant mortality (i.e., death) Of all the substances abused during pregnancy, alcohol produces some of the worst outcomes and has been estimated to affect 630,000 babies born across the globe annually (Lange et al., 2017). Although there is evidence to suggest that the relationship between alcohol and adverse birth outcomes was known prior to the 20th century (see Judges 13:7), it was not until about 1973 that fetal alcohol syndrome (FAS) became a formal postnatal diagnosis. Today, fetal alcohol spectrum disorder (FASD) describes the variety of physical and mental health conditions caused by prenatal exposure to alcohol (see Figure 3.5). Included under the umbrella of FASD is partial fetal alcohol syndrome (pFAS), alcohol-related neurodevelopmental disorder (ARND), alcohol-related birth defects (ARBD), and neurobehavioral disorder associated with prenatal alcohol exposure (ND-PAE) (Lange et al., 2017; Popova et al., 2017). Over 400 comorbid medical and psychological conditions have been identified that co-occur with FASD (Popova et al., 2016). Figure 3.5 Fetal Alcohol Syndrome Prenatal exposure to alcohol can lead to congenital defects, chromosomal anomalies, and deficits in cognitive, behavioral, emotional, and adaptive functioning (Lange et al., 2017; Popova et al., 2017). It is well established that it can cause significant damage to the brain and the rest of the central nervous system (CNS) and can lead to low birth weight, microcephaly (small head), abnormal facial features, vision problems, hearing problems, and heart defects. In addition to the host of potential physical problems, there are many mental and behavioral disorders associated with FASD. The prevalence of disorders like attention-deficit/hyperactivity disorder (ADHD), anxiety disorder, bipolar disorder, depression, oppositional defiant disorder, posttraumatic stress disorder, reactive attachment disorder, psychotic disorders, learning disabilities, and intellectual disability significantly increase in prevalence for children diagnosed with FASD. In fact, FASD is the number one cause of intellectual disability in the United States, and there are many behavioral and psychological symptoms that are associated with prenatal alcohol which are listed below (Burger et al., 2011; Foltran et al., 2011; Larkby & Day, 1997; Paintner et al., 2012; Popova et al., 2011; Sood et al., 2001). Attention deficits Hyperactivity Poor impulse control and judgment Poor coordination and motor skills Learning disabilities Speech delays Intellectual disabilities Memory deficits Difficulty with abstract thinking Poor problem-solving skills Inability to learn from consequences Poor social skills Poor emotional regulation Recreational drug use (e.g., cocaine, marijuana, methamphetamines, opioids, etc.) during pregnancy continues to be a major problem. Recently, the opioid crisis has created a tremendous problem for babies born dependent upon opioids. The term for this phenomenon is neonatal abstinence syndrome (see Table 3.2). Babies born exposed to such drugs have many issues, including withdrawal symptoms. These symptoms often occur between the first 2 to 7 days after birth. Peak symptoms manifest themselves around days 10 through 21 but may last up to 6 months. Sadly, these at-risk, high-need babies often go home to an environment that increases risk due to poor maternal/paternal support. These babies are harder to take care of because of their continued substance exposure symptoms, and their parents are often still dealing with substance use problems. Combining biological risks with an often chaotic and dysfunctional environment makes healthy early growth and maturation nearly impossible. This is effectively the nature versus -nurture problem. Table 3.2 Neonatal Abstinence Syndrome Symptoms Central Nervous System Gastrointestinal System Metabolic, Vasomotor, and Respiratory Unusual irritability, fussiness High-pitched crying Hypersensitivity to stimuli Tremors Seizures Skin irritation on knees, elbows, and face from hyperactivity/squirming Changes in muscle tone Sleep disturbances Dehydration Poor feeding Regurgitation/throwing up Diarrhea Skin irritation on buttocks Excessive sucking activity Nasal stuffiness, sneezing Frequent yawning Fever Sweating Tachypnea/rapid breathing Apnea/suspension of breathing Note. (Jansson et al., 2009; Minnes et al., 2011; Pediatrics, 1998) Of course, assigning a poor birth or developmental outcome to prenatal drug exposure is very hard, as many variables can impact early development. The most significant problems are the co-occurrence of risk factors such as the following non-exhaustive list: More than one drug used/abused during pregnancy (polysubstance use) Poor maternal health Lack of prenatal care Poor nutrition High levels of stress Preexisting health or behavioral problems Genetic predisposition to particular issues or diseases Low educational attainment Low socioeconomic status Lack of social support Birth problems Poor neonatal environment Inadequate child-rearing environment Observational bias Inaccuracy of diagnostic tests Lack of long-term follow-up Child abuse and neglect It can be challenging to distinguish prenatal drug exposure from a poor childrearing environment, and frequently the two problems co-occur. Although substance use often decreases during pregnancy, the postpartum relapse rate is alarmingly high (80%) (Forray et al., 2015). Even if a mother abstains from drug use during her pregnancy, the overwhelming likelihood is that she will continue to use drugs across much of her newborn’s and infant’s formative years. Unfortunately, this results in a cascade of developmental issues that set the child up for similar patterns of maladaptive behavior. When examining the relationship between substance abuse and child maltreatment, there is a strong association between parental substance abuse and gross neglect, physical maltreatment, and sexual maltreatment (Famularo et al., 1992). Despite the many risks to prenatal development, we were created by God to be resilient. Yet, we are called to be wise stewards of our children, and that stewardship starts during pregnancy and will continue throughout their lives. PHYSICAL DEVELOPMENT IN INFANCY AND CHILDHOOD Reflexes God designed newborns (also known as neonates ) to come prewired with a variety of reflexes that help them survive and thrive in their new worlds. These reflexes are involuntary and unlearned motor responses to sensory stimuli. They help newborns adapt to and engage with the world around them until they can learn to control their movements voluntarily. Reflexive behaviors like breathing, blinking, coughing, and gagging will stay with us throughout our life. However, several motor reflexes present during infancy will disappear (integrate) as perceptual awareness and motor skills improve (see Table 3.3). If babies retain these reflexes past the normal period, it could be a sign of problems with the central nervous system. Table 3.3 Summary of Infant Reflexes Reflex Stimulus and Response When Reflex Disappears Sucking Reflex Infants will close their lips and suck on anything placed in their mouth. About 2 Months Moro Reflex The baby will arch their back and extends their arms and legs when startled by a loud noise or sudden movements. It is often called a startle reflex. About 2 Months Crawling Reflex When placed on their stomachs, infants will make crawling motions. About 2 Months Stepping Reflex When held upright with feet touching a hard surface, infants will make a walking or dancing motion. It is often called the walking or dancing reflex. About 3 Months Rooting Reflex When the baby’s cheek or the corner of their mouth is stroked, infants will turn their head toward the touch and open its mouth. About 4 Months Grasp Reflex Touching the baby’s palm causes their fingers to grasp. About 6 Months Tonic Neck Reflex Also called the fencing reflex, it is when rotating the head to one side causes the arm and leg to straighten in the same direction while the opposite arm and leg bend. About 6 Months Galant Reflex While face down, if the baby’s lower back next to the spine is stroked their hip will move to the side that is stroked. 