Periods of Development

File photo. The Developmental Stages of a Child (Online Psychology Degree Guide, 2021)

Some of these changes are biologically driven, which menas they are caused by genes or physiology, and some are environmentally driven, meaning they are influenced by things in the person’s environment, including parents, siblings, peers, and neighborhoods; most changes are the product of the interactions between biology and environment.

Although developmental psychologists and developmental cognitive neuroscientists who study adolescence mainly focus on individuals who are adolescents, they appreciate that understanding the developmental periods that precede and follow adolescence is equally important. In general, there are three developmental periods: childhood, adolescence, and adulthood.

Childhood

Childhood is comprised of the prenatal period, infancy, early childhood, and late childhood.

• The prenatal period is the development that occurs from the point of conception until birth. In humans, this period lasts approximately 9 months and is a time of significant growth: the organism morphs from a single cell to one complete with all the organs it will ever have in its lifetime. During this time, there is complete dependence on the mother for nutrients.
• Infancy encompasses the period from birth through approximately 18 months of age. Many important psychological activities and much physical learning occur during this time and there is extreme dependence on adult caregivers. Infants engage in active sensorimotor coordination, gross motor skill learning (e.g. walking), language learning, and intense social engagement, particularly period between parent and child.

• Early childhood is the developmental period that follows the end of infancy and extends through about 5 – 6 years of age (approximately when a child enrolls in kindergarten). During this time, there is a focus on becoming more self-sufficient, as children begin to spend many hours playing alone and with peers. It is also during this time that they begin more complex language and reading skills.
• Middle & late childhood is the developmental period that extends from about kindergarten to right before adolescence (10 or 11 years of age). Significant academic learning occurs during this time, as children become more engaged in the fundamental skills of reading, writing, and arithmetic. Self-regulation of behavior increases during this time.

Adolescence

Given all the learning, skill emergence, and social interactions that occur prior to adolescence, childhood sets up adolescents with a rich developmental history. The combination of genetic background and childhood developmental history contributes to the course of adolescent development and associated brain development during this time. This is important to remember as we learn about the changes that occur during adolescence.

Adolescent researchers face a daunting task in deciding how to define the “adolescent” group in their research studies. Most scientists have identified adolescence as “the gradual period of transition from childhood to adulthood” (Spear, 2000). Some neuroscience studies on human adolescents define adolescence by age, grade level, or pubertal status.

The exact timing of adolescence is not as clear-cut as that of childhood because its definition encompasses multiple factors. The age range of adolescence also varies with cultural and historical circumstances. In the United States, adolescence begins at approximately 11 to 13 years of age and ends in the late teenage years (approximately 18 – 19 years of age).

• Early adolescence typically encompasses the period from the middle school years and includes most of the pubertal development that characterizes the early part of adolescence.
• Late adolescence refers approximately to the period after the majority of the pubertal transitition. Significant psychosocial and cognitive changes occur during this time, including increases in orientation toward peers, romantic interests, and identity exploration, as well as more sophisticated cognitive abilities, including abstract thought, future planning and goal setting, and career exploration.

Adulthood

Similar to childhood and adolescence, adulthood is a heterogenous period of development that is not characterized by any one behavior or developmental milestone. It is the period of development that spans the greatest number of years as it includes early, middle, and lage adulthood.

• Early adulthood (sometimes referred to as emerging adulthood: Arnett, 2011) refers to the late adolescent years and early 20s and lasts through the mid-30s. This period of life is very important in establishing complete financial and personal independence and is often when individuals attend college away from home as well as focus on career development. There is also a high prevalence of marriage in the late 20s.
• Middle adulthood begins at approximately 35 to 40 years of age and ends at some point between approximately 55 and 65 years of age. This period is when most child-rearing occurs, as individuals in this age group tend to have children undergoing childhood or adolescence.
• Late adulthood is the developmental period that lasts from approximately 65 years of age until death. In the United States, the average life expectancy is 77.4 and 82.2 for males and females, respectively.

Ways of Studying Development

Developmental psychologists have a variety of strategies with which to study development. These various strategies can be subdivided into two broad, interrelated categories — designs that enable us to study age-related changes in behavior, and the associated research methods that are used to collect the information or data about development. These are discussed under the next two broad headings — Designs for studying age-related changesOpens in new window and Research methods, which include observational studiesOpens in new window, experimental methodsOpens in new window, psychological testingOpens in new window, and correlational studiesOpens in new window.