Lifespan Development
KEY POINTS
Introduction: Your Life Story
Developmental psychologists study the many ways in which people change over the lifespan. Key themes in developmental psychology include understanding the stages of lifespan development, the nature of change, and the interaction between heredity and environment. Research in developmental psychology may incorporate either a longitudinal design or a cross-sectional design.
Genetic Contributions to Your Life Story
At conception, the union of the sperm and egg result in the single-celled zygote. The zygote contains genetic instructions inherited from the biological parents, encoded in the chromosomes. Chromosomes are made of deoxyribonucleic acid (DNA). Each chromosome has thousands of DNA segments called genes, which encode instructions for making a particular protein.
An organism’s unique genotype is found in almost every body cell. Cells differ not because they carry different genes but because they result from different genes being activated or expressed. Mapping of the human genome resulted in the discovery that humans have only 20,000–
The phenotype results from the interaction of genes and environmental factors. Different genotypes respond differently to the same environmental factors. Epigenetics is the study of the factors that control gene expression.
Prenatal Development
During the nine months that make up the prenatal stage, the zygote develops into a full-term fetus. The prenatal stage includes the germinal period, the embryonic period, and the fetal period. Stem cells can divide indefinitely and give rise to other types of cells. The greatest vulnerability to teratogens occurs during the embryonic stage, when major bodily systems are forming.
Development During Infancy and Childhood
Newborns are equipped with reflexes and sensory capabilities that enhance their chances for survival. Vision, hearing, and smell are attuned to interaction with caregivers. The brain develops rapidly after birth. The sequence of motor skill development is generally universal, although there is individual variation in the rate of development.
Thomas and Chess demonstrated that infants seem to be born with different temperaments. They identified three basic temperamental patterns: easy, difficult, and slow-to-warm-up. According to Kagan, infants can be classified in terms of reactivity. Temperamental qualities seem to have a biological basis and persist through life, although they can be modified by environmental influences.
According to attachment theory, the infant’s ability to thrive is dependent on the quality of his or her attachment to caregivers. Secure attachment develops when parents are sensitive and responsive to the infant’s needs. Insecure attachment may develop when parents are insensitive to the infant’s needs.
Infants are biologically predisposed to learn language. Adults encourage language development in infants by using motherese, also called parentese or infant-directed speech.
The stages of language development include cooing, babbling, the one-word stage, and the two-word stage. At every stage, comprehension vocabulary is larger than production vocabulary.
Cognitive Development
According to Jean Piaget’s theory of cognitive development, children progress through distinct cognitive stages, each of which represents a shift in how they think and understand the world.
Object permanence is acquired during the sensorimotor stage. Symbolic thought is acquired during the pre-operational stage. Preoperational thought is egocentric and characterized by irreversibility and centration. Thus, the preoperational child is unable to grasp the principle of conservation. Children become capable of logical thought during the concrete operational stage, but thinking is limited to tangible objects and events. During the formal operational stage, the adolescent can engage in logical mental operations involving abstract concepts and hypothetical situations.
Criticisms of Piaget’s theory include the following: Piaget underestimated the cognitive abilities of infants and children; he underestimated the impact of the social and cultural environment on cognitive development; and he overestimated the degree to which people achieve formal operational thought processes. In contrast to Piaget’s theory, Vygotsky’s idea of the zone of proximal development emphasizes that children can progress to higher cognitive levels through the assistance of others who are more competent.
The information-processing model is a description of cognitive development that emphasizes basic mental processes and stresses that cognitive development is a process of continuous change.
Adolescence
During adolescence, puberty occurs. Puberty involves the development of primary and secondary sex characteristics, the adolescent growth spurt, and, in females, menarche. While the sequence of pubertal changes is relatively predictable, the timing of puberty varies. Factors that affect the timing of puberty include gender, nutrition, body weight, family stress, and absence of the biological father.
In general, when parent–
Erik Erikson’s theory of psychosocial development stresses that every stage of life is marked by a particular psychosocial conflict. Identity versus role confusion is the conflict associated with adolescence; however, the process of identity formation does not end in adolescence.
Lawrence Kohlberg described the types of moral reasoning used in making moral decisions. His theory of moral development includes the preconventional, conventional, and postconventional levels; each level has two stages. Other researchers study the role of emotion, culture, and gender in moral decision making.
Adult Development
Although there are general patterns in adult development, individual variation becomes increasingly significant. The three phases of adulthood are early adulthood, middle adulthood, and late adulthood. Genetics, environment, and an individual’s lifestyle all influence physical changes during adulthood and aging. Women experience menopause and men experience andropause during middle adulthood as the production of sex hormones declines in both sexes.
Love and work are two key themes that dominate adult development. Friends continue to be important in adulthood. Forming a committed, intimate relationship is one important task traditionally associated with early adulthood.
Marital satisfaction tends to decline after the first child is born and to increase after children leave home. Family structures and relationships have become increasingly diverse in the United States.
Late Adulthood and Aging
Late adulthood does not necessarily involve a steep decline in physical and cognitive functioning. Mental abilities begin to decline slightly only at around age 60, and these declines can be minimized or eliminated with an active and mentally stimulating lifestyle.
Many older adults do not disengage from life but remain socially active. According to the activity theory of aging, life satisfaction in late adulthood is highest when people maintain their previous levels of activity. Older adults differ in their optimal level of activity. Erikson identified ego integrity versus despair as the key psychosocial conflict of old age.
