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Most would agree that parenting is a lifelong job. The parent’s obligations begin once the baby is conceived and seemingly never end, even after his or her child becomes an adult.

Suppose that you are the parent in each of the following scenarios. Based on what you have learned from this unit’s materials, answer the following questions for each scenario by explaining how you would effectively handle each situation.

Note: While it is understood different people and even entire cultures have different parenting styles, your answers should be based on the research and theories presented in this unit.

Describe the stage of cognitive development of the child in each scenario.

Explain how you would address the child and the situation. Will you use punishment in any of the situations? What tactics would be the most useful considering your child’s level of cognitive development?

Scenario 1: Jimmy screams when the batteries die on his Avengers motorcycle. Previously, his mother had been able to put the motorcycle away and have Jimmy immediately engage in playing with something else. However, she has noticed that he is not doing that this time. He continues to scream even though the motorcycle has been put in a drawer. As his parent, how would you respond?

Scenario 2: An 8-year-old boy and his 10-year-old brother are told to share three cans of soda pop. The 8-year-old becomes angry when his 10-year-old brother takes two of the cans and gives the 8-year-old only one can. The 10-year-old grabs two glasses and pours one soda into the two glasses and gives it to the 8-year-old. Everything is fine now as they both have two soda pop drinks. How do you address each child?

Scenario 3: Your 21-year-old daughter comes home from college and excitedly shares that she is quitting school to invest more time in her social media career. In fact, she reveals that she will be quitting school, despite only having 1 year left to complete her bachelor’s degree. (She does not see the need for her degree any longer, as her Instagram followers have increased exponentially since she has begun doing some of the popular Tik Tok challenges.) She has decided to throw away her former career plans and become a full-time social media influencer. Now, her life is all set! (What is your reaction?)

8.1–8.3 Studying Human
What is development? In the context of life, human development is the scientific study of
the changes that occur in people as they age, from conception until death. This chapter
will touch on almost all of the topics covered in the other chapters of this text, such as
personality, cognition, biological processes, and social interactions. But here, all of
those topics will be studied in the context of changes that occur as a result of the
process of human development.
human development
the scientific study of the changes that occur in people as they age from conception until
8.1 Research Designs
1. 8.1 Compare and contrast the special research methods used to study development.
As briefly discussed in Chapter One, research in human development is affected by the problem
of age. In any experiment, the participants who are exposed to the independent variable (the
variable in an experiment that is deliberately manipulated by the experimenter) should be
randomly assigned to the different experimental conditions. The challenge in developmental
research is that the age of the people in the study should always be an independent variable, but
people cannot be randomly assigned to different age groups.
There are some special designs that are used in researching age-related changes: the longitudinal
design, in which one group of people is followed and assessed at different times as the group
ages; the cross-sectional design, in which several different age groups are studied at one time;
and the cross-sequential design, which is a combination of the longitudinal and cross-sectional
designs (Baltes et al., 1988; Schaie & Willis, 2010).
longitudinal design
research design in which one participant or group of participants is studied over a long
period of time.
cross-sectional design
research design in which several different participant age-groups are studied at one
particular point in time.
cross-sequential design
research design in which participants are first studied by means of a cross-sectional
design but are also followed and assessed longitudinally.
The longitudinal design has the advantage of looking at real age-related changes as those
changes occur in the same individuals. Disadvantages of this method are the lengthy amount of
time, money, and effort involved in following participants over the years, as well as the loss of
participants when they move away, lose interest, or die. The cross-sectional design has the
advantages of being quick, relatively inexpensive, and easier to accomplish than the longitudinal
design. Its main disadvantage is that the study no longer compares an individual to that same
individual as he or she ages; instead, individuals of different ages are being compared to one
another. Differences between age groups are often a problem in developmental research. For
example, if comparing the IQ scores of 30-year-olds to 80-year-olds to see how aging affects
intelligence, questions arise concerning the differing educational experiences and opportunities
those two age groups have had that might affect IQ scores, in addition to any effects of aging.
This is known as the cohort effect, the particular impact on development that occurs when a
group of people share a common time period or common life experience (for example, having
been born in the same time period or having gone through a specific historical event
together). Table 8.1 shows a comparison between examples of a longitudinal design, a crosssectional design, and a cross-sequential design.
cohort effect
the impact on development occurring when a group of people share a common time
period or common life experience.
Table 8.1
A Comparison of Three Developmental Research Designs
Cross-Sectional Design
Different participants of various ages are compared at one point in time to determine age-related differences.
Longitudinal Design
The same participants are studied at various ages to determine age-related changes.
Cross-Sequential Design
Different participants of various ages are compared at several points in time to determine both age-related differenc
related changes.
Cross-Sectional Design
In studying human development, developmental psychologists have outlined many theories of
how these age-related changes occur. There are some areas of controversy, however, and one of
these is the issue of nature versus nurture.
8.2 Nature and Nurture
1. 8.2 Explain the relationship between heredity and environmental factors in determining
Nature refers to heredity, the influence of inherited characteristics on personality, physical
growth, intellectual growth, and social interactions. Nurture refers to the influence of the
environment on all of those same things and includes parenting styles, physical surroundings,
economic factors, and anything that can have an influence on development that does not come
from within the person.
the influence of our inherited characteristics on our personality, physical growth,
intellectual growth, and social interactions.
the influence of the environment on personality, physical growth, intellectual growth, and
social interactions.
So is a person like Hitler born that way, or did something happen to make him the person he was?
How much of a person’s personality and behavior is determined by nature and how much is
determined by nurture? This is a key question, and the answer is quite complicated. It is also
quite important: Are people like Hitler or Nikolas Cruz (the 20-year-old who killed seventeen
students and staff members and wounded seventeen more at Marjory Stoneman Douglas High
School in Parkland, Florida, on February 14, 2018) the result of bad genes, bad parenting, or lifealtering experiences in childhood? How much of Stephen Hawking’s genius was due to his
genetic inheritance? What part did the parenting choices of his family play? Or were his
cognitive abilities the unique combination of both hereditary and environmental influences?
After many years of scientific research, most developmental psychologists now agree that the
last possibility is the most likely explanation for most of human development: All that people are
and all that people become is the product of an interaction between nature and nurture (Davis et
al., 2012; Insel & Wang, 2010; Polderman et al., 2015; Ridley, 1999; Sternberg &
Grigorenko, 2006; Ursini et al., 2018). This does not mean that the nature versus nurture
controversy no longer exists; for example, intelligence is still a “hot topic” with regard to how
much is inherited and how much is learned. Some researchers and theorists assume a large
genetic influence (Bouchard & Segal, 1985; Herrnstein & Murray, 1994; Jensen,
1969; Johnson et al., 2007; Kristensen & Bjerkedal, 2007), whereas many others believe that
culture, economics, nutrition in early childhood, and educational opportunities have a greater
impact (Gardner et al., 1996; Gould, 1996; Rose et al., 1984; Wahlsten, 1997).
Behavioral genetics is a field of study in which researchers try to determine how much of
behavior is the result of genetic inheritance and how much is due to a person’s experiences. As
the video Family and Twin Studies explains, behavioral geneticists use a variety of methods to
determine this, including family, twin, and adoption studies.
Family and Twin Studies
8.3 The Basic Building Blocks of Development
1. 8.3 Summarize the role of chromosomes and genes in determining the transmission of
traits and the inheritance of disorders.
Any study of the human life span must begin with looking at the complex material contained in
the cells of the body that carries the instructions for life itself. After discussing the basic building
blocks of life, we will discuss how the processes of conception and the development of the infant
within the womb take place.
Chromosomes, Genes, and DNA
Genetics is the science of heredity. Understanding how genes transmit human characteristics and
traits involves defining a few basic terms.
the science of inherited traits.
DNA (deoxyribonucleic acid) is a very special kind of molecule (the smallest particle of a
substance that still has all the properties of that substance). DNA consists of two very long
sugar–phosphate strands, each linked together by certain chemical elements
called amines or bases arranged in a particular pattern. The amines are organic structures that
contain the genetic codes for building the proteins that make up organic life (hair coloring,
muscle, and skin, for example) and that control the life of each cell. Each section of DNA
containing a certain sequence (ordering) of these amines is called a gene. These genes are
located on rod-shaped structures called chromosomes, which are found in the nucleus of a cell.
DNA (deoxyribonucleic acid)
special molecule that contains the genetic material of the organism.
section of DNA having the same arrangement of chemical elements.
tightly wound strand of genetic material or DNA.
In this model of a DNA molecule, the two strands making up the sides of the “twisted ladder” are
composed of sugars and phosphates. The “rungs” of the ladder that link the two strands are
amines. Amines contain the genetic codes for building the proteins that make up organic life.
Humans have a total of 46 chromosomes in each cell of their bodies (with the exception of the
egg and the sperm). Twenty-three of these chromosomes come from the mother’s egg and the
other 23 from the father’s sperm. Most characteristics are determined by 22 such pairs, called
the autosomes. The last (23 ) pair determines the sex of the person. The two chromosomes of this
pair are called the sex chromosomes. Two X-shaped chromosomes indicate a female, while an X
and a Y indicate a male.
