Prompt: Every one of us has many experiences in his or her lifetime. Talk about an experience in your life (from childhood until today) that you feel impacted your developm

1 Understanding Human Development: Approaches and Theories

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Learning Objectives 1.1 Outline five principles of the lifespan developmental perspective. 1.2 Discuss three theoretical controversies about human development. 1.3 Summarize five theoretical perspectives on human development. 1.4 Describe the methods used in studying human development, including types of data and designs. 1.5 Discuss the responsibility of researchers to their participants and how they may protect them.

Digital Resources

Resilience: It Takes a Village

Poverty and Brain Development

Second Couplehood in Late Adulthood

Nature and Nurture

Educational Aspirations

Sociocultural Influences on Development: Desegregation

Children of Katrina: Longitudinal Research

Childhood Exposure to Lead

Voluntary Participation in HIV Research

Master these learning objectives with multimedia resources available at edge.sagepub.com/kuthertopical and Lives in Context video cases available in the interactive eBook.

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Think back over your lifetime. How have you grown and changed through the years? Do your parents describe you as a happy baby? Were you fussy? Do you remember your first day of kindergarten? What are some of your most vivid childhood memories? Did you begin puberty early, late, or was your development similar to others your age? Were your adolescent years a stressful time? What types of changes do you expect to undergo in your adult years? Where will you live? Will you have a spouse? Will you have children? What career will you choose? How might these life choices and circumstances influence how you age and your perspective in older adulthood? Will your personality remain the same or change over time? In short, how will you change over the course of your lifespan?

What is Lifespan Human Development? This is a book about lifespan human development—the ways in which people grow, change, and stay the same throughout their lives, from conception to death. When people use the term development, they often mean the transformation from infant to adult. However, development does not end with adulthood. We continue to change in predictable ways throughout our lifetime, even into old age. Developmental scientists study human development. They seek to understand lifetime patterns of change.

lifespan human development An approach to studying human development that examines ways in which individuals grow, change, and stay the same throughout their lives, from conception to death.

Table 1.1 illustrates the many phases of life that we progress through from conception to death. Each phase of life may have a different label and set of developmental tasks, but all have value. The changes that we undergo during infancy influence how we experience later changes, such as those during adolescence and beyond. This is true for all ages in life. Each phase of life is important and accompanied by its own demands and opportunities.

Change is the most obvious indicator of development. The muscle strength and coordination needed to play sports increases over childhood and adolescence, peaks in early adulthood, and begins to decline thereafter,

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declining more rapidly from middle to late adulthood. Similarly, children’s capacity to learn and perform cognitive tasks increases as they progress from infancy through adolescence, and adults typically experience a decline in the speed of cognitive processing. However, there also are ways in which we change little over our lifetimes. Some personality traits, for example, are highly stable over the lifespan, so that we remain largely the “same person” into old age (McCrae, 2002; Roberts & Caspi, 2003; Wortman, Lucas, & Donnellan, 2012).

Table 1.1 Ages in Human Development Table 1.1 Ages in Human Development

Life Stage Approximate

Age Range Description

Prenatal Conception to birth

Shortly after conception, a single- celled organism grows and multiplies. This is the most rapid period of physical development in the lifespan as basic body structures and organs form and grow. The fetus hears, responds to sensory stimuli (such as the sound of its mother’s voice), learns, remembers, and begins the process of adjusting to life after birth.

Infancy and toddlerhood

Birth to 2 years

The newborn is equipped with senses that help it to learn about the world. Environmental influences stimulate the brain to grow more complex, and the child interacts with her environment, shaping it. Physical growth occurs as well as the development of motor, perceptual, and intellectual skills. Children show advances in language comprehension and use, problem solving, self- awareness, and emotional control. They become more independent and

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interested in interacting with other children and form bonds with parents and others.