6 to 9 Months Babinski Reflex When the inner sole of the foot is stroked, the toes will curl. When the outer sole is stroked, the big toe will point upward and the other toes will fan out. 6 to 24 Months Sensation and Perception Newborns can respond to stimuli because they have functioning sight, hearing, smell, taste, and touch. In fact, hearing, smell, taste, and touch are particularly welldeveloped by birth. Touch is the first of the senses to develop during the prenatal period and is probably the most dominant of their senses throughout gestation and infancy (Addabbo et al., 2015). After birth, babies can distinguish between self-touch and external touch. For instance, babies will not respond with a rooting reflex if their own finger strokes their cheek. Physical touch has also been shown to calm stress responses and comfort babies that are in pain. Likewise, the taste and smell of a mother’s breastmilk reduce stress and pain responses. Babies can identify their mother by smell and prefer the taste of their breast milk over formula (Lin et al., 2022). They also prefer sweet flavors over bitter or sour ones. Hearing also appears early in the prenatal period and is quite developed by birth. Studies have shown that newborn babies prefer the voice of their mothers over others and their mother’s native language over foreign tongues (DeCasper & Fifer, 1980; Kisilevski, et al., 2008; Lin et al., 2022; Todd et al., 2022). Between 4 and 6 months, babies will recognize and try to repeat sounds; by 12 months, they should be able to recognize and follow sounds that come from behind or from the side. Sight is the least developed of all the senses at birth, with newborns only being able to focus on objects within 8 to 10 inches, which happens to be about the distance of a mother’s face when a baby is breastfeeding. They cannot distinguish between similar color tones very well, so they prefer high contrast like black and white. They can make out shapes and will gaze longer at images that resemble faces. It does not take long before they can recognize their mother’s face. At about 3 months, babies will be able to follow moving objects with their eyes. By about 6 months, they will be able to reach out and grab objects and will have full color vision. Visual acuity continues to improve, reaching 20/20 as early as three years old. Likewise, depth perception will be fully developed between 4 and 6 years old. Motor Skills Sensation and perception are inextricably linked to motor development because they provide fundamental information about our environments and allow us to receive continuous feedback about our own actions. This is essential for the transition from reflexes to voluntary movements because experimenting with movements helps us learn motor skills. However, motor skills , which refer to the ability to control and coordinate bodily movements, involve the central nervous system and the musculoskeletal system. This means that motor skills are not only dependent on the brain’s ability to interpret sensory stimuli but also on physical maturation. In this context, maturation refers to the biological growth and development that occurs because of the typical aging process (nature) rather than the influences of the environment or learning (nurture). As the baby grows physically, motor skills also develop in an orderly sequence, following what is known as cephalocaudal and proximal-distal principles. The Cephalocaudal (head to tail) principle asserts that development follows a headto-toe pattern. This principle is best illustrated by an infant’s disproportionally large head and relatively small arms and legs. Since their heads are so large, it will take about 2 months before they can raise their heads. Within 6 months, they will gain enough control of their arms to hold a bottle with two hands, and at approximately 12 months, they begin to walk. Similarly, proximal-distal (near to far) development starts at the center of the body and moves outward. We can see this principle at work in the way the head and torso develop before the arms and legs. Likewise, infants will then gain control of their hands and feet before their fingers and toes. Motor development also follows the principle of simple to complex, or general to specific. This is why humans typically crawl before they walk and walk before they run. We also see this in the way that gross motor skills are achieved before fine motor skills. Gross motor skills are larger movements that involve the coordination of large muscles of the body. In contrast, fine motor skills are the smaller movements that involve the coordination of the smaller muscles in your body. Gross motor skills primarily rely on strength, coordination, and balance, using the legs, arms, and core. Fine motor skills require much more precision and control and usually involve the hands and fingers. Gross and fine motor skills build upon each other, and tremendous improvements in both will be made throughout infancy and childhood. Typically, babies begin rolling over at around 3 months, sitting up at 5 months, and crawling somewhere between 7 and 10 months. By 12 months, infants are often capable of standing and walking, grabbing items with their index finger and thumb, and feeding themselves finger foods. By age 2, they can already kick and throw a ball, take their clothes off, and turn a doorknob. During the preschool years (3 through 5), most children will be able to run, jump, climb, kick, throw a ball, and maybe even ride a bike (most likely with training wheels). As they move into middle childhood, they will continue to master gross motor skills such as riding a bike or throwing and catching a ball and will continue to hone fine motor skills like drawing, handwriting, or tying shoes. Although there is variation in the ages that these skills emerge, significant delays in motor skills may be a sign of developmental delays or neurological disorders. Doctors use developmental milestones or what are often called developmental norms to help determine if there may be a problem. Developmental norms refer to developmental characteristics that occur within a normal distribution , or a bell curve (see Figure 3.6). The bell curve is a probability distribution with the majority of data points being represented toward the middle or mean. Doctors and psychologists can use this information to predict typical growth patterns and the ages when skills and behaviors usually develop. When children fall too far outside the normal distribution, they may have a delay or more serious condition. Developmental norms are considered across various developmental domains, so they are not limited to motor skills alone. Developmental milestones like language, social skills, and adaptive skills are just a few monitored areas. Developmental delays across numerous domains may indicate a need for early intervention or special education, but contextual and cultural factors should be considered during assessment. However, motor skills would not be possible without the continued maturation of the musculoskeletal system and the central nervous system. Figure 3.6 Bell Curve of Developmental Characteristics Musculoskeletal Growth Both gross and fine motor skills require increased strength and coordination as they develop. The musculoskeletal growth experienced in the early years is needed particularly for gross motor skills, whereas fine motor skills are developed more in middle childhood. In the first year, babies grow about 10 inches and triple their birth weight. In the second year, they can grow another five inches and gain another five pounds. Throughout early childhood, children will gain about four or five pounds and two to three inches a year. In middle childhood, height increases by about 2.5 inches a year while weight increases by about four to seven pounds per year. Just like motor skills, musculoskeletal growth during these early years is compared to developmental norms. Extremes on either side of the growth bell curve can indicate some abnormality or delay and must be monitored. Brain Development As we mentioned earlier, babies have very large heads in proportion to their bodies, and that is because they have big brains. At birth, a newborn’s brain is about one-fourth the size of an average adult’s brain. Within one year, it will double in size; by 5 years, a child’s brain will be about 90% of an adult-sized brain. The proportionally large heads and significant increases in size during infancy and early childhood are also reflective of other structural and functional changes that occur within the brain. The development of sensory perception and motor skills is not possible without the continued maturation of the brain. However, brain development during these early years is experience-dependent (Guyer et al., 2018). This means that every activity and sensory stimulus a baby or child experiences fosters brain development. Therefore moving, exploring, and interacting with people is so important during this time. Changes to the brain’s size, structure, and functionality -during these early years are fundamental to functions like perception, gross and fine motor skills, memory, language, attention, and self-regulation (Guyer et al., 2018). Conditions during these early years are optimal for brain development, and this time is also considered a critical period. A critical period is when the successful acquisition of specific functioning is limited to a specific period. For instance, sensory deprivation during these critical early years has been shown to result in lifelong perceptual and processing deficiencies. The early years are such a critical period for brain development because neural connections will be rapidly established during the first two to three years of life. Although infants have about 100 billion neurons at birth, neural connections are very limited and immature. However, as infants and children encounter new sensory stimuli and physically engage with their environments and with people, their brains add neural connections called synapses. You will recall from Chapter 2 that a synapse is a gap between the end of an axon and a dendrite through which neural impulses (neurotransmitters) travel. Although these connections are relatively simple, they are foundational to learning and for more complex and specialized connections later in life. It is now believed that during the first three years of life, the brain creates 1 million neural connections per second (Harvard, n.d.). At this point in life, the brain will have more neural connections than at any other point. In middle childhood and adolescence, the brain will eliminate the overabundance of neural connections accumulated during this time. In the adolescent brain development section, we will discuss this process in more detail. PHYSICAL DEVELOPMENT IN ADOLESCENCE Adolescence is the developmental period that begins with the onset of puberty and marks the transition from childhood to adulthood. Generally, adolescence is subdivided into early adolescence (ages 12–14), middle adolescence (ages 14–18), and late adolescence (ages 18–21 and older) and is characterized by the following: Rapid physical growth Changes in sleep patterns Change in appetite Changes in hormones Sexual maturation Secondary sexual characteristics Changes in body shape Increases in strength and endurance Menstruation in females Changes in vocal sound Puberty Puberty can be defined as the period of rapid physical growth that leads to sexual maturation and the ability to reproduce. Although there is a predictable sequence to the changes experienced during puberty, the age of onset and duration can vary considerably. Puberty can last 2-5 years, with onset for females ranging between ages 8 and 13 and between ages 9 and 14 for males (Breehl & Caban, 2022). Onset is largely dependent on changes in the brain and hormone levels. Puberty is initiated in the brain when gonadotropin-releasing hormone (GnRH) from the hypothalamus signals the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH then stimulate the release of estradiol and testosterone from the gonads (i.e., ovaries in females and testes in males) (NICHD, 2021). It is the increase in these sex hormones that is responsible for the development of the primary and secondary sex characteristics. Primary sex characteristics are bodily structures present from birth that are directly involved in reproduction. They include both internal and external genitalia, such as the penis, testes, and seminal vesicles in males and the vagina, ovaries, and uterus in females. Boys may experience their first ejaculation, called spermarche or semenarche , and girls will have their first menstrual cycle, called menarche . Most girls may start their period around age 12, which is 2–3 years after breast budding. Secondary sex characteristics refer to bodily structures that do not emerge until puberty and are not directly involved in reproduction. These include pubic hair and underarm hair in both sexes. Other characteristics differentiate males and females. Males grow chest and facial hair, their voice deepens, they develop Adam’s apple, and their shoulders broaden. Females’ breasts grow, their pelvic bones widen, and more fat accumulates about the hips making them fuller and wider. These differences in primary and secondary sex characteristics, along with the brain, hormones, and anatomy, distinguish females from males and are called sex differences . They are genetically determined, universal, and unchanging. In contrast, gender differences are learned sexual attitudes and behaviors that are socially and culturally influenced. Gender roles are the typical patterns of behaviors that are considered culturally and socially appropriate and provide the parameters for femininity and masculinity. This is directly related to gender identity , which is typically used to describe one’s personal sense of femininity and masculinity. Probably the most outwardly obvious sign of puberty is the adolescent growth spurt. A growth spurt is a period of significant increases in height and weight in a relatively short period of time. Typically, the pubertal growth spurt begins between ages 9 and 10 for girls and ages 11 and 12 for boys, with peak growth starting at ages 11.5 and 13.5, respectively (Solliman et al., 2014; Tanner & Davies, 1985). Although boys are usually larger than girls throughout infancy and childhood, there is a brief period during adolescence when girls are often taller than boys. This occurs because females usually begin their pubertal growth spurt a year or two earlier than males. Boys tend to catch up, growing up to 4 inches a year, while girls will grow up to 3.5 inches a year. (Again, it is important to remember normal distributions/bell curve.) Figure 3.7 Milestones in Sexual Development By middle adolescence, growth spurts end, and sexual maturity is achieved. Physical changes in females may have already reached completion, while males may continue to experience increases in musculoskeletal growth during this time. In late adolescence, physical development is typically completed, with both sexes having reached their full adult height. The Adolescent Brain During adolescence, changes in the brain are just as rapid and dramatic as the more obvious external changes associated with puberty, and a few important concepts are helpful to discuss here. Whereas childhood brain development is primarily a time of formation and growth of new neural synapses (see Chapter 2), adolescent brain development is a time of major restructuring and reorganization. As a child reaches puberty, the brain begins to prune many of the neural synapses that it accumulated throughout childhood. Synaptic pruning is the process by which neural synapses that are not needed are eliminated. By the end of adolescence, about half of the synaptic connection will have been pruned. Although this may seem counterproductive, by removing these unused connections, more efficient and specialized networks can be established. Increased myelination is also occurring during this time. Myelination is simply the process by which myelin sheaths are wrapped around neuronal axons. You will recall from Chapter 2 that the myelin sheath insulates and protects the neurons (nerve cells). It also facilitates more efficient neural transmission. Myelination makes it more efficient because it increases the action potential (speed of neural transmissions) and reduces the refractory period (rest) needed between transmissions. This increase in pruning and myelination is vitally important to development because it ultimately results in a more integrated and higherfunctioning brain. Another related concept that is important to revisit when discussing adolescent brain development is neuroplasticity. Recall from Chapter 2, that neuroplasticity is the brain’s ability to adapt and change, both in its activity and structure, in response to learning, experiences, stress, or damage. The human brain has this ability throughout the lifespan, but it is especially important during the adolescent period as it can have long-lasting effects on cognitive and behavioral development. This is particularly noteworthy during adolescence since there tends to be an increase in risk-taking, impulsive, and sensation/novelty-seeking behaviors. (This is associated with the rapid development of certain areas of the brain and the lack of maturity in other parts of the brain, which is discussed in Chapter 2). Additionally, it can also be a time of great psychosocial stress. The good news is that these behaviors and even the increased stressors can serve to prepare adolescents for adulthood. As they become increasingly independent, seek out novel experiences, and deal with psychosocial stress, they can improve cognitive, motor, and social functioning. Positive outcomes are much more likely given a good environment with numerous