Lifespan Development. Tara L. Kuther

of contextual factors that interact over the life course can be organized into three categories: age-graded influences, history-graded influences, and nonnormative influences (Elder & George, 2016; Elder, Shanahan, & Jennings, 2016).

      Age-graded influences are closely tied to chronological age and are largely predictable. Most individuals walk at about a year of age and reach puberty in early adolescence. Similarly, most women reach menopause in the late 40s or early 50s. Age-graded influences tend to be most influential early and late in life. Although these influences are often tied to biology, social milestones can also form age-graded influences. Most people in the United States enter school at about 5 years of age, graduate high school and enter college at about age 18, and retire during their 60s. Some age-graded influences are context dependent. For example, adolescents in suburban and rural contexts commonly get driver’s licenses at age 16, but this may not be true of adolescents in urban settings where driving may be less common.

      History-graded influences refer to how the time period in which we live and the unique historical circumstances of that time period affect our development. Examples of history-graded influences include wars, epidemics, advances in science and technology, and economic shifts such as periods of depression or prosperity (Baltes, 1987). Contextual influences tied to particular historical eras explain why a generation of people born at the same time, called a cohort, is similar in ways that people born at other times are different. For example, 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; they tend to have particularly strong views on the importance of the family, civic mindedness, and social connection (Rogler, 2002).

      Cultural Influences on Development

      Defining Culture

      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

      We are embedded in culture, a 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 (Markus & Kitayama, 1991). 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 (Mistry & Dutta, 2015).

      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. Yet research that defines normative development based on Western samples 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 (Cole & Packer, 2015).

      Developmental norms vary by cultural context (Schweder et al., 1998). Biology and culture are inseparable, and the cultural context in which individuals live influences the timing and expression of many aspects of development (Mistry, 2013). 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 in 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).

      There is a growing trend favoring cultural research, which examines how culture itself influences development, over cross-cultural research, which simply examines differences across cultures (Cole & Packer, 2015). Cultural research examines development and culture as fused entities that mutually interact, with culture inherent in all domains of development and a contributor to the context in which we are embedded, transmitting values, attitudes, and beliefs that shape our thoughts, beliefs, and behaviors (Mistry & Dutta, 2015). The shift toward cultural research permits the examination of the multiple subcultures that exist within a society (Oyserman, 2016, 2017). For example, North American culture is not homogeneous; 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. Current trends in cultural research document diversity and emphasize understanding how the historical, cultural, and subcultural contexts in which we live influence development throughout our lives.

      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?

      Take a moment to think about what role larger historical events have played in your development. For example, consider the costly and deadly 2017 Hurricanes Harvey, Irma, and Maria. The mass flooding destroyed homes and businesses in Texas, the southeastern United States, and Puerto Rico and killed thousands of people. Other examples of historical events include the terrorist attacks of September 11, 2001; the election of the first African American president of the United States in 2008; the school shooting in Newtown, Connecticut, in 2012; and the legalization of same-sex marriage in 2015. How have historical events influenced you and those around you? Can you identify ways in which, because of historical events, your cohort may differ from your parents’ cohort?

      Whereas age-graded and history-graded influences are common to all people or all members of a cohort, individuals also have experiences that are unique to them. Nonnormative influences are experiences or events that happen to a person or a few people. Examples of nonnormative influences include experiencing the death of a parent in childhood, widowhood in early adulthood, winning the lottery, or illness. Nonnormative events are not predictable and are not easily studied, as they are not experienced by most peopl—and the nature of nonnormative events varies widely. With age, nonnormative influences become more powerful determinants of development.

      Developmental Science Is Multidisciplinary

      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 (Holmes, Kim-Spoon, & Deater-Deckard, 2016), and neurological development (Ullman, Almeida, & Klingberg, 2014)—findings from the fields of medicine, psychology, and neuroscience, respectively. To understand how people develop at all periods in life, developmental scientists must combine insights from all of these 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 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 has the context in which you were raised and live influenced 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 worldview, and their