Early childhood

2 to 6 years

Children grow steadily over these years of play prior to beginning elementary school. Children’s muscles strengthen, and they become better at controlling and coordinating their bodies. Children’s bodies become more slender and adultlike in proportions. Memory, language, and imagination improve. Children become more independent and better able to regulate their emotions as well as develop a sense of right and wrong. Children become more aware of their own characteristics and feelings. Family remains children’s primary social tie, but other children become more important and new ties to peers are established.

Middle childhood 6 to 11 years

Growth slows, and health tends to be better in middle childhood than at any other time during the lifespan. Strength and athletic ability increase dramatically. Children show improvements in their ability to reason, remember, read, and use arithmetic. As children advance cognitively and gain social experience, they understand themselves and think about moral issues in more complex ways as compared with younger children. As friendships develop, peers and group memberships become more important

Adolescents’ bodies grow rapidly.

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Adolescence 11 to 18 years

They become physically and sexually mature. Though some immature thinking persists, adolescents can reason in sophisticated and adultlike ways. Adolescents are driven to learn about themselves and begin the process of discovering who they are, apart from their parents. Most adolescents retain good relationships with parents, but peer groups increase in importance. Adolescents and their peers influence each other reciprocally. It is through adolescents’ interactions with family and peers that they begin to establish a sense of who they are.

Early adulthood

18 to 40 years

In early adulthood, physical condition peaks and then shows slight declines with time. Lifestyle choices, such as smoking, diet, and physical activity, play a large role in influencing health. As they enter early adulthood, young adults experience

a great many changes, such as moving out of the family home, going to college, establishing mature romantic relationships, and beginning careers. Young adults’ understanding of themselves is complex and shifts as they experience life changes and take on new responsibilities and new roles. Young adults make and carry out decisions regarding career, lifestyle, and intimate relationships. Most young adults join the workforce, marry or establish a long-term bond with a spouse, and become parents. The timing of these transitions varies, but most fully enter adult roles by the

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mid-20s. Some developmental scientists define a transitional period between adolescence and early adulthood, referred to as emerging adulthood, which represents the period between completing secondary education and adopting adult roles, such as work and family. Emerging adulthood spans ages 18 to 25, or even as late as age 29; however, not all young people experience a period of emerging adulthood as not all are embedded in contexts that permit a gradual transition to adulthood.

Middle adulthood

40 to 65 years

In middle adulthood, people begin to notice changes in their vision, hearing, physical stamina, and sexuality. Basic mental abilities, expertise, and practical problem- solving skills peak. Career changes and family transitions require that adults continue to refine their understandings of themselves. Some adults experience burnout and career changes while others enjoy successful leadership positions and increased earning power at the peak of their careers. Stress stems from assisting children to become independent, adapting to an empty nest, and assisting elderly parents with their health and personal needs.

Most older adults remain healthy and active despite physical declines. Reaction time slows, and most older adults show decline in some aspects of memory and intelligence, but an increase in expertise and wisdom compensates for losses. Most older

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Late adulthood

65 years and beyond

adult friendships are old friendships, and these tend to be very close and a source of support. At the same time, older adults are less likely to form new friendships than at other times in life. They face adjustments to retirement, confront decreased physical health and strength, cope with personal losses (such as the death of a loved one), think about impending death, and search for meaning in their lives.

Death

Death itself is a process. Regardless of whether it is sudden and unexpected, the result of a lengthy illness, or simply old age, death entails the stopping of heartbeat, circulation, breathing, and brain activity. A person’s death causes changes in his or her social context— family members and friends must adjust to and accept the loss.

Lifespan human development can be described by several principles. As discussed in the following sections, development is: (1) multidimensional, (2) multidirectional, (3) plastic, (4) influenced by multiple contexts, and (5) multidisciplinary (Baltes & Carstensen, 2003; Baltes, Lindenberger, & Staudinger, 1998; Baltes, 1997).