protective factors in place. Although the effects of plasticity can be adaptive, they can also be maladaptive (Dennis et al., 2013; Kolb & Gibb, 2011; Kolb et al., 2017). During adolescence, the brain goes through important changes that support judgment, reward pathways, emotion arousal and regulation, and understanding of complex social experiences (Guyer et al., 2018). Any number of negative behaviors or experiences during adolescence can result in changes to neurotransmitters and brain structures, which can have lasting consequences for the brain. A good example of this is substance-induced changes. Drugs directly impact those brain centers and can result in the development of long-term emotional and behavioral problems. Drug exposure also permanently alters reward systems, which increases the likelihood of substance abuse problems throughout life (Kelley & Middaugh, 1999; Kelley & Rowan, 2004; Nolley & Kelley, 2007). These risks are not limited to drug exposure. Research suggests that technology can have similar negative consequences on brain development. Specifically, reward and attention systems in the brain can be altered. Untreated mental disorders during adolescence can also have maladaptive plastic effects (Guyer et al., 2018). We will talk more about substance abuse and mental health during adolescence later in this chapter. PHYSICAL DEVELOPMENT IN ADULTHOOD Adulthood is the longest developmental period, spanning from the end of adolescence until death. Physically, adulthood is marked by both growth and decline. Whereas physical growth in adolescence was rapid and dramatic, changes in adulthood are much more gradual and subtle. Throughout adulthood, our bodies continue to change in response to both genetic and environmental factors. In this section, we will explore the physical changes that occur during aging and will briefly discuss how adults can protect their health as they get older. Early Adulthood Early adulthood, also called young adulthood, takes place between the ages of 20 and 40. In terms of change, early adulthood is the least dramatic, with physical development peaking during this time. Individuals may experience some modest increases in height and muscular development during their early twenties. Physical abilities like reaction time, strength, coordination, agility, and stamina typically peak in the twenties, and senses are at their sharpest. Typically, bodily systems, such as the nervous, cardiovascular, respiratory, digestive, reproductive, etc., are functioning optimally during this time. In fact, women are at their most fertile and are most likely to have healthy full-term pregnancies during this period as well. However, by the thirties, there may already be a noticeable decline in physical abilities. Health issues are usually a result of risk-taking behaviors such as alcohol, drug abuse, unprotected sex, or injuries from accidents. Unfortunately, sexually transmitted diseases (STDs) continue to rise in emerging adults and adolescents, with 15 to 24 years old making up about half of the new infections in the United States (CDC, 2021). Although, it is rare for young adults to have life-threatening sicknesses, unhealthy behaviors in young adulthood can have long-term health consequences, often presenting in middle adulthood. Exercise, healthy eating, good sleeping habits, and the avoidance of smoking, drinking, and drug use can lower the chances of disease and overall decline resulting from aging. Middle Adulthood Middle adulthood begins at age 40 and continues until 65. It is during middle adulthood that more noticeable declines related to aging and appearance occur. Most will notice outward changes such as the loss of skin elasticity, graying and/or thinning of the hair, and perhaps weight gain. They may also begin to experience declines in strength, agility, and stamina. There are also declines in sensory system function, with sight and hearing being the most notable as glasses and hearing aids become more common. Changes in the reproductive system occur during middle adulthood as well. Women over 40 are less likely to get pregnant, and chances of conceiving go down each year, with natural pregnancies being considered rare by the age of 45. For those that do get pregnant, the chance of miscarriages and stillbirths goes up. Additionally, complications during pregnancy and/or delivery and chromosomal abnormalities or birth defects are more likely. Middle adulthood is also the time when women will begin to experience changes in menstrual cycles and hormone levels. Leading up to menopause , when women stop menstruating permanently, estrogen levels decrease, causing menopausal symptoms such as hot flashes, fatigue, sleep problems, irregular periods, and loss of bone density. Men typically experience a drop in testosterone, but since it is over a much longer period of time, the associated changes are not as dramatic. Middle adulthood is also the period when people start to experience more inward physical decline and health-related issues. Internally, there are gradual changes in organ systems with a general decrease in functioning. The body does not recuperate or heal as rapidly as it did when younger. Age-related illnesses like hypertension, arthritis, and osteoporosis become more common. Chronic diseases become more prevalent and may lead to death. The top causes of death for individuals in middle adulthood include the following (CDC, 2019; CDC, 2022): Accidents Cancer Heart disease Suicide Homicide Chronic liver disease and cirrhosis Diabetes mellitus Cerebrovascular disease (stroke) Nephritis, nephrotic syndrome and nephrosis (kidney disease) Septicemia (infection of the blood) COVID and/or pneumonia Chronic obstructive pulmonary disease (COPD) However, it should be noted that a combination of biological, social, and psychological factors help determine the extent of health declines in middle adulthood, so there can be quite a bit of variability (again, following a normal distribution/bell curve). For example, a healthy 50-year-old could be enjoying all of the benefits of their many years of hard work (e.g., consider Jenifer Aniston, or Paul Rudd, both in their fifties); however, around the same age, someone could begin to experience significant declines in health, which would have cascading impacts on career, relationships, and hobbies/interests (e.g., Michael J. Fox, also in his fifties, who has suffered from Parkinson’s disease for many years). Late Adulthood Late adulthood , which is the period from 65 until death, is a relatively new area of study in developmental psychology literature. Until the 20th century, most people died before age 65, but due to improved healthcare, adults are living longer than previous generations. In fact, late adulthood is the fastest-growing segment of the population. The U.S. Census Bureau projects that by 2030 older adults will be the largest age group at 21% (see Figure 3.8). Named the “Graying of America,” this aging of the Baby Boomer cohort (individuals born after WWII between 1946 and 1964) will mean that older adults will soon outnumber children for the first time in our country’s history (see Figure 3.9), and with it will come important developmental considerations that will require research, resources, and attention. Figure 3.8 The Projected Number of Children and Older Adults in the U.S. Figure 3.9 The Population Aged 65 and Over from 1900 to 2050 In addition to healthcare and economic resources that will be required to care for an aging population, there are several psychological and social implications of aging for developmental psychologists to consider. Among these areas of research and concern are coping with chronic illnesses, decreased physical functioning, cognitive decline, and quality of life. Declines in Physical Functioning and Chronic Illness The physical declines related to aging that began in middle adulthood will continue in late adulthood and may even accelerate. Outwardly, the skin will get thinner and more wrinkled, and hair may become grayer and sparser. Older adults continue to lose muscle mass and strength, and reaction time becomes much slower. For some, just getting around becomes a significant problem with 19% of adults over 65 reporting having a disability and 40% having difficulty with mobility. Sensory functioning continues to fade as well, particularly sight and hearing, with 22% of older adults having trouble seeing and 31% with hearing (Administration on Aging, 2021). Adding to the challenges of late adulthood, approximately 80% have at least one chronic illness, and 68% have at least two. The most common chronic illnesses are hypertension, high cholesterol, arthritis, heart