Developmental psychologists generally adopt one of two approaches to studying human development. Some developmental psychologists focus on the changes and influences that occur during specific stages of life. This “ages and stages” approach typically divides the life course into eight age-related periods. These are (1) the prenatal period, from conception to birth; (2) infancy, from birth to age 2; (3) early childhood, ages 2 to 6; (4) middle childhood, ages 6 to 12; (5) adolescence, ages 12 to 19; (6) early adulthood, ages 19 to 40; (7) middle adulthood, ages 40 to 60; and (8) late adulthood, ages 60 and beyond. Researchers using this approach study how development unfolds within each stage. Such a strategy reveals how developmental changes within each stage relate to each other—such as how cognitive growth facilitates social understanding in young children—but it sometimes neglects how these influences are maintained from one stage to the next.
The other main approach to the study of human development focuses on specific aspects of development across the life span. This “topical” approach divides human development into different areas of growth, including physical, cognitive, social, emotional, and personality development. Such an approach enables scientists to understand how certain influences, such as emotional attachments to others, are important throughout life. However, it sometimes focuses on one aspect of development to the neglect of others. Thus, each approach has advantages and disadvantages.
This article discusses some of the major topics that developmental psychologists study. These are physical development, cognitive development, social and emotional development, personality development, and moral development.
A Physical Development
The study of physical development focuses on the growth of the brain, body, and physical capabilities, along with the psychological implications of this growth. Early in life, the brain and body grow remarkably in size and sophistication, leading to rapid increases in sensory ability and muscular strength and coordination. These changes provide a foundation for equally remarkable advances in cognition, emotion, and sociability. Late in life, health problems and physical changes may lead to declines in mental speed and other abilities and to changes in mood and sociability.
Scientists are discovering, however, that physical development throughout life does not produce inevitable psychological changes. Rather, the psychological effect of physical changes is largely determined by the way in which an individual interprets and responds to them. One example is the influence of puberty on adolescents. Despite society’s perception that hormonal changes in puberty cause adolescent turmoil, self-consciousness, and rebelliousness, careful studies of adolescents reveal that the psychological impact of puberty depends on a variety of factors. These include the timing of puberty (whether it is early or late in relation to peers), cultural values about the meaning of sexual maturity (including media portrayals of adolescence), and the warmth of family relationships, especially the relationship between the teenager and the parent of the same sex.
Although physical development usually proceeds normally, a variety of environmental factors can adversely affect it. Poor nutrition, exposure to harmful viruses, drugs, and environmental hazards (including lead and pesticides), and enduring physical stress can imperil healthy growth beginning from conception. Maintaining good health promotes optimal physical and psychological growth throughout life.
B Cognitive Development
Cognitive development concerns the growth of the mind throughout life. One of the challenges of studying cognitive development is that there are so many aspects of mental growth, including the development of memory, perception, logical reasoning, problem-solving skill, numerical understanding, intelligence, and hypothetical thinking. Language development includes the development of vocabulary, grammar, the pragmatics of language use, and bilingualism. Brain development, or developmental neuroscience, is another major topic of study.
The questions that guide research on cognitive development vary depending on the age group being studied. Studies of infancy investigate how very young children, whose minds are still quite immature, can effortlessly achieve so much understanding of the world. Are innate learning processes at work? Is rapid brain growth the reason? Developmental psychologists use cleverly designed experiments to explore what infants know and when and how they achieve understanding. Studies of older adults explore how the mind adapts to the changes in sensory ability and mental speed that accompany aging. Do some features of mental functioning improve in later life while others decline? Can older adults avoid or reverse age-related changes in mental functioning through changes in lifestyle or through training? To answer such questions, researchers are studying the mental performance of older adults with different backgrounds and lifestyles.