Development Is Multidimensional Physical changes such as body growth are the most obvious forms of development. Not only do our bodies change, but so do our minds, the ways in which we show emotion, and our social relationships. In this way, development is multidimensional: It entails changes in many areas of development, including the physical, the cognitive, and the socioemotional (Baltes et al., 1998; Baltes, 1997; Staudinger & Lindenberger, 2003). Physical development refers to body maturation and growth, including body size, proportion, appearance, health, and perceptual abilities.

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Cognitive development refers to the maturation of thought processes and the tools that we use to obtain knowledge, become aware of the world around us, and solve problems. Socioemotional development includes changes in personality, emotions, views of oneself, social skills, and interpersonal relationships with family and friends. Each of these areas of development overlap and interact. With advances in cognitive development, for example, a child may become better able to take her best friend’s point of view, which in turn influences her socioemotional development as she becomes more empathetic and sensitive to her friend’s needs and develops a more mature friendship. Figure 1.1 illustrates these three areas of development and how they interact.

physical development Body maturation, including body size, proportion, appearance, health, and perceptual abilities.

cognitive development Maturation of mental processes and tools individuals use to obtain knowledge, think, and solve problems.

socioemotional development Maturation of social and emotional functioning, which includes changes in personality, emotions, personal perceptions, social skills, and interpersonal relationships.

Figure 1.1: Multidimensional Nature of Development

Advances in physical, cognitive, and socioemotional development interact, permitting children to play sports, learn more efficiently, and develop close friendships.

iStock/Essentials

iStock/Signature

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Jupiter/Pixland/Thinkstock

Development Is Multidirectional Development is commonly described as a series of improvements in performance and functioning, but in fact development is multidirectional, meaning that it consists of both gains and losses, growth and decline, throughout the lifespan (Baltes et al., 1998; Baltes, 1997; Staudinger & Lindenberger, 2003). For example, we are born with a stepping reflex, an innate involuntary response in which infants make step-like movements when held upright over a table, bed, or hard horizontal surface (for more on infant reflexes, see Chapter 4). Over the first year, infants gain new motor skills and the stepping reflex disappears (Thelen, Fisher, & Ridley- Johnson, 2002). As another example of multidirectionality, in older adulthood people’s social networks narrow and they have fewer friends; however, their relationships become more significant and meaningful (Carstensen & Mikels, 2005). Throughout life there is a shifting balance between gains and improvements in performance (common early in life) and losses and declines in performance (common late in life; Baltes & Carstensen, 2003). At all ages, however, individuals can compensate for losses by improving existing skills and developing new ones (Boker, 2013; Freund & Baltes, 2007). For example, though the speed at which people think tends to slow in older adulthood, increases in knowledge and experience enable older adults to compensate for the loss of speed, so that they generally retain their ability to complete day-to-day tasks and solve everyday problems (Bluck & Gluck, 2004; Hess, Leclerc, Swaim, & Weatherbee, 2009; Margrett, Allaire, Johnson, Daugherty, & Weatherbee, 2010). Outside of our awareness, the brain naturally adapts to a lifetime of sensory experiences in order to portray the world around us efficiently and accurately as we age well into older adulthood (Moran, Symmonds, Dolan, & Friston, 2014).

Development Is Plastic Development is characterized by plasticity: It is malleable or changeable. Frequently the brain and body can compensate for illness and injury. Children who are injured and experience brain damage may show resilience as other parts of the brain take on new functions. The plastic nature of human development allows people to modify their traits,

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capacities, and behavior throughout life (Baltes et al., 1998; Baltes, 1997; Staudinger & Lindenberger, 2003). For example, older adults who have experienced a decline in balance and muscle strength can regain and improve these capabilities through exercise (McAuley et al., 2013). Plasticity generally tends to decline as we age, but it does not disappear entirely. Short instruction, for instance, can enhance the memory capacities of very old adults, but less so than younger adults (Singer, Lindenberger, & Baltes, 2003). Thus, memory plasticity is preserved, but to a reduced degree, in very old age. Plasticity makes it possible for individuals to adjust to change and to demonstrate resilience, which is the capacity to adapt effectively to adverse contexts and circumstances (Luthar et al., 2015; Masten, 2016).

plasticity A characteristic of development that refers to malleability, or openness to change in response to experience.

resilience The ability to adapt to serious adversity.