The 46 chromosomes can be arranged in pairs, with one member of each pair coming from the
mother and the other member from the father. Let’s consider just one of these pairs for the
In this particular pair of chromosomes, assume that there is a gene influencing hair color on each
chromosome. The observable color of the person’s hair will be determined by those two genes,
one gene from each parent. If both genes influence brown hair, the person will obviously have
brown hair, right? And if both influence blond hair, the person’s hair will be blond.
But what if one gene influences brown hair and the other blond hair?
The answer lies in the nature of each gene. Some genes that are more active in influencing a trait
are called dominant. A dominant gene will always be expressed in the observable trait, in this
case, hair color. For example, if Saida has a dominant gene for brown eyes, she will actually
have brown eyes—even with only one brown-eye gene.
referring to a gene that actively controls the expression of a trait.
Some genes are less active in influencing the trait and will only be expressed in the observable
trait if they are paired with another less active gene. These genes tend to recede, or fade, into the
background when paired with a more dominant gene, so they are called recessive. Blond is the
most recessive hair color and it will only show up as a trait if that person receives a blond-haircolor gene from each parent.
referring to a gene that only influences the expression of a trait when paired with an
identical gene.
What about red hair? And how come some people have a mixed hair color, like strawberry blond?
In reality, the patterns of genetic transmission of traits are usually more complicated. Almost all
traits are influenced by more than one pair of genes in a process called polygenic inheritance.
(Polygenic means “many genes.”) Sometimes certain kinds of genes tend to group themselves
with certain other genes, like the genes influencing blond hair and blue eyes. Other genes are so
equally dominant or equally recessive that they combine their traits in the organism. For
example, genes involved in blond hair and red hair are recessive. When a child inherits one of
each from his or her parents, instead of one or the other influencing the child’s hair color, the
genes may blend together to form a strawberry-blond mix.
Genetic and Chromosome Problems
Some disorders, such as Huntington’s disease (a breakdown in the neurons of the brain) and
Marfan’s syndrome (a connective tissue disorder), are carried by dominant genes. In these
disorders, only one parent needs to have the gene for the disorder to be passed on to offspring.
Other genetically determined disorders are carried by recessive genes. Diseases carried by
recessive genes are inherited when a child inherits two recessive genes, one from each parent.
Examples of disorders inherited in this manner are cystic fibrosis (a disease of the respiratory
and digestive tracts), sickle-cell anemia (a blood disorder), Tay-Sachs disorder (a fatal
neurological disorder), and phenylketonuria (PKU), in which an infant is born without the ability
to break down phenylalanine, an amino acid controlling coloring of the skin and hair. If levels of
phenylalanine build up, brain damage can occur; if untreated, it can result in severe intellectual
disabilities. Figure 8.1 illustrates a typical pattern of inheritance for dominant and recessive
genes using the example of PKU.
Figure 8.
This figure shows the variation of one or two parents carrying recessive genes and the result of
this in their offspring. (a) If only one parent carries the PKU gene, their children might be
carriers but will not have PKU. (b) Only if both parents are carriers of PKU, will a child have the
1-in-4 possibility of having PKU.
Figure 8.1 Full Alternative Text
Sometimes the chromosome itself is the problem. Although each egg and each sperm is only
supposed to have 23 chromosomes, in the formation of these cells a chromosome can end up in
the wrong cell, leaving one cell with only 22 and the other with 24. If either of these cells
survives to “mate,” the missing or extra chromosome can cause mild to severe problems in
development (American Academy of Pediatrics, 1995; Barnes & Carey, 2002; Centers for
Disease Control and Prevention, 2018a; Gardner & Sutherland, 1996; Sing et al., 2018).
One example of a chromosome disorder is Down syndrome, a disorder in which there is an extra
chromosome in what would normally be the 21st pair. Symptoms commonly include the physical
characteristics of almond-shaped, wide-set eyes, intellectual disability, and the increased risk of
organ failure later in life (Barnes & Carey, 2002; Hernandez & Fisher, 1996; Patel et al.,
2015). Other chromosome disorders occur when there is an extra sex chromosome in the 23rd
pair, such as Klinefelter syndrome, in which the 23rd set of sex chromosomes is XXY, with the
extra X producing a male with reduced masculine characteristics, enlarged breasts, obesity, and
excessive height (Bock, 1993; Frühmesser & Kotzot, 2011; Spaziani et al., 2018); and Turner
syndrome, in which the 23rd pair is actually missing an X, so that the result is a lone X
chromosome (Ranke & Saenger, 2001). These females tend to be very short, infertile, and
sexually underdeveloped (American Academy of Pediatrics, 1995; Conway, 2018; Cramer et
al., 2014; Hong et al., 2009; Rovet, 1993).
Down syndrome is a form of intellectual disability caused by an extra chromosome 21.
Kateryna Kon/Shutterstock
Concept Map L.O. 8.1, 8.2, 8.3
Figure L.O. 8.1, 8.2, 8.3 Full Alternative Text
Practice Quiz How much do you remember?
Pick the best answer.
1. In a
design, one group of people is followed and assessed at different times as
the group ages.
a. longitudinal
b. cross-sectional
c. cross-sequential
d. cross-longitudinal
The cognitive and social changes students go through because they are born and grow up
in an age of smartphones would be referred to as a(n)
a. experimental group.
b. dominance effect.
c. control group.
d. cohort effect.
Brandy has naturally blond hair. Based on this information, what do we know about
Brandy’s parents?
a. At least one of her parents has a recessive blond hair gene.
b. Each of her parents must have one recessive blond hair gene.
c. Each of her parents must have one dominant brown hair gene.
d. Neither of her parents has a recessive blond hair gene.
When sets of genes group together, the result can be multiple traits expressed as a single
dominant trait. This is best explained by the process known as
a. polygenic inheritance.
b. dominant inheritance.
c. recessive inheritance.
d. amines.
Which of the following is a disorder resulting from recessive inheritance?
a. Klinefelter syndrome
b. Down syndrome
c. Turner syndrome
d. cystic fibrosis
Which disorder is characterized by having only one X chromosome in the 23rd pairing?
a. Klinefelter syndrome
b. PKU
c. Turner syndrome
d. Tay-Sachs
8.4–8.5 Prenatal Development
From conception to the actual birth of the baby is a period of approximately 9 months,
during which a single cell becomes a complete infant. It is also during this time that
many things can have a positive or negative influence on the developing infant.
8.4 Fertilization
1. 8.4 Explain the process of fertilization, including the twinning process.
When an egg (also called an ovum) and a sperm unite in the process of fertilization, the
resulting single cell will have a total of 46 chromosomes and is called a zygote. Normally, the
zygote will begin to divide, first into two cells, then four, then eight, and so on, with each new
cell also having 46 chromosomes, because the DNA molecules produce duplicates, or copies, of
themselves before each division. (This division process is called mitosis.) Eventually, the mass of
cells becomes a baby. See Figure 8.2 for a closer look at what occurs once an egg is fertilized.
the union of the ovum and sperm.
the male sex cell.
the female sex cell, or egg.
cell resulting from the uniting of the ovum and sperm.
Figure 8.2
Journey of a Fertilized Egg
Sometimes this division process doesn’t work exactly this way, and twins or multiples are the
There are actually two kinds of twins (see Figure 8.3). Twins who are commonly referred to as
“identical” are monozygotic twins, meaning that the two babies come from one (mono)
fertilized egg (zygote). Early in the division process, the mass of cells splits completely—no one
knows exactly why—into two separate masses, each of which will develop into a separate infant.
The infants will be the same sex and have identical features because they each possess the same
set of 46 chromosomes. The other type of twin is more an accident of timing and is more
common in women who are older and who are from certain ethnic groups (Allen & Parisi,
1990; Bonnelykke, 1990; Fuchs & D’Alton, 2018; Imaizumi, 1998). A woman’s body may
either release more than one egg at a time or release an egg in a later ovulation period after a
woman has already conceived once. If two eggs are fertilized, the woman may give birth to
fraternal or dizygotic twins (two zygotes) or possibly triplets or some other multiple number of
babies (Bryan & Hallett, 2001; Fuchs & D’Alton, 2018). This is also more likely to happen to
women who are taking fertility drugs to help them get pregnant.
dizygotic twins
often called fraternal twins, occurring when two individual eggs get fertilized by separate
sperm, resulting in two zygotes in the uterus at the same time.
monozygotic twins
identical twins formed when one zygote splits into two separate masses of cells, each of
which develops into a separate embryo.
Figure 8.3
Monozygotic and Dizygotic Twins
Because identical twins come from one fertilized egg (zygote), they are called monozygotic.
Fraternal twins, who come from two different fertilized eggs, are called dizygotic.
Figure 8.3 Full Alternative Text
Pregnancies involving multiple babies are often very high risk and can be associated with
premature birth and low birth weight, both factors in possible long-term disabilities in both
physical and cognitive areas. Some of the babies may not survive, or doctors might actually
recommend selective termination of some of the babies to increase the chances of survival for
the remaining infants (Drugan & Weissman, 2017; Qin et al., 2015; Wilkinson et al., 2015).