disease, and diabetes (see Figure 3.10). Also notable are depression and dementia, which are seen in 14% and 11% of the older adult population (Healthy Aging Team, 2017). Figure 3.10 The 10 Common Chronic Conditions for Adults over 65 Years of Age Managing chronic illness and physical decline is an important part of late adulthood and will often require dietary changes, prescription medications, and help from others. Understandably, mental health and overall quality of life can become significant issues for older adults. In fact, patients with chronic illnesses are shown to have a high prevalence of comorbid depression (Katon, 2003). Furthermore, individuals with chronic illnesses report lower quality of life overall than those without chronic illnesses. The chronic illnesses that are most associated with decreased quality of life are cancer, hypertension, osteoporosis, and diabetes (Fortin et al., 2006; Li et al., 2009). We will discuss quality of life more later in this chapter. Physiological Theories of Aging and Death So why do our bodies deteriorate and eventually die? The Bible tells us that when sin entered the world, it brought sickness and death (Genesis 3). Of course, developmental psychology is interested in the physical mechanisms of aging . When they speak of it in this context, they are talking about the progressive physical declines that result in decreased functioning and increased vulnerability to sickness, disease, and injury (Lipsky & King, 2015). Numerous theories have been proposed, with most falling into stochastic theories (also known as damage or error theories) or non-stochastic theories (also known as programmed theories) (Jin, 2010; Maynard et al., 2015). Stochastic theories assert that aging is a result of external influences in the environment, while non-stochastic theories contend that aging is biologically determined. Each sees aging, and ultimately death, as starting at the molecular or cellular level. One of the earliest stochastic theories is the wear and tear theory. In wear and tear theory, aging is a result of cells and tissues wearing out with repeated use over time. Cross-linking theory suggests an accumulation of cross-linked protein is what damages cells and tissues. Aging occurs because metabolic processes are slowed due to the damage incurred. The free radical theory posits that over time cellular structures accrue damage from free radicals, eventually leading to loss of function and failure in cells and organs. Finally, according to somatic DNA damage theory, aging occurs when DNA cannot be replicated or repaired as fast as damage and defects are produced, causing cell deterioration and malfunctions (Jin, 2010; Maynard et al., 2015). There are three subcategories of non-stochastic or programmed theories. In programmed longevity theory, cells are genetically programmed for stability and instability, with aging occurring due to gene instability. One theory that falls under this subcategory is the telomere theory. Each time a cell divides, the protective ends of a chromosome, called telomeres, shorten. Eventually, they become too short to reproduce, leading to cell death. In endocrine theory, programming works through hormones which are the key regulators of aging. Finally, in immunological theory, immunological functioning decreases over time, resulting in increased vulnerability to sickness and disease. Although there are many theories of aging, no single theory has been shown to fully account for the declines we experience with age. Scientists continue to study, hoping to find ways to slow down the aging process and improve quality of life. However, aging and death are inevitable because we live in a fallen world. Yet, good stewardship of our bodies, minds, and souls can improve quality of life. COGNITIVE DEVELOPMENT Cognitive development is similar to physical development in that we typically experience rapid growth in the earlier stages of life and then decline in the later stages. This reflects the foundational nature of our physical development, particularly the brain, on cognitive abilities. In this section, we will look at some important features of cognitive development, such as perception, attention, memory, and intelligence, that occur from infancy through late adulthood. Cognitive Development from Infancy through Adolescence Cognitive abilities improve significantly throughout childhood, especially in the areas of language acquisition, memory, and reasoning. In this section, we will look at Jean Piaget’s (1896–1980) theory of cognitive development which has been very influential in the field of developmental psychology. In it, we will look at the developmental tasks associated with cognition in infancy, childhood, and adolescence. Piaget’s Theory of Cognitive Development One of the most influential figures in developmental psychology was Jean Piaget. Jean Piaget lived during the 20th century and pioneered the study of cognitive development. He studied children from infancy through adolescence (including his own three children) using naturalistic observations, controlled observations, and clinical interviews. Before Piaget, children were thought of as miniature adults with the same cognitive abilities but with less acquired knowledge. However, it was evident to Piaget that children thought and reasoned differently than adults and that cognitive ability changed with maturation and experience. Fundamental to Piaget’s theory is that children make sense of the world through experiences. He viewed children as “little scientists” who actively engaged with their environments through experimentation. As children test their ideas, they gain valuable information, recognize patterns, and draw conclusions, which can then be organized categorically into cognitive schemas. It assumes that knowledge is stored categorically for easier recall and association for future experiences. Therefore, schemas are the mental frameworks that help us to organize and interpret our experiences. They can be objects, events, actions, or abstractions, allowing us to engage in physical and conceptual operations. Piaget conceived of operations as more complex mental actions using a multitude of schemas and logical rules which could be reversed. Piaget believed schemas to be the building blocks of cognition and contended that cognitive development is driven by adaptation and equilibration. For Piaget, adaption is the innate tendency to adjust our schemata to the environment or situational needs, whereas equilibration is the process of eliminating conflicts between our schemas and the environment. Children in a state of disequilibrium must resolve cognitive conflicts to reestablish equilibrium. Both adaption and equilibrium are accomplished by what Piaget called assimilation and accommodation. Assimilation is the process of integrating new information into existing schemas. As with any new experience, we gain information that is interpreted using existing cognitive schemas, then store it in existing mental structures. Sometimes assimilation does not work because of discrepant information which requires accommodation. Accommodation is the process of altering existing schemas to integrate discrepant information. Cognitive development requires constant assimilation and accommodation of new experiences, and this will go on throughout the lifespan, becoming increasingly complex into adulthood. Piaget’s Stages of Cognitive Development Piaget is best known for his stage theory model of cognitive development. Piaget conceived cognitive development as occurring in four discrete stages, each of which is qualitatively different from the others (Piaget, 1954, 1969, 1973). According to Piaget, these stages are universal; they progress in a fixed sequence, and each stage lays the foundation for the next. Below we will take a closer look at each of the following stages: (1) the sensorimotor stage (from birth to almost 2 years), (2) the preoperational stage (from 2 to 7 years), (3) the concrete operations stage (from 7 to 11 years), and (4) the formal operations stage (from 11 years onward). The sensorimotor stage begins at birth and lasts until age two. In this stage, babies interact with their environments through their senses and motor abilities. You will recall from earlier in the chapter that newborns have functioning senses that allow them to perceive stimuli. Additionally, they are born with an array of involuntary motor reflexes that help them adapt and respond to the world around them until they can learn voluntary motor skills. According to Piaget, infants are forming schemas every time they stare at their mother, listen to her voice, drink her milk, or hold her finger. Of