The Final Chapter: Dying and Death
Although commonly associated with old age, death can occur at any point in the lifespan. Anxiety about death tends to peak in middle adulthood and decrease in late adulthood. Elisabeth Kübler-Ross proposed a five-stage model of dying: denial, anger, bargaining, depression, and acceptance. However, individuals respond in diverse ways to impending death.
Match each of the terms on the left with its definition on the right. Click on the term first and then click on the matching definition. As you match them correctly they will move to the bottom of the activity.
activity theory of aging adolescence adolescent growth spurt attachment authoritarian parenting style authoritative parenting style centration chromosome comprehension vocabulary concrete operational stage conservation cross-sectional design deoxyribonucleic acid (DNA) developmental psychology egocentrism embryonic period emerging adulthood epigenetics fetal period formal operational stage gene genotype germinal period identity induction information-processing model of cognitive development irreversibility longitudinal design menarche menopause moral reasoning object permanence permissive parenting style phenotype prenatal stage preoperational stage primary sex characteristics production vocabulary puberty secondary sex characteristics sensorimotor stage sex chromosomes stem cells symbolic thought temperament teratogens zone of proximal development zygote | In Piaget's theory, the understanding that two equal quantities remain equal even though the form or appearance is rearranged, as long as nothing is added or subtracted. The first two weeks of prenatal development. A discipline technique that combines parental control with explaining why a behavior is prohibited. Research strategy in which individuals of different ages or developmental stages are directly compared. The double-stranded molecule that encodes genetic instructions; the chemical basis of heredity. The aspect of cognitive development that has to do with how an individual reasons about moral decisions. Parenting style in which parents are demanding and unresponsive toward their children's needs or wishes. Harmful agents or substances that can cause malformations or defects in an embryo or fetus. In Piaget's theory, the inability to take another person's perspective or point of view. The stage of development before birth; divided into the germinal, embryonic, and fetal periods. In Piaget's theory, the inability to mentally reverse a sequence of events or logical operations. The natural cessation of menstruation and the end of reproductive capacity in women. In industrialized countries, the stage of lifespan from approximately the late teens to the mid-to late-20s, which is characterized by exploration, instability, and flexibility in social roles, vocational choices, and relationships. The ability to use words, images, and symbols to represent the world. The observable traits or characteristics of an organism as determined by the interaction of genetics and environmental factors. The psychosocial theory that life satisfaction in late adulthood is highest when people maintain the level of activity they displayed earlier in life. The stage of adolescence in which an individual reaches sexual maturity and becomes physiologically capable of sexual reproduction. Chromosomes, designated as X or Y, that determine biological sex; the 23rd pair of chromosomes in humans. A unit of DNA on a chromosome that encodes instructions for making a particular protein molecule; the basic unit of heredity. Sexual organs that are directly involved in reproduction, such as the uterus, ovaries, penis, and testicles. A long, thread-like structure composed of twisted parallel strands of DNA; found in the cell nucleus. The single cell formed at conception from the union of the egg cell and sperm cell. The third and longest period of prenatal development, extending from the ninth week until birth. In Piaget's theory, the first stage of cognitive development, from birth to about age 2; the period during which the infant explores the environment and acquires knowledge through sensing and manipulating objects. The genetic makeup of an individual organism. In Piaget's theory, the third stage of cognitive development, which lasts from about age 7 to adolescence; characterized by the ability to think logically about concrete objects and situations. The model that views cognitive development as a process that is continuous over the lifespan and that studies the development of basic mental processes such as attention, memory, and problem solving. A person's sense of self, including his or her memories, experiences, and the values and beliefs that guide his or her behavior. The emotional bond that forms between an infant and caregiver(s), especially his or her parents. The period of accelerated growth during puberty, involving rapid increases in height and weight. The understanding that an object continues to exist even when it can no longer be seen. Research strategy in which a variable or group of variables are studied in the same group of participants over time. Undifferentiated cells that can divide and give rise to cells that can develop into any one of the body's different cell types. The words that an infant or child understands and can speak. Inborn predispositions to consistently behave and react in a certain way. In Piaget's theory, the tendency to focus, or center, on only one aspect of a situation and ignore other important aspects of the situation. The words that are understood by an infant or child. Parenting style in which parents set clear standards for their children's behavior but are also responsive to their children's needs and wishes. Sexual characteristics that develop during puberty and are not directly involved in reproduction but differentiate between the sexes, such as male facial hair and female breast development. In Piaget's theory, the fourth stage of cognitive development, which lasts from adolescence through adulthood; characterized by the ability to think logically about abstract principles and hypothetical situations. The second period of prenatal development, extending from the third week through the eighth week. A female's first menstrual period, which occurs during puberty. The transitional stage between late childhood and the beginning of adulthood, during which sexual maturity is reached. The study of the cellular mechanisms that control gene expression and of the ways that gene expression impacts health and behavior. In Vygotsky's theory of cognitive development, the difference between what children can accomplish on their own and what they can accomplish with the help of others who are more competent. The branch of psychology that studies how people change over the lifespan. Parenting style in which parents are extremely tolerant and not demanding; permissive-indulgent parents are responsive to their children, but permissive-indifferent parents are not. In Piaget's theory, the second stage of cognitive development, which lasts from about age 2 to age 7; characterized by increasing use of symbols and prelogical thought processes. |
Mary D. Salter Ainsworth (1913–
Renée Baillargeon (b. 1954) Canadian-born psychologist whose studies of cognitive development during infancy—using visual rather than manual tasks—challenged beliefs about the age at which object permanence first appears. (p. 372)
Erik Erikson (1902–
Lawrence Kohlberg (1927–
Jean Piaget (1896–
Lev Vygotsky (1896–