This is a concern of an area called bioethics, the study of ethical and moral issues brought about
by new advances in biology and medicine and how those advances should influence policies and
practices (Kirsten, 2017; Muzur, 2014; Qin et al., 2015).
the study of ethical and moral issues brought about by new advances in biology and
For developmental psychologists, twins provide an important way to look at the contribution of
nature and nurture to human development. Researchers may seek out genetically identical twins
who have been separated at birth, looking at all the ways those twins are alike in spite of being
raised in different environments. It should be noted that the environments in which children are
raised within a particular culture are not necessarily that different, so twin studies are not a
perfect method. Researchers may also compare children who are adopted to their adoptive
parents (an environmental influence) and to their biological parents (a genetic influence).
See Learning Objective 13.12.
Thinking Critically 8.1
1. The time is coming when choosing the genetic traits of your child is going to be possible.
What kinds of ethical and practical problems may arise from this development?
8.5 Three Stages of Development
1. 8.5 Describe the three stages of prenatal development.
As you might imagine, the 9 months of a typical pregnancy involve a great many changes. While
many people think in terms of trimesters (3-month periods), there are really three stages of
pregnancy during which major aspects of development occur: the germinal period, the
embryonic period, and the fetal period (see Figure 8.4).
Figure 8.4
Three Periods of Pregnancy
The three periods of pregnancy are the germinal period, lasting about 2 weeks, the embryonic
period, from about 2 to 8 weeks, and the fetal period, which lasts from 8 weeks until the end of
Sources: (left) VEM/BSIP SA/Alamy Stock Photo; (center) Sebastian Kaulitzki/Science Photo Library/Alamy Stock Photo; (right)
Sebastian Kaulitzki/Science Photo Library/Getty Images.
Figure 8.4 Full Alternative Text
The Germinal Period
Once fertilization has taken place, the zygote begins dividing and moving down to the uterus, the
muscular organ that will contain and protect the developing organism. This process takes about a
week, followed by about a week during which the mass of cells, now forming a hollow ball,
firmly attaches itself to the wall of the uterus. This 2-week period is called the germinal
period of pregnancy. The placenta also begins to form during this period. The placenta is a
specialized organ that provides nourishment and filters away the developing baby’s waste
products. The umbilical cord also begins to develop at this time, connecting the organism to the
germinal period
first 2 weeks after fertilization, during which the zygote moves down to the uterus and
begins to implant in the lining.
How does a mass of cells become a baby, with eyes, nose, hands, feet, and so on? How do all those different
things come from the same original single cell?
During the germinal period, the cells begin to differentiate, or develop into specialized cells, in
preparation for becoming all the various kinds of cells that make up the human body—skin cells,
heart cells, and so on. Perhaps the most important of these cells are the stem cells, which stay in a
somewhat immature state until needed to produce more cells. Researchers are looking into ways
to use stem cells found in the umbilical cord to grow new organs and tissues for transplant or to
repair neurological damage (Canals et al., 2018; Chen & Ende, 2000; Ding et al.,
2015; Holden & Vogel, 2002; Li et al., 2018; Lu & Ende, 1997). See Learning
Objective 2.11.
The Embryonic Period
Once firmly attached to the uterus, the developing organism is called an embryo.
The embryonic period will last from 2 weeks after conception to 8 weeks, and during this time
the cells will continue to specialize and become the various organs and structures of a human
infant. By the end of this period, the embryo is about 1 inch long and has primitive eyes, nose,
lips, teeth, and little arms and legs, as well as a beating heart. Although no organ is fully
developed or completely functional at this time, nearly all are “there.”
name for the developing organism from 2 weeks to 8 weeks after fertilization.
embryonic period
the period from 2 to 8 weeks after fertilization, during which the major organs and
structures of the organism develop.
Critical Periods
As soon as the embryo begins to receive nourishment from the mother through the placenta, it
becomes vulnerable to hazards such as diseases of the mother, drugs, and other toxins that can
pass from the mother through the placenta to the developing infant. Because of this direct
connection between mother and embryo and the fact that all major organs are in the process of
forming, we can clearly see the effects of critical periods, times during which some
environmental influences can have an impact—often devastating—on the development of the
infant. The structural development of the arms and legs, for example, is only affected during the
time that these limbs are developing (3 to 8 weeks), whereas the heart’s structure is most affected
very early in this period (2 to 6 weeks). Other physical and structural problems can occur with
the central nervous system (2 to 5 weeks), eyes (3 to 8 weeks), and the teeth and roof of the
mouth (about 7 to 12 weeks).
critical periods
times during which certain environmental influences can have an impact on the
development of the infant.
Prenatal Hazards: Teratogens
Any substance such as a drug, chemical, virus, or other factor that can cause a birth defect is
called a teratogen. Table 8.2 shows some common teratogens and their possible negative effects
on the developing embryo.
any factor that can cause a birth defect.
Table 8.2
Common Teratogens
Teratogenic Agent
Effect on Development
Measles, Mumps, and Rubella
Blindness, deafness, heart defects, brain damage
Irritability, nervousness, tremors; infant is easily disturbed, startled
Decreased height, low birth weight, respiratory problems, seizures, learning diff
Fetal alcohol spectrum disorders (FASDs), e.g., fetal alcohol syndrome (intellec
Miscarriage, low birth weight, stillbirth, short stature, intellectual disability, learni
Intellectual disability, blindness
Vitamin A (high doses)
Facial, ear, central nervous system, and heart defects
Miscarriage, low birth weight
Brain swelling, spinal abnormalities, deafness, blindness, intellectual disability
High Water Temperatures
Increased chance of neural tube defects
Source: Based on March of Dimes Foundation (2006); Organization of Teratology Information Specialists (2017); Shepard & Lemire
One of the more common teratogens is alcohol. Consumption of alcohol during pregnancy,
particularly during the critical embryonic period, can lead to one of several possible fetal alcohol
spectrum disorders (FASDs), in which a combination of physical, mental, and behavioral
problems may be present. For example, the most severe FASD, fetal alcohol syndrome (FAS),
includes a series of physical and mental defects including stunted growth, facial deformities, and
brain damage (Andreu-Fernandez et al., 2019; Denny et al., 2017; Rangmar et al., 2015).
Exposure to alcohol in early pregnancy is the leading known cause of intellectual disability
(previously called mental retardation) in the Western hemisphere (Abel & Sokol, 1987; Caley et
al., 2005). Globally, 8 out of every 1,000 children born have some degree of FASD, and one out
of every 13 women who drank alcohol while pregnant has given birth to a child with a FASD
(Lange et al., 2017). FASDs are extremely preventable, and no amount of alcohol is safe to
drink while pregnant.
fetal alcohol spectrum disorder (FASD)
a group of possible conditions caused by a mother consuming alcohol during pregnancy,
in which a combination of physical, mental, and behavioral problems may be present
The Fetal Period: Grow, Baby, Grow
The fetal period is a period of tremendous growth lasting from about 8 weeks after conception
until birth. The length of the developing organism (now referred to as a fetus) increases by about
20 times, and its weight increases from about 1 ounce at 2 months to an average of a little over 7
pounds at birth. The organs, while accomplishing most of their differentiation in the embryonic
period, continue to develop and become functional. At this time, teratogens will more likely
affect the physical functioning (physiology) of the organs rather than their structure. The
functioning of the central nervous system, for example, is vulnerable throughout the fetal period,
as are the eyes and the external sexual organs.
fetal period
the time from about 8 weeks after conception until the birth of the baby.
name for the developing organism from 8 weeks after fertilization to the birth of the
The last few months continue the development of fat and the growth of the body, until about the
end of the 38th week. At 38 weeks, the fetus is considered full term. Most babies are born
between 38 and 40 weeks. Babies born before 38 weeks are called preterm or premature and may
need life support to survive. If they are very premature, they may also experience problems later
in life. This is especially true if the baby weighs less than 5½ pounds at birth. How early can an
infant be born and still survive? The age of viability (the point at which it is possible for an
infant to survive outside the womb) is between 22 and 26 weeks, with the odds of survival
increasing from 10 percent at 22 weeks up to about 85 percent at 26 weeks (National
Commission for the Protection of Human Subjects of Biomedical and Behavioral Research,
2006). Those odds will also increase if the infant is in a facility with advanced neonatal health
care (Rysavy et al., 2015).
This pregnant woman is getting an ultrasound. Ultrasounds use high-frequency sound waves to
create a picture, or sonogram, that allows doctors to see any physical deformities and make
accurate measurements of gestational age without risk to the mother or the fetus.
The most likely time for a miscarriage, or spontaneous abortion, is in the first 3 months, as the
organs are forming and first becoming functional (Katz, 2007; Speroff et al., 1999). Some 15 to
20 percent of all pregnancies end in miscarriage, many so early that the mother may not have
even known she was pregnant (American College of Obstetricians and Gynecologists,
2015; Doubilet et al., 2013; Hill, 1998; Medical Economics Staff, 1994; Nelson et al., 2015).
When a miscarriage occurs, it is most likely caused by a genetic defect in the way the embryo or
fetus is developing that will not allow the infant to survive. In other words, there isn’t anything
that the mother did wrong or that could have been done to prevent the miscarriage.
Concept Map L.O. 8.4,8.5
Figure L.O. 8.4, 8.5 Full Alternative Text
Practice Quiz How much do you remember
Pick the best answer.
