Lifespan Development. Tara L. Kuther

or jumping movements may walk earlier (Siekerman et al., 2015; Worobey, 2014).

      Although developmental scientists once attempted to determine whether development depended on nature or nurture, most now agree that both nature and nurture are important contributors (Rutter, 2014; Sasaki & Kim, 2017). Thus, walking is heavily influenced by maturation (nature), but experiences and environmental conditions can influence the timing of a child’s first steps (nurture). Today developmental scientists attempt to determine how nature and nurture interact and work together to influence how people grow and change throughout life (Bjorklund, 2018; Lickliter & Witherington, 2017).

      To review, the three basic questions regarding lifespan human development are as follows:

      1 Is developmental change gradual, showing continuity, or abrupt, illustrating discontinuity?

      2 What role do people play in their own development—how much are they influenced by their surroundings and how much do they influence their surroundings?

      3 To what extent is development a function of heredity, and to what extent is it a function of the environment in which individuals live?

      Developmental scientists vary in their responses to these questions, as we will see throughout this book.

      Thinking in Context 1.2

      1 Can you identify ways in which you have changed very gradually over the years? Were there other times in which you showed abrupt change, such as physical growth, strength and coordination, thinking abilities, or social skills? In other words, in what ways is your development characterized by continuity? Discontinuity?

      2 What role did your physical and social environment play in your growth? In what ways, if any, did you take an active role in your own development?

      3 How much of who you are today is a function of nature? Nurture?

      Theoretical Perspectives on Human Development

      Over the past century, scientists have learned much about how individuals progress from infants, to children, to adolescents, and to adults, as well as how they change throughout adulthood. Developmental scientists explain their observations by constructing theories of human development. A theory is a way of organizing a set of observations or facts into a comprehensive explanation of how something works. Theories are important tools for compiling and interpreting the growing body of research in human development as well as determining gaps in our knowledge and making predictions about what is not yet known.

      Effective theories generate specific hypotheses, or proposed explanations for a given phenomenon, that can be tested by research. It is important to note that this testing seeks to find flaws in the hypothesis—not to “prove” that it is flawless. A good theory is one that is falsifiable, or capable of generating hypotheses that can be tested and, potentially, refuted. As scientists conduct research and learn more about a topic, they modify their theories. Updated theories often give rise to new questions and new research studies, whose findings may further modify theories.

      The great body of research findings in the field of lifespan human development has been organized into several theoretical perspectives. As the following sections illustrate, these theoretical perspectives vary greatly in how they account for the developmental changes that occur over the lifespan.

      Sigmund Freud (1856–1939), the father of the psychoanalytic perspective, believed that much of our behavior is driven by unconscious impulses.

      Wikimedia

      Psychoanalytic Theories

      Are there powerful forces within us that make us behave as we do? Are we pushed by inner drives? Psychoanalytic theories describe development and behavior as a result of the interplay of inner drives, memories, and conflicts we are unaware of and cannot control. These inner forces influence our behavior throughout our lives. Freud and Erikson are two key psychoanalytic theorists whose theories remain influential today.

      Freud’s Psychosexual Theory

      Sigmund Freud (1856–1939), a Viennese physician, is credited as the father of the psychoanalytic perspective. Freud believed that much of our behavior is driven by unconscious impulses that are outside of our awareness. As shown in Table 1.2, Freud believed we progress through a series of psychosexual stages, periods in which unconscious drives are focused on different parts of the body, making stimulation to those parts a source of pleasure. Freud explained that the task for parents is to strike a balance between overgratifying and undergratifying a child’s desires at each stage to help the child develop a healthy personality with the capacity for mature relationships throughout life. Notably, Freud did not study children; his theory grew from his work with female psychotherapy patients (Crain, 2016).

      In part because of its heavy emphasis on childhood sexuality, Freud’s psychosexual stage framework, especially the phallic stage, is not widely accepted (Westen, 1998). Yet many of Freud’s ideas have stood up well to the test of time and have permeated popular culture. These ideas include the notion of unconscious processes of which we are unaware, the importance of early family experience, and the role of emotions in development (Bargh, 2013). Another reason why Freud’s theory tends to be unpopular with developmental scientists is that it cannot be directly tested and is therefore not supported by research (Miller, 2016). How are we to study unconscious drives, for instance, when we are not aware of them?

      Erikson’s Psychosocial Theory

      Erik Erikson (1902–1994) was influenced by Freud, but he placed less emphasis on unconscious motivators of development and instead focused on the role of the social world, society, and culture. Erikson posed a lifespan theory of development, as shown in Table 1.3. According to this theory, individuals progress through eight psychosocial stages that include changes in how they understand and interact with others, as well as changes in how they understand themselves and their roles as members of society (Erikson, 1950) (see Table 1.3). Each stage presents a unique developmental task, which Erikson referred to as a crisis or conflict that must be resolved. How well individuals address the crisis determines their ability to deal with the demands made by the next stage of development.

Table 1.2

      Regardless of their success in resolving a crisis of a given stage, individuals are driven by biological maturation and social expectations to the next psychosocial stage. No crisis is ever fully resolved, and unresolved crises are revisited throughout life. Although Erikson believed that it is never too late to resolve a crisis, resolving a crisis from a previous stage may become more challenging over time as people focus on current demands and the crises of their current psychosocial stages.

      Erik Erikson (1902–1994) posited that, throughout their lives, people progress through eight stages of psychosocial development.

      Jon Erikson/Science Source

      Erikson’s psychosocial theory is well regarded as one of the first lifespan views of development. He took a positive view of development and included the role of society and culture by basing his theory on a broad range of cases, including larger and more diverse samples of people than did Freud. Erikson’s theory is criticized as difficult to test, but it has nonetheless sparked research on specific stages, most notably on the development of identity during adolescence