According to ancient Greek legend, the Sphinx was a monster—half lion, half woman—who terrorized passersby on the road to Thebes. The Sphinx would ask each traveler a question and then murder those who failed to answer correctly. (The Sphinx was a pretty tough grader.) The question was this: What animal walks on four feet in the morning, two feet at noon, and three feet in the evening? Only one traveler, Oedipus, knew the solution to the riddle. The animal, he said, is Man, who crawls on all fours as a baby, walks upright as an adult, and limps in old age with the aid of a staff.

The Sphinx was the first lifespan theorist. Since then, many philosophers, writers, and scientists have speculated on the course of adult development. Are the changes of adulthood predictable, like those of childhood? What are the major psychological issues of adult life? Is mental and physical deterioration in old age inevitable? For some opinions on these and related questions, watch the video Different Perspectives in the World.

One of the first modern theorists to propose a lifespan approach to psychological development was psychoanalyst Erik H. Erikson (1902–1994). Erikson (1950/1963, 1982) wrote that all individuals go through eight stages in their lives. Each stage is characterized by what he called a “crisis,” a particular psychological challenge that ideally should be resolved before the individual moves on:

• Trust versus mistrust is the challenge that occurs during the baby's first year, when the baby depends on others to provide food, comfort, cuddling, and warmth. If these needs are not met, the child may never develop the essential trust of others necessary to get along in the world.

• Autonomy (independence) versus shame and doubt is the challenge that occurs when the child is a toddler. The young child is learning to be independent and must do so without feeling too ashamed or uncertain about his or her actions.

• Initiative versus guilt is the challenge that occurs as a preschooler develops. The child is acquiring new physical and mental skills, setting goals, and enjoying newfound talents, but must also learn to control impulses. The danger lies in developing too strong a sense of guilt over his or her wishes and fantasies.

• Competence versus inferiority is the challenge for school-age children, who are learning to make things, use tools, and acquire the skills for adult life. Children who fail these lessons of mastery and competence may come out of this stage feeling inadequate and inferior.

  

• Identity versus role confusion is the challenge of adolescence, when teenagers must decide who they are, what they are going to do, and what they hope to make of their lives. Erikson used the term identity crisis to describe what he considered to be the primary conflict of this stage. Those who resolve it will emerge with a strong identity, ready to plan for the future. Those who do not will sink into confusion, unable to make decisions.

• Intimacy versus isolation is the challenge of young adulthood. After you have decided who you are, said Erikson, you must share yourself with another and learn to make commitments. No matter how successful you are in your work, you are not complete until you are capable of intimacy.

• Generativity versus stagnation is the challenge of the middle years. Now that you know who you are and have an intimate relationship, will you sink into complacency and selfishness, or will you experience generativity—creativity and renewal? Parenthood is the most common route to generativity, but people can be productive, creative, and nurturant in other ways, in their work or their relationships with the younger generation.

• Ego integrity versus despair is the final challenge of late adulthood and old age. As they age, people strive to reach the ultimate goals of wisdom, spiritual tranquility, and acceptance of their lives. Just as the healthy child will not fear life, said Erikson, the healthy adult will not fear death.

Erikson's Life Stages

Erikson recognized that cultural and economic factors affect people's progression through these stages. Some societies make the passages relatively easy. If you know you are going to be a farmer like your parents and you have no alternative, you are unlikely to have an adolescent identity crisis (unless you hate farming). If you have many choices, however, or if, on the contrary, the economy has made it difficult to find any good job, the transition can become prolonged (Schwartz, 2004). Similarly, cultures that place a high premium on independence and individualism will make it difficult for many of their members to resolve Erikson's sixth crisis, that of intimacy versus isolation.

Now that people's lives have become less predictable, these psychological issues may also occur in different orders or return even after having been resolved. For example, although adolescence in Western societies is often a time of confusion about identity and aspirations, an identity crisis is not limited to the teen years. A man who has worked in one job for 20 years, and then is laid off at age 45 and must find an entirely new career, may have an identity crisis too. Likewise, competence is not mastered once and for all in childhood. People learn new skills and lose old ones throughout their lives, and their sense of competence rises and falls accordingly. And people who are highly generative, in terms of being committed to helping their communities or the next generation, tend to do volunteer work or choose occupations that allow them to contribute to society throughout their lives (McAdams, 2006). As one psychologist observed many years ago, “There is not one process of aging, but many; there is not one life course followed, but multiple courses. . . . The variety is as rich as the historic conditions people have faced and the current circumstances they experience” (Pearlin, 1982).

Stage theories, therefore, do not adequately describe how adults grow and change, or remain the same, across the lifespan. Yet Erikson was right to show that development does not stop at adolescence or young adulthood; it is an ongoing process. His ideas were influential because he placed adult development in the context of family, work, and society, and he specified many of the essential concerns of adulthood: trust, competence, identity, generativity, and the ability to enjoy life and accept death. Collectively, they reflect the timeless and universal human concerns of adulthood (Dunkel & Sefcek, 2009; Schwartz et al., 2013).

When nearly everyone your age goes through the same experience or enters a new role at the same time—going to college, having a baby, retiring—adjusting to these transitions is relatively easy. Similarly, if you aren't doing these things and hardly anyone you know is doing them either, you will not feel out of step. Today, however, most people will face unanticipated transitions—events that happen without warning, such as being fired from a job. And many people have to deal with changes that they expect to happen that do not: not getting a job after college, not getting married at the age they expected, not getting promoted, not being able to afford to retire, or realizing that they cannot have children (Schlossberg & Robinson, 1996). With this in mind, let's consider some of the major transitions of life. To begin, watch the video Identity for an overview of some major issues.