course, this is not just limited to interaction with their mothers. Despite what appears to be very simplistic behaviors, infants are expanding and altering their cognitive schemas. Every experience they have provides feedback that ultimately contributes to their development, and they will make leaps and bounds cognitively within two short years. As babies mature physically and motor skills improve, they are better able to coordinate sensorimotor skills to explore and interact with objects in their environment. This allows them to discover personal preferences and learn to repeat enjoyable behaviors. As they repeat behaviors, they come to a rudimentary understanding of cause and effect. With each little experiment, infants begin to make connections that help them understand the consequences of their behaviors. They also begin to imitate the behaviors of others, including sounds and words. According to Piaget, the major developmental achievement during the sensorimotor stage is object permanence. Object permanence is when we understand that objects continue to exist when not visible. Piaget believed infants did not have this ability early on, so “out of sight” is truly “out of mind.” However, by 8 months old (and some believe even sooner), babies start to demonstrate object permeance by searching for objects that are hidden from view. As object permeance continues to develop, early symbolic representations emerge in children’s play and in their use of words to represent objects (Orr & Giva, 2015), and by 18 to 24 months they are ready to move on to the next stage. The preoperational stage of cognitive development lasts from about age 2 to 7 and builds off the cognitive structures developed in the sensorimotor period. At this stage, children’s motor skills have allowed them to become more mobile, expanding their environment so that they are continually exploring and encountering new things and experiences. Symbolic thought —the ability to use mental representations for objects—is probably the greatest achievement of the preoperational stage. Children’s capacity for symbolic thinking grows, and they become more adept at using words, numbers, and images. Symbolic play also evolves. For example, we see children use sticks as swords and playground structures become forts and castles. Although their capacity to use language and symbols is a major accomplishment, there are numerous limitations that are noteworthy. As the name of this stage implies, children are not able to think operationally at this point. Thinking is more intuitive than logical and lacks the ability to reverse actions mentally, or what Piaget called reversibility . This ability is generally not seen before the age of six. Additionally, children tend to focus on the most salient aspect of a thing, to the neglect of other things. This is termed centration . Both cognitive limitations are illustrated in Piaget’s classic conservation task (Piaget, 1954). Conservation is the ability to recognize that quantities and properties remain the same even if the form is altered. To test his theory, Piaget presented children with two identical glasses filled with the same amount of water (see Figure 3.11). Children in this stage are easily able to recognize that the volume of water is the same in each glass. However, when water from one of those glasses was poured into a taller and narrower glass, preoperational children would identify the taller glass as having more water. In the case of the taller beaker, they were fixated on the height of the water (centration), and although they just watched one glass of water be poured into the other, they were not able to mentally revert the process (reversibility). Figure 3.11 Piaget’s Classic Conservation Task for Testing Conservation in Children Another key characteristic of the preoperational stage is egocentrism. Piaget described egocentrism as a child’s inability to see things from perspectives other than their own. They assume that the rest of the world perceives things just as they do. It is demonstrated in both speech and visuospatial abilities. Speech at this age is often not directed at anyone in particular and may sound like they are thinking audibly. When asked a question, there is likely to be a lack of perspective-taking skills. For instance, if a little boy is asked if his brother has a brother, he will reply, “No.” Children at this age may also cover their eyes when they want to hide, believing that others cannot see them. In Piaget’s three-mountain task, children were not able to predict what other people saw from their vantage point even though they had previously viewed the three-mountain model from all angles. When asked what others saw, they identified what they saw from their own point of view. Piaget’s third stage of cognitive development is the concrete operational stage . It last from about 7 to 11 years and is marked by the transition from intuitive thinking to more logical or operational thought. Although operational thought is a major achievement, typically abstract or hypothetical thinking is not possible yet. Logic is limited to the application of past experiences and concrete physical phenomena (hence the name concrete operational). Still, many of the cognitive limitations of the preoperational stage are mastered during this time. For instance, children in this stage have reversibility. They learn that things can go back to their original state by reversing steps. This ability to logically follow steps and then take them in reverse order helps with performing mathematical equations and simple problem-solving. Problem-solving is also helped by the new ability of decentration. Concrete operational children can simultaneously focus on more than one salient aspect of an object, event, or action. Accordingly, the capacity for classifying and ordering information emerges. Their new multidimensional view also helps to reduce egocentrism as they learn to look at things from different perspectives. Children will also begin to master conservation. By the end of this stage, they will properly conserve liquid, number, length, mass, area, weight, and volume. At around age 11, children move into the fourth and final stage of Piaget’s theory of cognitive development. Piaget called it the formal operational stage because it is when children gain the ability to form mental representations and use them operationally. No longer are they limited to concrete thinking that requires them to test mental operations physically or rely on experience. The move from simple arithmetic to abstract algebraic equations. With this new ability to think abstractly, they also begin to contemplate concepts like love, justice, fairness, freedom, and morality. They also think about hypothetical possibilities and ideas, which often lead to reflection upon personal beliefs and identity. This coincides with the development of metacognition (thinking about thinking), with introspection typically leading to heightened self-awareness. Hypothetical- deductive reasoning becomes more important at the formal operational stage as problems are solved by formulating hypotheses and testing potential solutions. Although Piaget believed that most people gain some level of formal operational thinking by adolescence, it is not necessarily used regularly, even into adulthood. Thinking will continue to see improvements and declines with age, but the way we think fundamentally will not change in nature after this final stage. See Table 3.4 for a summary of Piaget’s stages. Table 3.4 Summary of Piaget’s Stages of Cognitive Development Stage Age Achievement Sensorimotor Birth to 18–24 months old Object permanence Preoperational 2 to 7 years old Symbolic thought Concrete operational 7 to 11 years old Concrete logic Formal operational 11 + Abstract reasoning Criticisms of Piaget’s Stage Theory Although tremendously influential, Piaget is not without his detractors. A number of criticisms have been leveled at his theory, a few of which we will briefly address here. Critics are quick to point out that sufficient evidence exists indicating that cognitive development occurs gradually rather than discretely in stages. One of the most frequently raised criticisms is that Piaget underestimated cognitive abilities, particularly in infants and young children. Since the 1970s, a large body of literature has been accumulated demonstrating that young children are far more competent than Piaget originally assumed (Lourenco & Machado, 1996; Newcombe, 2013). Likewise, he is accused of overestimating the ability for formal operational thought in adolescence and into adulthood. Formal operational thought is not universal or consistent during