Some plasticity is retained throughout life. Practicing athletic activities can help older adults rebuild muscle and improve balance.

Reuters/Mike Blake

Development Is Influenced by Multiple Contexts In its simplest terms, context refers to where and when a person develops. Context includes aspects of the physical and social environment such as family, neighborhood, country, culture, and historical time period. Context also includes intangible factors, characteristics that are not visible to the

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naked eye, such as values, customs, and ideals. Culture is a particularly important context that influences us, as illustrated in Cultural Influences on Development: Defining Culture.

context Unique conditions in which a person develops, including aspects of the physical and social environment such as family, neighborhood, culture, and historical time period.

In order to understand a given individual’s development, we must look to his or her context. For example, consider the context in which you were raised. Where did you grow up? City? Suburb? Rural area? What was your neighborhood like? Were you encouraged to be assertive and actively question the adults around you, or were you expected to be quiet and avoid confrontation? How large a part was religion in your family’s life? How did religious values shape your parent’s child-rearing practices and your own values? How did your family’s economic status affect your development?

An important context that influences our development is the time period in which we live. Some contextual influences are tied to particular historical eras and explain why a generation of people born at the same time, called a cohort, are similar in ways that people born at other times are different. History-graded influences include wars, epidemics, and economic shifts such as periods of depression or prosperity (Baltes, 1987). These influences shape our development and our views of the world—and set cohorts apart from one another. Adults who came of age during the Great Depression and World War II are similar in some ways that make them different from later cohorts; for example, they tend to have particularly strong views on the importance of the family, civic mindedness, and social connection (Rogler, 2002). Age-graded influences, those tied to chronological age, such as the age at which the average person enters school, reaches puberty, graduates from high school, gets married, or has children, are also shaped by context as the normative age of each of these events has shifted over the last few generations (Baltes, 1987).

cohort A generation of people born at the same time, influenced by the same historical and cultural conditions.

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What roles have larger historical events played in your development? For example, consider Hurricane Sandy of October 2012, the second costliest hurricane in U.S. history, which affected 24 states, including the entire eastern seaboard, with flooding, downed power lines, and many destroyed homes. Historical events include the terrorist attacks of September 11, 2001; the election of the first African American president of the United States in 2008; and the school shooting in Newtown, Connecticut in 2012. How have historical events influenced you and those around you? Can you identify ways in which your cohort differs from your parents’ cohort because of historical events?

Developmental Science Is Multidisciplinary To say that people are complex is an understatement. Scientists who study lifespan human development attempt to understand people’s bodies, minds, and social worlds. The contributions of many disciplines are needed to understand how people grow, think, and interact with their world. Psychologists, sociologists, anthropologists, biologists, neuroscientists, and medical researchers all conduct research that is relevant to understanding aspects of human development. For example, consider cognitive development. Children’s performance on cognitive measures, such as problem solving, are influenced by their physical health and nutrition (Anjos et al., 2013), interactions with peers (Fawcett & Garton, 2005; Holmes, Kim-Spoon, & Deater-Deckard, 2016), and neurological development (Ullman, Almeida, & Klingberg, 2014)— findings from the fields of medicine, psychology, and neuroscience, respectively. In order to understand how people develop at all periods in life, developmental scientists must combine insights from all of these disciplines.

Cultural Influences on Development

Defining Culture

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Cultural influences on development are illustrated by the many ethnic communities that comprise most U.S. cities. What subcultures and neighborhoods can you identify in your community?