1. The first 2 weeks of pregnancy are called the
a. germinal
b. placental
c. embryonic
d. fetal
2. Which of the following does NOT happen in the germinal period?
a. A dividing mass of cells travels to the uterus.
b. Developing organs can be affected by toxins passing through the placenta.
c. A mass of cells form a hollow ball.
d. Cells begin to differentiate.
3. The period of pregnancy that contains the clearest examples of critical periods is
a. germinal
b. embryonic
c. fetal
d. gestational
4. Intellectual disability and blindness are possible outcomes of the effects of
the developing baby.
a. mercury
b. caffeine
c. alcohol
d. cocaine
8.6–8.8 Infancy and Childhood
Infancy and early childhood are a time of rapid growth and development in the body, motor
skills, cognitive abilities, and sensory systems.
8.6 Physical Development
1. 8.6 Describe the physical and sensory changes that take place in infancy and childhood.
Immediately after birth, several things start to happen. The respiratory system begins to function,
filling the lungs with air and putting oxygen into the blood. The blood now circulates only within
the infant’s system because the umbilical cord has been cut. Body temperature is now regulated
by the infant’s own activity and body fat (which acts as insulation) rather than by the amniotic
fluid. The digestive system probably takes the longest to adjust to life outside the womb. This is
another reason for the baby’s excess body fat. It provides fuel until the infant is able to take in
enough nourishment on its own. That is why most babies lose a little weight in the first week
after birth.
How much can babies really do? Aren’t they pretty much unaware of what’s going on around them at first?
Surprisingly, babies can do quite a lot more than you might think. Researchers have developed
ways of studying what infants cannot tell us in words. Two common methods are the use
of preferential looking and habituation. Preferential looking assumes that the longer an infant
spends looking at a stimulus, the more the infant prefers that stimulus over others (Fantz, 1961).
Habituation is the tendency for infants (and adults) to stop paying attention to a stimulus that
does not change. See Learning Objective 3.3. By exposing the infant to an unchanging sound or
picture, for example, researchers can wait for the infant to habituate (look away) and then change
the stimulus. If the infant reacts (dishabituates), the infant is capable of detecting that change
(Columbo & Mitchell, 2009).
Babies come into this world able to interact with it. Infants have a set of innate (existing from
birth), involuntary behavior patterns called reflexes. Until a baby is capable of learning more
complex means of interaction, reflexes help the infant survive. Figure 8.5 shows five infant
reflexes. Pediatricians use these and other reflexes to determine whether a newborn’s nervous
system is working properly.
Figure 8.5
Five Infant Reflexes
Shown here are (a) grasping reflex; (b) startle reflex (also known as the Moro reflex); (c) rooting
reflex (when you touch a baby’s cheek, it will turn toward your hand, open its mouth, and search
for the nipple); (d) stepping reflex; and (e) sucking reflex. These infant reflexes can be used to
check the health of an infant’s nervous system. If a reflex is absent or abnormal, it may indicate
brain damage or some other neurological problem.
Sources: (a) Tony Wear/Shutterstock; (b) Jules Selmes/Pearson Education Ltd; (c) Cathy Melloan/PhotoEdit; (d) Denise
Hager/Catchlight Visual Services/Alamy Stock Photo; (e) Vlavetal/Shutterstock.
Figure 8.5 Full Alternative Text
Motor Development: From Crawling to a Blur of Motion
Infants manage a tremendous amount of development in motor skills from birth to about 2 years
of age. Figure 8.6 shows some of the major physical milestones of infancy. When looking at the
age ranges listed, remember that even these ranges are averages based on large samples of
infants. An infant may reach these milestones earlier or later than the average and still be
considered to be developing normally.
Figure 8.6
Six Motor Milestones
Shown here are (a) raising head and chest—2 to 4 months, (b) rolling over—2 to 5 months, (c)
sitting up with support—4 to 6 months, (d) sitting up without support—6 to 7 months, (e)
crawling—7 to 8 months, and (f) walking—8 to 18 months. The motor milestones develop as the
infant gains greater voluntary control over the muscles in its body, typically from the top of the
body downward. This pattern is seen in the early control of the neck muscles and the much later
development of control of the legs and feet.
Sources: (a) Michael Pettigrew/Shutterstock; (b) Keisuke kai/123RF; (c) Tatiana Chekryzhova/123RF; (d) Samuel Borges
Photography/Shutterstock; (e) Oksana Kuzmina/123RF; (f) Ivanko80/Shutterstock.
Figure 8.6 Full Alternative Text
Brain Development
At birth, an infant’s brain consists of more than 100 billion neurons. Rapid and extensive growth
of these neurons occurs as the brain triples in weight from birth to age 3 years, with much of the
increase caused by growth of new dendrites, axon terminals, and increasing numbers of synaptic
connections (Nelson, 2011; Paredes et al., 2016). Surprisingly, the development of the infant
brain after birth involves a necessary loss of neurons called synaptic pruning, as unused synaptic
connections and nerve cells are cleared away to make way for functioning connections and cells
(Couperus & Nelson, 2006; Graven & Browne, 2008; Kozberg et al., 2013; Zhan et al.,
2014). This process is similar to weeding your garden—you take out the weeds to make room for
the plants that you want.
Baby, Can You See Me? Baby, Can You Hear Me? Sensory
I’ve heard that babies can’t see or hear very much at birth. Is that true?
Although most infant sensory abilities are fairly well developed at birth, some require a bit more
time to reach “full power.” The sense of touch is the most well developed, understandable when
you realize how much skin-to-womb contact the baby has in the last months of pregnancy. The
sense of smell is also highly developed. Breast-fed babies can actually tell the difference
between their own mother’s milk scent and another woman’s milk scent within a few days after
Taste is also nearly fully developed. At birth, infants show a preference for sweets (and human
breast milk is very sweet) and by 4 months have developed a preference for salty tastes (which
may come from exposure to the salty taste of their mother’s skin). Sour and bitter, two other taste
sensations, produce spitting up and the making of horrible faces (Ganchrow et al., 1983).
Hearing is functional before birth but may take a little while to reach its full potential after the
baby is born. The fluids of the womb first must clear out of the auditory canals completely. From
birth, newborns seem most responsive to high pitches, as in a woman’s voice, and low pitches, as
in a man’s voice.
The least functional sense at birth is vision. The eye is quite a complex organ. See Learning
Objective 3.4. The rods, which see in black and white and have little visual acuity, are fairly
well developed at birth, but the cones, which see color and provide sharpness of vision, will take
about another 6 months to fully develop. As a result, the newborn has relatively poor color
perception when compared to sharply contrasting lights and darks until about 2 months of age
(Adams, 1987) and has fairly “fuzzy” vision, much as a nearsighted person would have. The lens
of the newborn stays fixed until the muscles that hold it in place mature. Until then the newborn
is unable to shift what little focus it has from close to far. Thus, newborns actually have a fixed
distance for clear vision of about 7–10 inches, which is the distance from the baby’s face to the
mother’s face while nursing (Slater, 2000; von Hofsten et al., 2014).
Newborns also have visual preferences at birth, as discovered by researchers using preferential
looking, measures of the time that infants spent looking at certain visual stimuli (Fantz, 1961).
They found that infants prefer to look at complex patterns rather than simple ones, three
dimensions rather than two, and that the most preferred visual stimulus was a human face. The
fact that infants prefer human voices and human faces (DeCasper & Fifer, 1980; DeCasper &
Spence, 1986; Fantz, 1964; Maurer & Young, 1983; Morii & Sakagami, 2015) makes it
easier for them to form relationships with their caregivers and to develop language later on.
Infants’ preference for seeing things in three dimensions suggests that they possess depth
perception. The following classic experiment provided evidence for that assumption.
Classic Studies in Psychology
The Visual Cliff
Eleanor Gibson and her fellow researcher, Michael Walk, wondered if infants could perceive the
world in three dimensions, and so they devised a way to test babies for depth perception (Gibson
& Walk, 1960). They built a special table (see Figure 8.7) that had a big drop on one side. The
surface of the table on both the top and the drop to the floor were covered in a patterned
tablecloth, so that the different size of the patterns would be a cue for depth (remember, in size
constancy, if something looks smaller, people assume it is farther away from them).
See Learning Objective 3.14. The whole table was then covered by a clear glass top, so that a
baby could safely be placed on or crawl across the “deep” side.
Figure 8.7
The Visual Cliff Experiment
In the visual cliff experiment, the table has both a shallow and a “deep” side, with glass covering
the entire table. When an infant looks down at the deep-appearing side, the squares in the design
on the floor look smaller than the ones on the shallow side, forming a visual cue for depth.
Notice that this little girl seems to be very reluctant to cross over the deep-appearing side of the
table, gesturing to be picked up instead.
Source:Mark Richard/PhotoEdit
The infants tested in this study ranged from 6 to 14 months in age. They were placed on the
middle of the table and then encouraged (usually by their mothers) to crawl over either the
shallow side or the deep side. Most babies—81 percent—refused to crawl over the deep side,
even though they could touch it with their hands and feel that it was solid. They were upset and
seemed fearful when encouraged to crawl across. Gibson and Walk interpreted this as a very
early sign of the concept of depth perception.
