Adolescent Development: Learn It 1—Physical Growth During Adolescence

  • Describe the physical, cognitive, and emotional development that occurs during adolescence
  • Describe Kohlberg’s theory of moral development and the stages of reasoning
  • Discuss Hamlin and Wynn’s research on moral reasoning in infants

Adolescence is a socially constructed concept. In pre-industrial society, children were considered adults when they reached physical maturity, but today we have an extended time between childhood and adulthood called adolescence.

adolescence

Adolescence is the period of development that begins at puberty and ends at emerging adulthood, or into the mid- to late 20s. In the United States, adolescence is seen as a time to develop independence from parents while remaining connected to them (Figure 1). The typical age range of adolescence is from 12 to 18 years, and this stage of development also has some predictable physical, cognitive, and psychosocial milestones.

A photograph captures four people midair as they hold hands and jump.
Figure 1. Peers are a primary influence on our development in adolescence. (credit: “manseok_Pixabay”/ Pixabay)

Physical Development

As noted above, adolescence begins with puberty. While the sequence of physical changes in puberty is predictable, the onset and pace of puberty vary widely. Several physical changes occur during puberty, such as:

  • adrenarche and gonadarche, the maturing of the adrenal glands and sex glands, respectively.
  • Also during this time, primary and secondary sexual characteristics develop and mature. Primary sexual characteristics are organs specifically needed for reproduction, like the uterus and ovaries in females and testes in males. Secondary sexual characteristics are physical signs of sexual maturation that do not directly involve sex organs, such as the development of breasts and hips in girls, and the development of facial hair and a deepened voice in boys.
  • Girls experience menarche, the beginning of menstrual periods, usually around 12–13 years old, and boys experience spermarche, the first ejaculation, around 13–14 years old.
  • During puberty, both sexes experience a rapid increase in height (i.e., growth spurt). For girls this begins between 8 and 13 years old, with adult height reached between 10 and 16 years old. Boys begin their growth spurt slightly later, usually between 10 and 16 years old, and reach their adult height between 13 and 17 years old. Both nature (i.e., genes) and nurture (e.g., nutrition, medications, and medical conditions) can influence height.

Because rates of physical development vary so widely among teenagers, puberty can be a source of pride or embarrassment. Early maturing boys tend to be stronger, taller, and more athletic than their later maturing peers. They are usually more popular, confident, and independent, but they are also at a greater risk for substance abuse and early sexual activity (Flannery, Rowe, & Gulley, 1993; Kaltiala-Heino, Rimpela, Rissanen, & Rantanen, 2001). Early maturing girls may be teased or overtly admired, which can cause them to feel self-conscious about their developing bodies. These girls are at a higher risk for depression, substance abuse, and eating disorders (Ge, Conger, & Elder, 2001; Graber, Lewinsohn, Seeley, & Brooks-Gunn, 1997; Striegel-Moore & Cachelin, 1999). Late blooming boys and girls (i.e., they develop more slowly than their peers) may feel self-conscious about their lack of physical development. Negative feelings are particularly a problem for late maturing boys, who are at a higher risk for depression and conflict with parents (Graber et al., 1997) and more likely to be bullied (Pollack & Shuster, 2000).

The adolescent brain also remains under development.

Recall from your earlier study that the brain consists of six regions: temporal lobe, brain stem, cerebellum, occipital lobe (includes the visual cortex), parietal lobe, and the frontal lobe. The frontal lobe consists of the prefrontal cortex, premotor cortex, and motor cortex. The prefrontal lobe lies just behind the forehead.
An illustration of a brain is shown with the frontal lobe labeled.
Figure 2. Brain growth continues into the early 20s. The development of the frontal lobe, in particular, is important during this stage.

Up until puberty, brain cells continue to bloom in the frontal region. Adolescents engage in increased risk-taking behaviors and emotional outbursts possibly because the frontal lobes of their brains are still developing (Figure 2). Recall that this area is often called the “CEO of the brain”, as it is responsible for judgment, impulse control, and planning. It is still maturing into early adulthood, up until around age 25 (Casey, Tottenham, Liston, & Durston, 2005).

Brain maturity occurs when there is growth of new neural connections and the pruning of unused neurons and connections. According to recent research, the brain regions tend to develop from the back to the front of the brain. Also, myelin continues to grow around axons and neurons helping to speed transmission between the various regions of the brain.