Reuters/Lucy Nicholson

A large and influential part of our context is culture, which is the set of customs, knowledge, attitudes, and values that are shared by members of a group and are learned early in life through interactions with group members (Hofstede, 2001). Most classic theories and research on human development are based on Western samples, and developmental researchers once believed that the processes of human development were universal. Early studies of culture and human development took the form of cross-cultural research, comparing individuals and groups from different cultures to examine how these universal processes worked in different contexts (Gardiner & Kosmitzki, 2002).

More recently we have learned that the cultural context in which individuals live influences the timing and expression of many aspects of development (Gardiner & Kosmitzki, 2002). For example, the average age that infants begin to walk varies with cultural context. In Uganda, infants begin to walk at about 10 months of age, in France at about 15 months, and the United States at about 12 months. These differences are influenced by parenting practices that vary by culture. African parents tend to handle infants in ways that stimulate walking, by playing games that allow infants to practice jumping and walking skills (Hopkins & Westra, 1989; Super, 1981). Developmental researchers have argued that because much of the research in human development has focused on individuals from Western industrialized societies, there is a danger of defining typical development in Western samples as the norm, which can lead to narrow views of human development that do not take into account the variety of contexts in which people live. At the extreme, differences in human development within other cultural groups might be viewed as abnormal (Rogoff & Morelli, 1989). Some argue that cross-cultural research that compares the development of people from different cultures in order to understand universals in development is misguided because norms vary by cultural context (Schweder et al.,

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1998).

There is a growing trend favoring cultural research, which examines how culture influences development, over cross-cultural research, which simply examines differences among cultures (Schweder et al., 1998). From a cultural research perspective, culture influences our development because it contributes to the context in which we are embedded, transmitting values, attitudes, and beliefs that shape our thoughts, beliefs, and behaviors (Cole, 1999). The shift toward cultural research permits the examination of the multiple cultures that exist within a society. For example, North American culture is not homogenous; many subcultures exist, defined by factors such as ethnicity (e.g., African American, Asian American), religion (e.g., Christian, Muslim), geography (e.g., southern, Midwestern), and others, as well as combinations of these factors. Instead of looking for universal similarities in development, cultural research in human development aims to document diversity and understand how the historical and cultural context in which we live influences development throughout our lifetime (Schweder et al., 1998).

What Do You Think? 1. How would you describe North American culture? Can you

identify aspects of North American culture that describe most, if not all, people who live there? Are there aspects of culture in which people or subgroups of people differ?

2. What subcultures can you identify in your own neighborhood, state, or region of the country? What characterizes each of these subcultures?

3. Consider your own experience. With which culture or subculture do you identify? How much of a role do you think your cultural membership has had in your own development?

culture A set of customs, knowledge, attitudes, and values shared by a group of people and learned through interactions with group members.

The field of lifespan human development studies the ways in which people grow, change, and stay the same throughout their lives. Human

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development is complex. We change in multiple ways, show gains and losses over time, and retain the ability to change over our lifespan. The context in which we live influences who we become. Developmental science incorporates research from multiple disciplines.

Thinking in Context 1.1

1. Describe your own development. In what ways have you changed over your lifetime? What characteristics have remained the same?

2. Lifespan human development is multidimensional, multidirectional, plastic, and influenced by multiple contexts. Consider your own experience and provide examples from your life that illustrate the multidimensional nature of your own development. Can you do the same for multidirectionality and for plasticity? How does the context in which you were raised and live influence your development?

3. Compare the historical context in which you, your parents, and your grandparents were raised. How did historical and societal influences affect your grandparents’ development, their world view, and their child-rearing strategies? What about your parents? How might historical influences affect your own development, world view, and perspective on parenting?

Basic Issues in Lifespan Human Development Developmental scientists agree that people change throughout life and show increases in some capacities and decreases in others from conception to death. Yet, how development proceeds, the specific changes that occur, and the causes of change are debated. Developmental scientists’ explanations of how people grow and change over their lives are influenced by their perspectives on three basic issues, or fundamental questions, about human development:

1. Do people remain largely the same over time, or do they change dramatically?

2. What role do people play in their own development? How much are they influenced by their surroundings, and how much do they

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influence their surroundings? 3. To what extent is development a function of inborn genetic

endowments, as compared with the environment in which individuals live?