Questions for Further Discussion
1. Does the fact that 19 percent of the infants did crawl over the deep side of the visual cliff
necessarily mean that those infants could not perceive the depth?
2. What other factors might explain the willingness of the 19 percent to crawl over the deep
3. Are there any ethical concerns in this experiment?
4. Ducks aren’t bothered by the visual cliff at all—why might that be?
8.7 Cognitive Development
1. 8.7 Compare and contrast two theories of cognitive development, and define autism
spectrum disorder.
By the time the average infant has reached the age of 1 year, it has tripled its birth weight and
added about another foot to its height. The brain triples its weight in the first 2 years, reaching
about 75 percent of its adult weight. By age 5, the brain is at 90 percent of its adult weight. This
increase makes possible a tremendous amount of major advances in cognitive development,
including the development of thinking, problem solving, and memory.
cognitive development
the development of thinking, problem solving, and memory.
Piaget’s Theory: Four Stages of Cognitive Development
Early researcher Jean Piaget developed his theory of cognitive development from detailed
observations of infants and children, most especially his own three children. Piaget believed that
children form mental concepts or schemas (sometimes referred to as schemes) as they
experience new situations and events. For example, if Sandy points to a picture of an apple and
tells her child, “that’s an apple,” the child forms a schema for “apple” that looks something like
that picture. Piaget also believed that children first try to understand new things in terms of
schemas they already possess, a process called assimilation. The child might see an orange and
say “apple” because both objects are round. When corrected, the child might alter the schema for
apple to include “round” and “red.” The process of altering or adjusting old schemas to fit new
information and experiences is accommodation (Piaget, 1952, 1962, 1983). Watch the
video Assimilation and Accommodation in Children to learn more about these processes.
cognitive development
a mental concept or framework that guides organization and interpretation of information,
which forms and evolves through experiences with objects and events.
Assimilation and Accommodation in Chilren
Piaget also proposed that there are four distinct stages of cognitive development that occur from
infancy to adolescence, as shown in Table 8.3 (Piaget, 1952, 1962, 1983).
Table 8.3
Piaget’s Stages of Cognitive Development
Source: Based on Piaget, J. (1926). The language and thought of the child. New York: Harcourt Brace. Piaget, J. (1962). Play, dreams
and imitation in childhood. New York: W. W. Norton. Piaget, J. (1983). Piaget’s theory. In W. Kessen (Ed.), Handbook of child
psychology: Volume 1. Theoretical models of human development (pp. 103–128). New York: Wiley
Table 8.3 Full Alternative Text
The Sensorimotor Stage
The sensorimotor stage (birth to age 2) is the first of Piaget’s stages. In this stage, infants use
their senses and motor abilities to learn about the world around them. At first, infants only have
the involuntary reflexes present at birth to interact with objects and people. As their sensory and
motor development progresses, they begin to interact deliberately with objects by grasping,
pushing, tasting, and so on. Infants move from simple repetitive actions, such as grabbing their
toes, to complex patterns, such as trying to put a shape into a sorting box.
sensorimotor stage
Piaget’s first stage of cognitive development, in which the infant uses its senses and
motor abilities to interact with objects in the environment.
By the end of the sensorimotor stage, infants have fully developed a sense of object
permanence, the knowledge that an object exists even when it is not in sight. For example, the
game of “peek-a-boo” is important in teaching infants that Mommy’s smiling face is always
going to be behind her hands. This is a critical step in developing language (and eventually
abstract thought), as words themselves are symbols of things that may not be present. Symbolic
thought, which is the ability to represent objects in one’s thoughts with symbols such as words,
becomes possible by the end of this stage, with children at 2 years old capable of thinking in
simple symbols and planning out actions.
object permanence
the knowledge that an object exists even when it is not in sight.
Why is it so easy for children to believe in Santa Claus and the Tooth Fairy when they’re little?
The Preoperational Stage
The preoperational stage (ages 2–7) is a time of developing language and concepts. Children,
who can now move freely about in their world, no longer have to rely only on senses and motor
skills but now can ask questions and explore their surroundings more fully. Pretending and
make-believe play become possible because children at this stage can understand, through
symbolic thinking, that a line of wooden blocks can “stand in” for a train. They are limited,
however, in several ways. They are not yet capable of logical thought—they can use simple
mental concepts but are not able to use those concepts in a more rational, logical sense. They
believe that everything is alive and has feelings just like their own, a quality called animism, so
they might apologize to a chair for bumping it. They also tend to believe that what they see is
literally true, so when children of this age see Santa Claus in a book, on television, or at the mall,
Santa Claus becomes real to them. It doesn’t occur to them to think about how Santa might get to
every child’s house in one night or why those toys he delivers are the same ones they saw in the
store just last week.
preoperational stage
Piaget’s second stage of cognitive development, in which the preschool child learns to
use language as a means of exploring the world.
Another limitation is egocentrism, the inability to see the world through anyone else’s eyes but
one’s own. For the preoperational child, everyone else must see what the child sees, and what is
important to the child must be important to everyone else. For example, 2-year-old Hiba, after
climbing out of her crib for the third time, was told by her mother, “I don’t want to see you in
that living room again tonight!” Hiba’s next appearance was made with her hands over her
eyes—if she couldn’t see her mother, her mother couldn’t see her. Egocentrism is not the same
as being egotistical or selfish—it would also be egocentric, but completely unselfish, if 4-yearold Jamal wants to give his grandmother an action figure for her birthday because that’s
what he would want.
the inability to see the world through anyone else’s eyes.
Remember that children in this stage are also overwhelmed by appearances. A child who
complains that his piece of pie is smaller than his brother’s may be quite happy once his original
piece is cut into two pieces—now he thinks he has “more” than his brother. He has focused only
on the number of pieces, not the actual amount of the pie. Focusing only on one feature of some
object rather than taking all features into consideration is called centration. In the coin example
in Figure 8.8, children of this stage will focus (or center) on the length of the top line of coins
only and ignore the number of coins. Centration is one of the reasons that children in this stage
often fail to understand that changing the way something looks does not change its substance.
The ability to understand that altering the appearance of something does not change its amount
(as in the coin example), its volume, or its mass is called conservation.
in Piaget’s theory, the tendency of a young child to focus only on one feature of an object
while ignoring other relevant features.
in Piaget’s theory, the ability to understand that simply changing the appearance of an
object does not change the object’s nature.
Figure 8.8
Conservation Experiment
In this conservation task, pennies are laid out in two equal lines. When the pennies in the top line
are spaced out, the child who cannot yet conserve will centrate on the top line and assume that
there are actually more pennies in that line.
Figure 8.8 Full Alternative Text
Preoperational children fail at conservation not only because they centrate (focus on just one
feature, such as the number of pieces of pie) but also because they are unable to “mentally
reverse” actions. This feature of preoperational thinking is called irreversibility. For example, if
a preoperational child sees liquid poured from a short, wide glass into a tall, thin glass, the child
will assume that the second glass holds more liquid. This failure to “conserve” (save) the volume
of liquid as it takes on a different shape in the tall, thin glass is not only caused by the child’s
centration on the height of the liquid in the second glass but also by the inability of the child to
imagine pouring the liquid back into the first glass and having it be the same amount again.
Similar “reasoning” causes children of this age to assume that a ball of clay, when rolled out into
a “rope” of clay, is now greater in mass. Watch the video Conservation to see this in action.
in Piaget’s theory, the inability of the young child to mentally reverse an action.
Concrete Operations
In the concrete operations stage (ages 7–12), children finally become capable of conservation
and reversible thinking. Centration no longer occurs as children become capable of considering
all the relevant features of any given object. They begin to think more logically about beliefs
such as Santa Claus or the Tooth Fairy and to ask questions, eventually coming to their own
more rational conclusions about these fantasies of early childhood. They are in school, learning
all sorts of science and math, and are convinced that they know more than their parents at this
point (an impression that will likely not change until early adulthood, when their parents seem to
get smarter as they get older).
concrete operations stage
Piaget’s third stage of cognitive development, in which the school-age child becomes
capable of logical thought processes but is not yet capable of abstract thinking.
These concrete operational children, seen in a science class, have begun to think logically and
are able to solve many kinds of problems that were not possible for them to solve while in the
preoperational stage.
Jamie Grill/JGI/Getty Images
The major limitation of this stage is the inability to deal effectively with abstract concepts.
Abstract concepts are those that do not have some physical, concrete, touchable reality. For
example, “freedom” is an abstract concept. People can define it, they can get a good sense of
what it means, but there is no “thing” that they can point to and say, “This is freedom.” Concrete
concepts, which are the kind of concepts understood by children of this age, are about objects,
written rules, and real things. Children need to be able to see it, touch it, or at least “see” it in
their heads to be able to understand it.
Formal Operations
In the last of Piaget’s stages, formal operations (age 12 to adulthood), abstract thinking
becomes possible. Teenagers not only understand concepts that have no physical reality, but also
they get deeply involved in hypothetical thinking, or thinking about possibilities and even
impossibilities. “What if everyone just got along?” “If women were in charge of countries, would
there be fewer wars?” For an example of the kind of thinking that occurs in this stage, watch the
video Formal Operational Thought.
formal operations stage
Piaget’s last stage of cognitive development, in which the adolescent becomes capable of
abstract thinking.
