Understanding Psychology (10th Ed)

 
Module 38 
Adolescence: Becoming an Adult 
413
feelings cause curiosity, interest, and sometimes embarrassment for individuals 
entering adolescence. 
The physical changes that occur at the start of adolescence result largely from 
the secretion of various hormones, and they affect virtually every aspect of an ado-
lescent’s life. Not since infancy has development been so dramatic. Weight and height 
increase rapidly because of a growth spurt that typically begins around age 10 for 
girls and age 12 for boys. Adolescents may grow as much as 5 inches in one year. 
 Puberty,  the period at which maturation of the sexual organs occurs, begins at 
about age 11 or 12 for girls, when menstruation starts. However, there are wide 
variations (see Figure 1). For example, some girls begin to menstruate as early as age 
8 or 9 or as late as age 16. Furthermore, in Western cultures, the average age at which 
adolescents reach sexual maturity has been steadily decreasing over the last century 
most likely as a result of improved nutrition and medical care. Sexual attraction to 
others begins even before the maturation of the sexual organs at around age 10 (see 
Figure 1; Tanner, 1990; Finlay, Jones, & Coleman, 2002).
 
For boys, the onset of puberty is marked by their fi rst ejaculation, known as 
spermarche . Spermarche usually occurs around the age of 13 (see Figure 1). At fi rst, 
relatively few sperm are produced during an ejaculation, but the amount increases 
signifi cantly within a few years. 
The age at which puberty begins has implications for the way adolescents feel 
about themselves—as well as the way others treat them. Early-maturing boys have 
a distinct advantage over later-maturing boys. They do better in athletics, are gener-
ally more popular with peers, and have more positive self-concepts (Ge et al., 2003; 
Becker & Luthar, 2007). 
puberty
The period at which matura-
tion of the sexual organs occurs, 
beginning at about age 11 or 12 for 
girls and 13 or 14 for boys.
FIGURE 1
The range of ages during 
which major sexual changes occur during 
adolescence is shown by the colored 
bars. 
(Source: Based on Tanner, 1978.)
11 
10 14 
12 15 
13 16 
17 
18 
Age (years) 
Pubic hair 
First 
ejaculation 
Penis growth 
Height spurt 
Average male
11
10
14
12
15
13
16
17
18
Age (years)
Pubic hair
Breast
development
Onset of
menstruation
Height spurt
Average female
feL82795_ch12_378-435.indd Page 413 7/31/10 12:52 AM user-f465
feL82795_ch12_378-435.indd Page 413 7/31/10 12:52 AM user-f465
/Users/user-f465/Desktop
/Users/user-f465/Desktop

---