The following sections examine each of these questions.

Continuities and Discontinuities in Development Do children slowly grow into adults, steadily gain more knowledge and experience, and become better at reasoning? Or do children grow in spurts, showing sudden and large gains in knowledge and reasoning capacities? In other words, in what ways is developmental change continuous, characterized by slow and gradual change, or discontinuous, characterized by abrupt change? As shown in Figure 1.2, a discontinuous view of development emphasizes sudden transformation in abilities and capacities whereas a continuous view emphasizes the gradual and steady changes that occur. Scientists who argue that development is continuous in nature point to slow and cumulative changes we experience in the amount or degree of skills, such as a child slowly gaining experience, expanding his or her vocabulary, and becoming quicker at problem solving, or a middle-aged adult experiencing gradual losses of muscle and strength. The discontinuous view of development describes the changes we experience as large and abrupt, with individuals of various ages dramatically different from one another. For example, puberty quickly transforms children’s bodies into more adult-like adolescent bodies, infants’ understanding and capacity for language is fundamentally different from that of school-aged children, and children make leaps in their reasoning abilities over the course of childhood (Piek, Dawson, Smith, & Gasson, 2008). For example, children progress from believing that robotic dogs and other inanimate objects are alive to understanding that life is a biological process (Gelman & Opfer, 2002).

continuous development The view that development consists of gradual cumulative changes in existing skills and capacities.

discontinuous development The view that growth entails abrupt transformations in abilities and capacities in which new ways of interacting with the world emerge.

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Figure 1.2: Continuous and Discontinuous Development

It was once believed that development was either continuous or discontinuous—that changes were either slow and gradual or sudden and dramatic—but not both. Today, developmental scientists agree that development includes both continuity and discontinuity (Kagan, 2008; Lerner, Agans, DeSouza, & Gasca, 2013; Miller, 2016). Whether a particular developmental change appears continuous or discontinuous depends on our point of view. For example, consider human growth. We often think of increases in height as a slow and steady process of simply getting taller with time; each month infants are taller than the prior month, illustrating continuous change. However, as shown in Figure 1.3, when researchers measured infants’ height every day they discovered that infants have growth days and non-growth days, days that they show rapid change in height interspersed with days in which there is no change in height, thus illustrating discontinuous change (Lampl, Johnson, Frongillo Jr., & Frongillo, 2001; Lampl, Veldhuis, & Johnson, 1992). In this example, monthly measurements of infant height suggest gradual increases, but daily measurements show spurts of growth, each lasting 24 hours or less. In this way, whether a given phenomenon, such as height, is described as continuous or discontinuous can vary. Most developmental scientists agree that some aspects of lifespan development are best described as continuous and others as discontinuous (Miller, 2016).

Figure 1.3: Infant Growth: A Continuous or Discontinuous Process?

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Infants’ growth occurs in a random series of roughly 1-centimeter spurts in height that occur in 24 hours or less. The overall pattern of growth entails increases in height, but whether the growth appears to be continuous or discontinuous depends on our point of view.

Source: Figure 1 from Lampl, M., Veldhuis, J. D., & Johnson, M. L. 1992. Saltation and stasis: A model of human growth. Science, 258, 801–803. With permission from AAAS.

Individuals Are Active in Development Do people have a role in influencing how they change over their lifetimes? That is, are people active in influencing their own development? Taking an active role means that they interact with and influence the world around them, create experiences that lead to developmental change, and thereby influence how they themselves change over the lifespan. Alternatively, if individuals take a passive role in their development, they are shaped by, but do not influence, the world around them—including home and relationships with family, school, and neighborhood characteristics, such the availability of playgrounds or health care.

Infants naturally influence people and the world around them. What rea

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