Formal Operational Thought
Piaget did not believe that everyone would necessarily reach formal operations, and studies show
that only about half of all adults in the United States reach this stage (Sutherland, 1992). Adults
who do not achieve formal operations tend to use a more practical, down-to-earth kind of
intelligence that suits their particular lifestyle. Successful college students, however, need
formal-operational thinking to succeed in their college careers, as most college classes require
critical thinking, problem-solving abilities, and abstract thinking based on formal-operational
skills (Bolton & Hattie, 2017;Powers, 1984).
Others have proposed another stage beyond formal operations, a relativistic thinking stage found
in young adults, particularly those who have found their old ways of thinking in “black and
white” terms challenged by the diversity they encounter in the college environment (LaBouvieVief, 1980, 1992; Perry, 1970). In this kind of thinking, young adults recognize that all
problems cannot be solved with pure logic, and there can be multiple points of view for a single
Evaluating Piaget’s Theory
Piaget saw children as active explorers of their surroundings, engaged in the discovery of the
properties of objects and organisms within those surroundings. Educators have put Piaget’s ideas
into practice by allowing children to learn at their own pace, by “hands-on” experience with
objects, and by teaching concepts that are at the appropriate cognitive level for those children
(Brooks & Brooks, 1993). But Piaget’s theory has also been criticized on several points. Some
researchers believe that the idea of distinct stages of cognitive development is not completely
correct and that changes in thought are more continuous and gradual rather than abruptly
jumping from one stage to another (Courage & Howe, 2002; Feldman, 2003; Schwitzgebel,
1999; Siegler, 1996). Others point out that preschoolers are not as egocentric as Piaget seemed to
believe (Flavell, 1999) and that object permanence exists much earlier than Piaget thought
(Aguiar & Baillargeon, 2003; Baillargeon, 1986).
Vygotsky’s Theory: The Importance of Being There
Russian psychologist Lev Vygotsky’s pioneering work in developmental psychology has had a
profound influence on school education in Russia, and interest in his theories continues to grow
throughout the world (Bodrova & Leong, 1996; Duncan, 1995;Shabani, 2016). Vygotsky
wrote about children’s cognitive development but differed from Piaget in his emphasis on the
role of others in cognitive development (Vygotsky, 1934/1962, 1978, 1987). Whereas Piaget
stressed the importance of the child’s interaction with objects as a primary factor in cognitive
development, Vygotsky stressed the importance of social and cultural interactions with other
people, typically more highly skilled children and adults. Vygotsky believed that children
develop cognitively when someone else helps them by asking leading questions and providing
examples of concepts in a process called scaffolding. In scaffolding, the more highly skilled
person gives the learner more help at the beginning of the learning process and then begins to
withdraw help as the learner’s skills improve (Gonulal & Loewen, 2018; Rogoff, 1994).
process in which a more skilled learner gives help to a less skilled learner, reducing the
amount of help as the less skilled learner becomes more capable.
This girl is helping her younger brother learn to read a book. Vygotsky’s view of cognitive
development states that the help of skilled others aids in making cognitive advances such as this
Vygotsky also proposed that each developing child has a zone of proximal development (ZPD),
which is the difference between what a child can do alone versus what a child can do with the
help of a teacher. For example, if Jenny can do fourth-grade math problems by herself but also
can successfully work sixth-grade math problems with the help of a teacher, her ZPD is about 2
years: the difference between what she can do alone and what she can do with help. Suzi might
be the same age as Jenny and just as skilled at working fourth-grade math problems (and might
even score the same on a traditional IQ test), but if Suzi can only work up to fifth-grade math
problems with the teacher’s help, Suzi’s ZPD is only about 1 year and is not as great as Jenny’s.
Both girls are smart, but Jenny could be seen as possessing a higher potential intelligence than
Suzi. This might be a better way of thinking about intelligence: It isn’t what you know (as
measured by traditional tests), it’s what you can do.
zone of proximal development (ZPD)
Vygotsky’s concept of the difference between what a child can do alone and what that
child can do with the help of a teacher.
Other researchers have applied Vygotsky’s social focus on learning to the development of a
child’s memory for personal (autobiographical) events, finding evidence that children learn the
culturally determined structures and purposes of personal stories from the early conversations
they have with their parents. This process begins with the parent telling the story to the very
young child, followed by the child repeating elements of the story as the child’s verbal abilities
grow. The child reaches the final stage at around age 5 or 6 when the child creates the personal
story entirely—an excellent example of scaffolding (Fivush et al., 1996; Fivush & Nelson,
2004; Gonulal & Loewen, 2018; Nelson, 1993). Unlike Piaget, who saw a child’s talking to
himself or herself as egocentric, Vygotsky thought that private speech was a way for the child to
“think out loud” and advance cognitively. As adults, we still do this when we talk to ourselves to
help solve a particular problem. Vygotsky’s ideas have been put into practice in education
through the use of cooperative learning, in which children work together in groups to achieve a
common goal, and in reciprocal teaching, in which teachers lead students through the basic
strategies of reading until the students themselves become capable of teaching the strategies to
others. Chapter Seven details the stages of language development in infancy and childhood.
See Learning Objective 7.12.
Autism Spectrum Disorder
Before leaving the topic of cognitive development in infancy, let’s briefly discuss a topic that,
thanks to inaccurate and false viral posts on various social media forums, is very misunderstood:
the causes underlying autism spectrum disorder. Autism spectrum disorder (ASD) is a
neurodevelopmental disorder that actually encompasses a whole range of previous disorders
(with what may be an equally broad range of causes), which cause problems in thinking, feeling,
language, and social skills in relating to others (American Psychiatric Association,
2013; Atladóttir et al., 2009; Johnson & Myers, 2007; Lai et al., 2015; Schuwerk et al.,
Theory of mind is a term that refers to the ability to understand not only your own mental states,
such as beliefs, intentions, and desires, but also to understand that other people have beliefs,
intentions, and desires that may be different from yours (Baron-Cohen et al., 1985). Autism
research suggests that one of the main problems for people with autism is that they do not
possess a theory of mind, failing to understand that other people have their own points of view
(Baron-Cohen et al., 1985; Kimhi, 2014; Korkmaz, 2011).
Research continues into the possible causes of ASD, with studies implicating genetic mutations,
changes in certain areas of the brain, and even the possibility that a maternal grandmother’s
smoking during pregnancy could be related to her grandchild being at a higher risk for ASD (Cai
et al., 2018; Chen et al., 2018; Golding et al., 2017). Despite such scholarly research, rumors
and misinformation about a possible cause of autism have been circulating on the Internet for
many years (Mitchell & Locke, 2015). The major source of misinformation began in 1998,
when British gastroenterologist Dr. Andrew Wakefield published the results of two studies that
seemed to link the MMR (measles, mumps, and rubella) vaccine to autism and bowel disease in
children (Wakefield et al., 1998). Experts reviewed the quality of his research, and the studies
were quickly denounced as inadequate and dangerous by autism specialists and others
(Fitzpatrick, 2004; Judelsohn, 2007; Matthew & Dallery, 2007; Novella, 2007; Stratton et
al., 2001a, 2001b). See Learning Objectives 1.8 and 1.9. Nevertheless, Wakefield’s publication
was followed by measles epidemics due to parents refusing the MMR inoculation for their
children, as well as an anti-vaccination movement founded on nothing more than fear and lack of
education about vaccination safety and importance (MacDougall & Monnais, 2018). The myth
of a link persists, in spite of numerous studies that have consistently failed to show any link
between the MMR vaccine and autism (Burns, 2010; Gilberg & Coleman, 2000; Jain et al.,
2015; Johnson & Myers, 2007; Madsen et al., 2002; Mars et al., 1998; Taylor et al.,
1999; Thompson et al., 2007). In 2004, the other authors listed on the study formally retracted
the 1998 paper. In 2009, the final blow came to Wakefield’s credibility when it was discovered
that he had falsified his data, resulting in the revoking of his medical license in May of 2010
(Meikle & Bosley, 2010).
8.8 Psychosocial Development
1. 8.8 Identify the development of personality, relationships, and self-concept in infancy and
The psychological and social development of infants and children involves the development of
personality, relationships, and a sense of being male or female. Although these processes begin
in infancy, they will continue, in many respects, well into adulthood.
Why are some children negative and whiny while others are sweet and good natured?
One of the first ways in which infants demonstrate that they have different personalities (i.e., the
long-lasting characteristics that make each person different from others) is in
their temperament, the behavioral and emotional characteristics that are fairly well established
at birth. Researchers (Chess & Thomas, 1986; Thomas & Chess, 1977) have identified three
basic temperament styles of infants:
the behavioral characteristics that are fairly well established at birth, such as “easy,”
“difficult,” and “slow to warm up;” the enduring characteristics with which each person
is born.
1. Easy: “Easy” babies are regular in their schedules of waking, sleeping, and eating, and
are adaptable to change. Easy babies are happy babies and when distressed are easily
2. Difficult: “Difficult” babies are almost the opposite of easy ones. Difficult babies tend to
be irregular in their schedules and are very unhappy about change of any kind. They are
loud, active, and tend to be crabby rather than happy.
