Understanding Psychology (10th Ed)

380

Prologue
Twice-Born Baby 
Keri and Chad McCartney were looking forward to learning 
whether their baby was a boy or a girl. But the moment an image 
swam onto the screen at a Texas doctor’s offi
ce last February 15, 
the technician fell silent. When Keri, 40, and Chad, 39, a pastor, 
peered closer, they saw a bulge below the fetus. “What’s that?” 
they asked. “Well, it’s a mass,” came the answer. 
Then Dr. Debra Williams delivered diffi
cult news: The tailbone 
attachment was a rare tumor, present in 1 of 35,000 pregnancies, 
that draws on the fetal blood supply. The baby’s odds of survival? 
Less than 10%. (Smolowe, 2008, p. 96) 

Looking
Ahead 

But Keri and Chad’s daughter Marcie did survive. In a risky inter-
vention, surgeons temporarily removed their daughter from Keri’s 
uterus and cut out most of the tumor. They then put her back 
into her mother’s body to fi nish developing normally until she 
fi nally could be delivered—a second time—ten weeks later. 
The medical advances that permitted Marcie to survive are 
just some of the many that have improved children’s lives, not 
only in the prenatal period but throughout their life span. Marcie’s 
story also serves as an introduction to one of the broadest and 
most important areas of psychology: developmental psychology. 
Developmental psychology is the branch of psychology that 
studies the patterns of growth and change that occur through-
out life. It deals with issues ranging from new ways of conceiving 
children, to learning how to raise children most sensibly, to 
understanding the milestones of life that we all face. 
Developmental psychologists study the interaction between 
the unfolding of biologically predetermined patterns of behavior 
and a constantly changing, dynamic environment. They ask how 
our genetic background aff ects our behavior throughout our 
lives and whether heredity limits our potential. Similarly, they 
seek to understand the way in which the environment works 
with—or against—our genetic capabilities, how the world we 
live in aff ects our development, and how we can be encouraged 
to reach our full potential. 
We begin by examining the approaches psychologists use to 
study development change across the life span. Then we consider 
the very start of development, beginning with conception and 
the nine months of life before birth. We look at both genetic and 
environmental infl uences on the unborn individual and the way 
they can aff ect behavior throughout the remainder of the life 
cycle. 
Next, we examine development that occurs after birth: the 
enormous and rapid growth that takes place during the early 
stages of life and the physical, social, and cognitive change 
throughout infancy, toddlerhood, and middle childhood. We 
then move on to development from adolescence through 
adulthood. We end with a discussion of the ways in which 
people prepare themselves for death.
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381
How many bald, six-foot-six, 250-pound volunteer fi refi ghters in New Jersey wear 
droopy mustaches, aviator-style eyeglasses, and a key ring on the right side of the 
belt? The answer is two: Gerald Levey and Mark Newman. They are twins who were 
separated at birth. Each twin did not even know the other existed until they were 
reunited—in a fi re station—by a fellow fi refi ghter who knew Newman and was startled 
to see his double, Levey, at a fi refi ghters’ convention. 
The lives of the twins, although separate, took remarkably similar paths. Levey 
went to college and studied forestry; Newman planned to study forestry in college 
but instead took a job trimming trees. Both had jobs in supermarkets. One had a job 
installing sprinkler systems; the other installed fi re alarms. 
Both men are unmarried and fi nd the same kind of woman—“tall, slender, long 
hair”—attractive. They share similar hobbies and enjoy hunting, fi shing, going to the 
beach, and watching old John Wayne movies and professional wrestling. Both like 
Chinese food and drink the same brand of beer. Their mannerisms are also similar—
for example, each one throws his head back when he laughs. And, of course, there is 
one more thing: They share a passion for fi ghting fi res. 
The similarities we see in twins Gerald Levey and Mark Newman vividly raise one 
of the fundamental questions posed by  developmental psychology,  the study of the 
patterns of growth and change that occur throughout life. The question is this: How 
can we distinguish between the environmental causes of behavior (the infl uence of 
parents, siblings, family, friends, schooling, nutrition, and all the other experiences 
to which a child is exposed) and hereditary causes (those based on an individual’s 
genetic makeup that infl uence growth and development throughout life)? This ques-
tion embodies the  nature–nurture issue.  In this context, nature refers to hereditary 
factors, and nurture refers to environmental infl uences.

Although the question was fi rst posed as a nature- versus-

nurture issue, developmental psychologists today agree that 
both nature and nurture interact to produce specifi c develop-
mental patterns and outcomes. Consequently, the question has 
evolved into this: How and to what degree do environment and 
heredity both produce their effects? No one develops free of 
environmental infl uences or without being affected by his or 
her inherited genetic makeup . However, the debate over the 
comparative infl uence of the two factors remains active; dif-
ferent approaches and different theories of development 
emphasize the environment or heredity to a greater or lesser 
degree (Gottesman & Hanson, 2005; Rutter, 2006; Belsky & 
Pluess, 2009). 
For example, some developmental theories rely on basic 
psychological principles of learning and stress the role learn-
ing plays in producing changes in a developing child’s behav-
ior. Such theories emphasize the role of the environment in 
development. In contrast, other developmental theories 
emphasize the infl uence of one’s physiological makeup and