these periods. Another common charge is that sequential, qualitative changes in thinking between stages are not supported. Children have been documented as meeting developmental achievements from more than one stage concomitantly. Finally, Piaget has been criticized heavily for not considering the sociocultural influence on cognitive development. Piaget focused on maturation and experiences in development, but we know now that children also learn from observation and social interactions with adults and peers (Bandura, 1977; Vygotsky, 1962). Lev Vygotsky’s Sociocultural Theory of Cognitive Development Around the same time Piaget was formulating his theory, another psychologist named Lev Vygotsky was formulating his own. Although Vygotsky died before he could fully develop his theory, he made some very important contributions to the field that have been very influential in recent years. We will take a look at some of his most important ideas. Fundamental to Vygotsky’s theory is that cognitive development is socially guided. He emphasized the role of the sociocultural environment in development which was in direct opposition to Piaget, who saw experience and maturation as the primary mechanisms for cognitive development. Rather than seeing children as “little scientists, Vygotsky saw them as “apprentices” under a more skilled mentor, or what is called a more knowledgable other . The more knowledgeable other can be a parent, teacher, pastor, or peer who guides learning through instruction and modeling. Vygotsky envisioned three zones of potential development (Eun, 2019). In the first zone, the learner does not need assistance because they have already mastered a particular ability or skill. In the last zone, the learner is not capable yet of attaining an ability or skill, even with assistance. In between both is the zone of proximal development (ZPD) , where, with the guidance and support of their mentor, they can master a particular skill or ability. The guidance provided by a mentor is referred to as scaffolding . Just like construction scaffolds provide support for the worker so they can reach heights they are not capable of on their own, the mentor provides the support needed to help the apprentice attain higher mental functions , which are more complex cognitive abilities such as speech, focused attention, deliberate memory, logical thinking, and abstractions. As they are aquiring the congintive tools of their culture, such as language, symbols, morals, beliefs, values, norms, customs, manners, etc., they are also being internalized. Internalization is a process of taking what is learned through interpersonal interactions and adopting it into intrapersonal processes (inner thought life and beliefs). Language becomes the primary tool for intellectual growth as internalization manifests in inner speech (silent self-talk). Through inner speech we are able to guide and regulate our own behaviors and language, which at some point was communicated to us by mentors (Eun, 2019). Like Piaget, Vygotsgy’s theories have received a fair amount of criticism. Criticisms range from his lack of experimental testing, the minimizing of biological influences, to the vagueness of his theories. However, there is little question about the impact he made on psychology and education in his short life. Today many of his ideas guide public education. Reciprocal teaching and scaffolding are considered effective teaching strategies that are based on the application of Vygotsky’s zone of proximal development and are used extensively in classrooms. Moral Development As children develop cognitively, so does their sense of goodness, justice, and fairness. This is an important part of cognitive development and is focused on the issue of morality. Morality is defined as a system of values and beliefs that help us distinguish between right and wrong and provide our standards of behavior. When we speak of moral development , we are concerned with how these guiding principles and beliefs change throughout the lifespan. Jean Piaget understood cognitive development to be closely linked to moral development and believed children’s moral behaviors were guided and motivated by moral reasoning. He proposed two main levels of moral development. Typically, 2- to 7-year-old children have a morality of constraint , which is characterized as a rigid set of moral beliefs that cannot be broken. Rules are fixed and should be followed to avoid consequences. Piaget thought that children generally move to a morality of cooperation after age seven. Rules are much more flexible in this stage and can be changed depending on the situation. As they age, moral thinking becomes more complex and they can examine rules using reasoning, often collaborating with others to make sure that fairness prevails. Kohlberg’s Theory of Moral Development Many theories of moral development have been offered through the years, but the most prominent theorist by far is Lawrence Kohlberg. Like Piaget, he believed that cognitive development and moral development went hand and hand. Inspired by Piaget, he endeavored to find out how moral reasoning influenced moral behaviors as we get older (Kohlberg, 1969; 1976; 1978). Kohlberg is famous for using stories with ethical dilemmas to access the cognitive processes that guided moral decision-making. In his interviews of children, adolescents, and adults, he asked a series of questions about these stories to better understand how moral thinking developed. His most well-known story is the Heinz dilemma: In Europe, a woman was near death from a special kind of cancer. There was one drug that the doctors thought might save her. It was a form of radium that a druggist in the same town had recently discovered. The drug was expensive to make, but the druggist was charging ten times what the drug cost him to make. He paid $200 for the radium and charged $2,000 for a small dose of the drug. The sick woman’s husband, Heinz, went to everyone he knew to borrow the money, but he could only get together about $ 1,000 which is half of what it cost. He told the druggist that his wife was dying and asked him to sell it cheaper or let him pay later. But the druggist said: “No, I discovered the drug and I’m going to make money from it.” So Heinz got desperate and broke into the man’s store to steal the drug—for his wife. Should the husband have done that? (Kohlberg, 1963, p. 19) Using the data he collected in his interviews, Kohlberg (1971) developed three levels of morality, each consisting of two developmental stages (see Figure 3.12). As with other stage models, they progress in a fixed sequence with each stage laying the foundation for the next. How participants justify their moral decisionmaking determines in which of the six stages they are grouped, regardless of decisions. Figure 3.12 Kohlberg’s Stages of Moral Development Preconventional moral reasoning is based on rewards or punishment. Typically, this level of reasoning occurs between the ages of three and seven, but adolescents and adults can also use this type of reasoning. This level is divided into two stages. The first stage is the punishment-and-obedience orientation , where the goodness or badness of an action is determined by its consequence. Moral actions are ones that avoid punishment. The second stage is called the instrumental relativist orientation . Moral behavior is that which is personally rewarding or serves one’s needs. Sharing and reciprocity are present but are simply an exchange of favor, demonstrating an orientation toward self-interest, which is reflecting of the egocentrism that is common during this cognitivedevelopmental period (Kohlberg & Hersh, 1977). In response to the Heinz dilemma, preconventional moral thinkers may justify stealing the drug because Heinz’s wife would live, which would make Heinz happy (reward). They may disagree with stealing the drug to avoid getting arrested and going to jail (punishment). Conventional moral reasoning is the intermediate level in Kohlberg’s theory. Based on external ethics, it is characterized by conformity to familial and societal rules, regardless of consequences. Although development generally occurs between the ages of eight and 13, it remains the most common level, with many adults using conventional moral reasoning due to their orientation toward authority and rules. The conventional level of morality is divided into the following two stages: Stage 3, the interpersonal concordance (or good-boy-nice-girl orientation) , and stage 4, the “law and order” orientation . In the third stage, moral action is determined by the opinions of others. If it pleases others or receives their approval, it is considered