3. Slow to warm up: This kind of temperament is associated with infants who are less
grumpy, quieter, and more regular than difficult children but who are slow to adapt to
change. If change is introduced gradually, these babies will “warm up” to new people and
new situations.
Of course, not all babies will fall neatly into one of these three patterns—some children may be a
mix of two or even all three patterns of behavior, as Chess and Thomas (1986) discovered.
Even so, longitudinal research strongly suggests that these temperament styles last well into
adulthood and are strongly influenced by heredity (Kagan, 1998; Kagan et al., 2007; KopalSibley et al., 2018; Korn, 1984; Scarpa et al., 1995; Schwartz et al., 2010), although they are
somewhat influenced by the environment in which the infant is raised. For example, a “difficult”
infant who is raised by parents who are themselves very loud and active may not be perceived as
difficult by the parents, whereas a child who is slow to warm up might be perceived as difficult if
the parents themselves like lots of change and noise. The first infant is in a situation in which the
“goodness of fit” of the infant’s temperament to the parents’ temperament is very close, but the
parents of the second infant are a “poor fit” in temperament for that less active child (Chess &
Thomas, 1986). A poor fit can make it difficult to form an attachment, the important
psychosocial–emotional bond we will discuss next.
The emotional bond that forms between an infant and a primary caregiver is
called attachment. Attachment is an extremely important development in the social and
emotional life of the infant, usually forming within the first 6 months of the infant’s life
and showing up in a number of ways during the second 6 months, such as stranger
anxiety (wariness of strangers) and separation anxiety (fear of being separated from the
caregiver). Although attachment to the mother is usually the primary attachment, infants
can attach to fathers and to other caregivers as well.
the emotional bond between an infant and the primary caregiver.
Attachment Styles
Mary Ainsworth (Ainsworth, 1985; Ainsworth et al., 1978) devised a special experimental
design to measure the attachment of an infant to the caregiver; she called it the
“Strange Situation” (exposing an infant to a series of leave-takings and returns of the
mother and a stranger). Through this measurement technique, Ainsworth and another
colleague identified four attachment styles:
1. Secure: Infants labeled as secure were willing to get down from their mother’s
lap soon after entering the room with their mothers. They explored happily,
looking back at their mothers and returning to them every now and then (sort of
like “touching base”). When the stranger came in, these infants were wary but
calm as long as their mother was nearby. When the mother left, the infants got
upset. When the mother returned, the infants approached her, were easily
soothed, and were glad to have her back.
2. Avoidant: In contrast, avoidant babies, although somewhat willing to explore, did
not “touch base.” They did not look at the stranger or the mother and reacted
very little to her absence or her return, seeming to have no interest or concern.
3. Ambivalent: The word ambivalent means to have mixed feelings about
something. Ambivalent babies in Ainsworth’s study were clinging and unwilling to
explore, very upset by the stranger regardless of the mother’s presence,
protested mightily when the mother left, and were hard to soothe. When the
mother returned, these babies would demand to be picked up but at the same
time push the mother away or kick her in a mixed reaction to her return.
4. Disorganized–disoriented: In subsequent studies, other researchers (Main &
Hesse, 1990; Main & Solomon, 1990) found that some babies seemed unable to
decide just how they should react to the mother’s return. These disorganized–disoriented infants would approach her but with their eyes turned away from her,
as if afraid to make eye contact. In general, these infants seemed fearful and
showed a dazed and depressed look on their faces.
This toddler shows reluctance to explore her environment, instead clinging to her parent’s leg.
Such clinging behavior, if common, can be a sign of an ambivalent attachment.
It should come as no surprise that the mothers of each of the four types of infants also behaved
differently from one another. Mothers of secure infants were loving, warm, sensitive to their
infant’s needs, and responsive to the infant’s attempts at communication. Mothers of avoidant
babies were unresponsive, insensitive, and coldly rejecting. Mothers of ambivalent babies tried
to be responsive but were inconsistent and insensitive to the baby’s actions, often talking to the
infant about something totally unrelated to what the infant was doing at the time. Mothers of
disorganized–disoriented babies were found to be abusive or neglectful in interactions with the
Attachment is not necessarily the result of the behavior of the mother alone, however. The
temperament of the infant may play an important part in determining the reactions of the mother
(Goldsmith & Campos, 1982; Skolnick, 1986). For example, an infant with a difficult
temperament is hard to soothe. A mother with this kind of infant might come to avoid
unnecessary contact with the infant, as did the mothers of the avoidant babies in Ainsworth’s
Critics of Ainsworth’s Strange Situation research focus on the artificial nature of the design and
wonder if infants and mothers would behave differently in the more familiar surroundings of
home, even though Ainsworth’s experimental observers also observed the infants and mothers in
the home prior to the Strange Situation setting (Ainsworth, 1985). Other research has found
results supporting Ainsworth’s findings in home-based assessments of attachment (Blanchard &
Main, 1979). Other studies have also found support for the concept of attachment styles and
relative stability of attachment throughout the life span (Lutkenhaus et al., 1985; Main &
Cassidy, 1988; Owen et al., 1984; Umemura et al., 2018; Wartner et al., 1994;Widom et al.,
2018). Even adult relationships can be seen as influenced by the attachment style of the adult—
those who are avoidant tend to have numerous shallow and brief relationships with different
partners, whereas those who are ambivalent tend to have repeated breakups and makeups with
the same person (Bartholomew, 1990; Frederick et al., 2016; Harms et al., 2016; Hazan &
Shaver, 1987; Schroeder et al., 2014). Attachment style can also affect how people begin,
maintain, and end non-romantic relationships in their broader social network (Gillath et al.,
Influences On Attachment
As day care has become more widely acceptable and common, many parents have been
concerned about the effect of day care on attachment. Researchers have concluded that while
high-quality day care (i.e., consistent and educated caregivers, small child-to-caregiver ratio) is
important, the quality of parenting received by infants and toddlers in the home has a greater
impact on positive development (Belsky, 2005; Belsky & Johnson, 2005; Belsky et al., 2007).
Although there are some cultural differences in attachment—such as the finding that mothers in
the United States tend to wait for a child to express a need before trying to fulfill that need, while
Japanese mothers prefer to anticipate the child’s needs (Rothbaum et al., 2000), attachment
does not seem to suffer in spite of the differences in sensitivity. Evidence that similar attachment
styles are found in other cultures demonstrates the need to consider attachment as an important
first step in forming relationships with others, one that may set the stage for all relationships that
follow (Agerup et al., 2015; Hu & Meng, 1996; Keromoian & Leiderman, 1986; Nievar et
al., 2015; Posada et al., 2013; Stefanovic-Stanojevic et al., 2015; Zreik et al., 2017). Before
leaving the topic of attachment, let’s take a look at one of the first studies that examined the key
factors necessary for attachment.
Classic Studies in Psychology
Harlow and Contact Comfort
As psychologists began to study the development of attachment, they at first assumed that
attachment to the mother occurred because the mother was associated with satisfaction of
primary drives such as hunger and thirst. The mother is always present when the food (a primary
reinforcer) is presented, so the mother becomes a secondary reinforcer capable of producing
pleasurable feelings. See Learning Objective 5.5.
Psychologist Harry Harlow felt that attachment had to be influenced by more than just the
provision of food. He conducted a number of studies of attachment using infant rhesus monkeys
(Harlow, 1958). Noticing that the monkeys in his lab liked to cling to the soft cloth pad used to
line their cages, Harlow designed a study to examine the importance of what he termed contact
comfort, the seeming attachment of the monkeys to something soft to the touch.
He isolated eight baby rhesus monkeys shortly after their birth, placing each in a cage with two
surrogate (substitute) “mothers.” The surrogates were actually a block of wood covered in soft
padding and terry cloth and a wire form, both heated from within. For half of the monkeys, the
wire “mother” held the bottle from which they fed, while for the other half the soft “mother” held
the bottle. Harlow then recorded the time each monkey spent with each “mother.” If time spent
with the surrogate is taken as an indicator of attachment, then learning theory would predict that
the monkeys would spend more time with whichever surrogate was being used to feed them.
The results? Regardless of which surrogate was feeding them, all of the infant monkeys spent
significantly more time with the soft, cloth-covered surrogate. In fact, all monkeys spent very
little time with the wire surrogate, even if this was the one with the bottle. Harlow and his
colleagues concluded that “contact comfort was an important basic affectional or love variable”
(Harlow, 1958, p. 574).
The wire surrogate “mother” provides the food for this infant rhesus monkey. But the infant
spends all its time with the soft, cloth-covered surrogate. According to Harlow, this demonstrates
the importance of contact comfort in attachment.
Nina Leen/The LIFE Picture Collection/Getty Images
Harlow’s work represents one of the earliest investigations into the importance of touch in the
attachment process and remains an important study in human development.
Questions for Further Discussion
1. Even though the cloth surrogate was warm and soft and seemed to provide contact
comfort, do you think that the monkeys raised in this way would behave normally when
placed into contact with other monkeys? How might they react?
2. What might be the implications of Harlow’s work for human mothers who feed their
infants with bottles rather than breastfeeding?