When does old age start? A few decades ago, you would have been considered old in your 60s, but that has changed. The fastest-growing segment of the population in North America now consists of people over the age of 85. There were 5.8 million Americans age 85 or older in 2012, and the Census Bureau projects that there may be as many as 18 million by 2050 (Ortman, Velkoff, & Hogan, 2014). Gerontologists, researchers who study aging and the old, have been investigating the likely consequences of this massive demographic change.

One consequence is that the phase of retirement will change significantly. When people expected to live only until their early 70s, retirement at 65 was associated with loss—a withdrawal from work and fulfilling activities, with not much to look forward to but illness and old age. Today, thanks to the enormous cohort of healthy baby boomers, retirement might last 20 or 30 years. Thus, it is no longer simply a life transition from working to not working. People in the phase of what some psychologists are calling “positive retirement” often find a new career, volunteer work, or engrossing activities (Halpern, 2008).

Nonetheless, gerontologists are concerned about this trend because various aspects of intelligence, memory, decision making, and other forms of mental functioning decline significantly with age. After roughly age 65, adults start scoring lower on tests of reasoning, spatial ability, and complex problem solving than do younger adults. It takes them longer to retrieve words and names, dates, and other information; in fact, the speed of cognitive processing in general slows down. However, older people vary in this respect, with some declining significantly and others remaining sharp (Lövdén et al., 2010; Salthouse, 2012).

Fortunately, not all cognitive abilities worsen with age. Fluid intelligence is the capacity for deductive reasoning and the ability to use new information to solve problems. It reflects in part an inherited predisposition, and it parallels other biological capacities in its growth and later decline (Bosworth & Schaie, 1999; Li et al., 2004; Opitz et al., 2014). Crystallized intelligence consists of knowledge and skills built up over a lifetime, the kind of intelligence that gives us the ability to do arithmetic, define words, or take political positions. It depends heavily on education and experience, and it tends to remain stable or even improve over the lifespan. This is why physicians, lawyers, teachers, farmers, musicians, insurance agents, politicians, psychologists, and people in many other occupations can continue working well into old age (Halpern, 2008). Also, older adults are often able to compensate for age-related declines by recruiting parts of the brain that are not commonly activated when young people do the same tasks—an example of the brain's impressive plasticity (flexibility) (Huang et al., 2012).

Many of the physical and mental losses that do occur in old age are physiologically and genetically based and are seen in all societies, but others have to do with cultural, behavioral, and psychological factors (Park & Gutchess, 2006). Psychologists have made great strides in separating conditions previously thought to be an inevitable part of old age from those that are preventable or treatable:

• Apparent senility in older adults is often caused by malnutrition, prescription medications, harmful combinations of medications, and over-the-counter drugs (such as sleeping pills and antihistamines), all of which can be hazardous to older people.

• Weakness, frailty, and even many of the diseases associated with old age are often caused by being inactive and sedentary (Booth & Neufer, 2005).

• Depression, passivity, and memory problems may result from the loss of meaningful activity, intellectual stimulation, goals to pursue, and control over events (Hess, 2005; Schaie & Zuo, 2001).

Older people can profit from aerobic exercise and strength training, which maintain physical strength and flexibility, boost the brain's blood supply, and promote the development of new cells in the hippocampus and other areas of the brain. The result is improved functioning in memory, planning, concentration, and making schedules (Colcombe & Kramer, 2003; Erickson et al., 2011; Hertzog et al., 2008). Mental stimulation also fosters the growth of neural connections in the brain, even well into old age. Cognitive enrichment cannot prevent most cases of serious cognitive decline and dementia, but the declines may be delayed (Bozzali et al., 2015; Gatz, 2007; Hertzog et al., 2008).

Perhaps the best news is that as people get older, most become better able to regulate negative feelings and emphasize the positive. The frequency of intense negative emotions is highest among people aged 18 to 34, then drops sharply to age 65. After 65, it levels off, rising only slightly among old people facing crises of illness and bereavement (Charles & Carstensen, 2004; Opitz et al., 2014; Urry & Gross, 2010). Apparently, many people do grow wiser, or at least more tranquil, with age.

Famous Adults

Some researchers who study aging are therefore optimistic. In their view, people who have challenging occupations and interests, who remain active mentally, who exercise regularly, and who adapt flexibly to change and loss are more likely than others to maintain their cognitive abilities and well-being. “Use it or lose it,” they say, and they are hopeful that research into the brain's remarkable plasticity will one day produce successful interventions to prevent or delay cognitive decline (Lövdén et al., 2010). In a study of people who were 100 years old at the start of the investigation, fully 73 percent of them were free of dementia at the time of their deaths (in one case, at age 111) (Hagberg & Samuelsson, 2008). Why? Genome-wide association studies are beginning to identify the specific molecular circuits that are associated with good memory in some very old individuals such as these (Barnes, 2011). Other gerontologists are less upbeat. “When you've lost it, you can't use it,” they reply. They are worried about the growing numbers of people living into their 90s and beyond, when rates of cognitive impairment and dementia rise dramatically (Salthouse, 2006). The challenge for society is to prepare for the many people who will be living into advanced old age, by helping as many as possible to keep using their brains instead of losing them.