right and good. In stage 4, morality is driven by a sense of duty, respect for authority, and maintenance of the social order. Conventional moral thinkers may respond to the Heinz dilemma by suggesting that Heinz should steal the drug because it would please his wife and receive approval from the public since the pharmacist was abusing his position and patients by overcharging. An example of a negative response would rest upon the premise that Heinz should not steal the drug because theft is illegal and socially wrong. Plus, the pharmacist has the right to charge whatever they want and can still remain moral. Postconventional moral reasoning is the final stage of Kohlberg’s theory. It is grounded in personal ethics and is characterized by a commitment to self-defined moral principles and agreed-upon societal standards, which are fallible. Stage 5 is the social-contract, legalistic orientation . In this stage, it is understood that codes of conduct are relative to the sociocultural environment and can vary. People have inherent rights and freedoms that much be balanced with public welfare and the greater good. Stage 6 is the ethical principle orientation , where moral behavior is based on universal ethical standards and abstract principles like justice, fairness, respect, and dignity. Not many adults achieve this level of moral development, but history gives us a number of postconventional moral thinkers. The great reformer Martin Luther vocally and publicly resisted the selling of indulgences by the Roman Catholic church in the 16th century; Mother Teresa actively and systematically rescued, cared for, and nurtured the rejected untouchable class in Kolkata, India; and the British humanitarian Nicholas Winton who covertly saved 669 Jewish children from Nazi-occupied Czechoslovakia during World War II (WWII) are all examples of those who could be said to have reached this level. Similarly, in the Heinz dilemma, one could argue that all people should have access to life-saving treatment regardless of its cost or availability, whereas others may reason that Heinz does not have the right to steal the drug because doing so would impinge on the pharmacist’s basic rights and freedoms. Criticisms of Kohlberg’s Stages of Moral Development Like many other pioneering theorists, Kohlberg has received some criticism for his theory of moral development. First, many question the validity of classifying moral development based on a person’s ability to articulate the justification for their moral decisions. Kohlberg has also been accused of not accounting for how variations in culture may affect moral reasoning. Critics say that his theory is reflective of an individualistic culture that emphasizes self rather than collectivistic cultures that emphasize community. Kohlberg’s theory has also been accused of being gender biased. It is presumed that women are more likely to be placed in stage 3 (interpersonal concordance or good-boy-nice-girl orientation) due to their propensity for reasoning based on their care for others and personal relationships, whereas men are more likely to reach the higher stages because of their natural inclinations for justice, fairness, and rights. Like Piaget, Kohlberg’s stages have also been criticized because it is possible to exhibit moral reasoning from several different stages simultaneously. He has also been accused of having unrealistically high expectations. Most people never move beyond stage 4, and those that do will not use postconventional moral reasoning regularly. Finally, many have complained that it is difficult to distinguish between stages 5 and 6. Kohlberg’s stages should also raise some serious concerns for Christians as well. The most salient problem with Kohlberg’s theory from a biblical perspective is that it presents morals as relative. Although a relativistic view of truth and morality is widely accepted in the prevailing culture, Christians hold the belief that the God of this universe, who is revealed in Scripture, is the moral lawgiver and our standard of what is good and right. COGNITIVE DEVELOPMENT IN ADOLESCENCE Adolescence usually brings significant improvements to cognitive abilities such as attention, processing speed, working and long-term memory, and metacognition. However, this ability improves gradually over time. In early adolescence, they may still be predominantly concrete thinkers, depending on physical experiences or tangible events and objects to make sense of the world. However, as cognition matures and formal operational thinking develops, they are less reliant on concrete thinking and more dependent on abstract thought. You will recall (see Piaget’s Formal Operational stage) that this ability to think about abstract concepts and hypothetical possibilities leads to introspection and coincides with the development of metacognitive abilities (thinking about thinking). The heightened self-awareness and self-consciousness lead to what David Elkind (1967) called adolescent egocentrism. Adolescent egocentrism , which begins in early adolescence and peaks around 14 or 15 years old, describes the tendency of adolescents to equate the thoughts and perceptions that they have about themselves to others. According to Elkind (1967), adolescent egocentrism is responsible for the belief that others are as focused on them as they are on themselves. This tendency to overestimate the attention they are receiving has them anticipating the reactions and judgments from what Elkind called the imaginary audience . Consequently, adolescents constantly react to or modify behaviors according to the mental constructs of admiration or criticism they have created for the imaginary audience. Another consequence of adolescent egocentrism is the personal fable. The personal fable refers to adolescents’ feelings of being unique or special. Their sense of importance stems from their preoccupation with self, as well as their imaginary audiences’ preoccupation with them. The personal fable also includes a sense of invulnerability and immortality. This is sometimes called the invincibility fable . Although they know that bad things happen to people, they do not think it will not happen to them because they are special. Consequently, adolescents often make poor decisions and take greater risks. Perhaps one of the most salient examples of the personal or invincibility fable is texting and driving. Driving can be difficult and dangerous for adolescents, especially when distracted. Brain activity that should be focused on driving is reduced by 37% when a cell phone is used, and it only takes a second of distraction for a crash to occur and result in life-changing consequences. According to the National Highway Traffic Safety Administration (Distracted Driving, 2017), 3,166 people were killed in distraction-affected crashes, accounting for 9% of all fatal crashes in the United States. Traffic accidents are 23 times more likely while texting, and 58% of adolescent traffic accidents occur because the driver is distracted. In fact, adolescents represent the largest group to be involved in traffic fatalities due to distractions and are three times more likely than adults to be involved in accidents with fatalities. In one study of more than 100,000 adolescent drivers, about 40% reported that they had sent an e-mail or texted while driving at least once in the past 30 days. (Li et al., 2015). Texting while driving appeared to be associated with other risky behaviors, such as not regularly wearing a seat belt and drinking alcohol while driving. Although 97% of adolescent drivers reported believing texting and driving to be dangerous, 43% of them reported doing it (Distracted Driving, 2017). Although they clearly know there is a risk, they do not think it applies to them, illustrating the personal fable that, “It won’t happen to me.” It was originally believed that adolescent egocentrism diminishes gradually through middle and late adolescence, but there is evidence indicating it continues into early adulthood. Despite any remaining egocentrism in late adolescence, emotional regulation and impulse control continue to improve, and they become more capable of accurately assessing the risks of behaviors. This is a result of the growing ability to think hypothetically and abstractly. It also helps them to plan for the future. Not only are they better equipped cognitively to think through different possibilities, but they are also able to think through logical steps that will help them reach their goals. At this point, they typically have a better sense of who they are as a person, what they believe and value, and what they…
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