Who Am I?: The Development of the Self-Concept
Infants begin life without understanding that they are separate from their surroundings and also
from the other people in their social world. The self-concept is the image you have of yourself,
and it is based on your interactions with the important people in your life. As infants experience
the world around them, they slowly learn to separate “me” from both physical surroundings and
the other people in their world.
the image of oneself that develops from interactions with important significant people in
one’s life.
One way to demonstrate a child’s growing awareness of self is known as the rouge test. A spot of
red rouge or lipstick is put on the end of the child’s nose and the child is then placed in front of a
mirror. Infants from about 6 months to a little over a year will reach out to touch the image of the
baby in the mirror, reacting as if to another child (Amsterdam, 1972; Courage & Howe, 2002).
In fact, some infants crawl or walk to the other side of the mirror to look for the “other.” But at
about 15 to 18 months of age, the infant begins to touch his or her own nose when seeing the
image in the mirror, indicating an awareness that the image in the mirror is the infant’s own
(Filippetti & Tsakiris, 2018; Nielsen et al., 2006). As the child grows, the self-concept grows to
include gender (“I’m a boy” or “I’m a girl”), physical appearances (“I have brown hair and blue
eyes”), and in middle childhood, personality traits and group memberships (Stipek et al., 1990).
I’ve heard that you shouldn’t pick up a baby every time it cries—that if you do, it might spoil the baby.
Erikson’s Theory
Unfortunately, a lot of people have not only heard this advice but also acted on it by frequently
ignoring an infant’s crying, which turns out to be a very bad thing for babies. When a baby under
6 months of age cries, it is an instinctive reaction meant to get the caregiver to tend to the baby’s
needs—hunger, thirst, pain, and even loneliness. Research has shown that babies whose cries are
tended to consistently (that is, the infant is fed when hungry, changed when wet, and so on) in
the early months are more securely attached at age 1 than those infants whose caregivers
frequently allow the infants to cry when there is a need for attention—hunger, pain, or wetness,
for example (Brazelton, 1992; Heinicke et al., 2000). Erik Erikson, a psychodynamic theorist
who emphasized the importance of social relationships in the development of personality, would
certainly disagree with letting a baby “cry it out,” although allowing an infant who has been fed,
changed, burped, and checked to cry on occasion will not damage attachment.
Erikson believed that development occurred in a series of eight stages, with the first four of these
stages occurring in infancy and childhood (Erikson, 1950; Erikson & Erikson, 1997).
See Learning Objective 13.2. Each of Erikson’s stages is an emotional crisis, or a kind of
turning point, in personality, and the crisis in each stage must be successfully met for normal,
healthy psychological development.
Erikson focused on the relationship of the infant and the child to significant others in the
immediate surroundings—parents and then later teachers and even peers. Table 8.4 summarizes
the conflict in each of Erikson’s eight stages and some of the implications for future
development (Erikson, 1950; Erikson & Erikson, 1997). For now, look at the first four stages
in particular.
Table 8.4
Erikson’s Psychosocial Stages of Development
Source: Based on Erikson, E. H. (1950). Childhood and society. New York: Norton.
Table 8.4 Full Alternative Text
Concept Map L.O. 8.6, 8.7, 8.8
Figure L.O. 8.6, 8.7, 8.8 Full Alternative Text
Practice Quiz How much do you remember?
Pick the best answer.
1. One way researchers study newborn development involves measuring how long infants
continue to focus upon a nonchanging stimulus. This technique is referred to as
a. adaptation.
b. habituation.
c. longitudinal study.
d. a cross-sectional design.
2. In which of Piaget’s stages would a child be who has just developed the ability to
a. sensorimotor
b. preoperational
c. concrete operations
d. formal operations
3. Vygotsky defines
as the process of helping less as the learner improves at a
given task.
a. scaffolding
b. habituation
c. zone of proximal development
d. metamemory
4. What kind of attachment, according to Ainsworth, is shown by a baby who clings to his
or her mother, gets upset when the mother leaves, and demands to be picked up but at the
same time kicks and pushes her away?
a. secure
b. avoidant
c. ambivalent
d. disorganized–disoriented
5. Studies by Harry Harlow showed that the most important element to developing
attachment is
a. feeding.
b. physical contact.
c. mental challenges.
d. sleep.
6. According to Erikson, which stage results in a sense of independence because of one’s
ability to control his or her own actions?
a. trust versus mistrust
b. autonomy versus shame and doubt
c. initiative versus guilt
d. generativity versus stagnation
The Facts About Immunizations
Addresses APA Learning Objectives 2.1: Use scientific reasoning to interpret psychological
phenomena; 2.3: Engage in innovative and integrative thinking and problem-solving.
You’d think that by now, people would be well aware that immunizations do not cause autism or
a host of other problems and that in fact immunization is a very good thing. Sadly, there is still a
big problem with people failing to vaccinate their children against deadly diseases because they
have been listening to the wrong people and reading the wrong information. In December of
2015, news outlets reported that an Australian elementary school (known for its tolerance of
parents who do not want to vaccinate their children) had suffered an outbreak of chicken pox
(Campbell, 2015). The school had only a 73 percent vaccination rate, compared to 92 percent in
the surrounding community. At least 80 of the 320 students (roughly 25 percent) were affected,
including some who had been vaccinated (they would get only mild cases of chicken pox,
however). Because so many unvaccinated children attend the school, this particular population
lost its “herd immunity”—the immunity a population gains over time as a significant majority of
its members become immune to a particular disease (Plotkin et al., 2011). Herd immunity is
being lost in many places around the globe: a polio outbreak in the Congo (Roberts, 2018),
smaller measles outbreaks in 21 U.S. states (Centers for Disease Control and Prevention,
2018c), and also a measles outbreak across Europe (The Associated Press, 2018) all took place
in 2018.
Why do parents fail to vaccinate? Primarily, it’s a failure of critical thinking. Think back to the
discussion of critical thinking in Chapter One of this text. See Learning Objective 1.5. The
first criterion of critical thinking was “there are very few ‘truths’ that do not need to be subjected
to testing.” The link between vaccines and autism, for example, has been well studied and tested
over many years, and the findings are clear: There is NO link (Burns, 2010; CDC,
2004, 2011, DeStefano et al., 2013; Gilberg & Coleman, 2000; Jain et al., 2015; Johnson &
Myers, 2007; Madsen et al., 2002; Mars et al., 1998; Offit & Bell, 1998; Stratton et al.,
2001a, 2001b; Taylor et al., 1999; Thompson et al., 2007; Institute of Medicine, 2012).
Unfortunately, the people involved in the antivaccination movement get their information not
from scientifically rigorous studies but from anecdotes and Internet blogs. The second criterion
of critical thinking was: All evidence is not equal in quality. Testimonials, anecdotes, and the
ravings of people on the Internet are not good evidence.
Another problem is the number of celebrities who have joined the antivaccination movement.
These people have no real expertise, but they do have the ability to reach a lot of people and—
unfortunately—some people are very willing to believe their favorite celebrity despite the lack of
any authority on the subject at hand. The third criterion is one that is often forgotten: Just
because someone is considered to be an authority or to have a lot of expertise does not make
everything that person claims automatically true, as the Wakefield disaster clearly demonstrated.
The evidence is what is important, and in the case of immunizations, the evidence is clear:
Vaccinate your children.
APA Goal 2
The Facts About Immunizations
Herd immunity is a term that refers to the immunity of a population to a particular disease,
typically because a majority of the population’s members have acquired immunity through
vaccination. As you can see from the diagram at the top, when a population does not have herd
immunity, a disease carried by only a few people, or even one person, can spread throughout the
whole population. This is what happened in the famous case of “Typhoid Mary,” in which a
woman who carried typhoid spread the disease to a large number of employees and their
families. As more of a population gets immunized (middle diagram), the spread of disease begins
to lessen. As most of the population gets immunized (bottom diagram), the spread of the disease
is minimized—the “herd” is immune.
Development Across the Life Span
Course Learning Outcomes for Unit VI
Upon completion of this unit, students should be able to:
5. Explain basic cognitive functions.
5.1 Relate theories of cognitive development to real-world scenarios.
5.2 Describe stages of cognitive development during childhood, adolescence, and adulthood.
5.3 Determine effective ways of dealing with developmental crises.
Learning Outcomes
Learning Activity
Unit Lesson
Chapter 8
Video: Formal Operational Thought
Unit VI Case Study
Unit Lesson
Chapter 8
Video: Formal Operations
Unit VI Case Study
Unit Lesson
Chapter 8
Video: Parenting Styles
Unit VI Case Study
Required Unit Resources
Chapter 8: Development Across the Life Span
View the following two videos that supplement the Chapter 8 reading. The page number is given as a
reference to the location of the video in the chapter.
Closed captioning is available by clicking the CC icon in the bottom right corner of the video screen.
Formal Operational Thought, p. 320
Parenting Styles, p. 338
Unit Lesson
Development Across the Life Span
Carrying and giving birth to multiple babies at once has risks, and some may consider the situation
overwhelming. Can you recall hearing about Nayda Suleman, also known as Octo-Mom? She became
famous back in 2009 when she gained notoriety after becoming pregnant via in vitro fertilization. She actually
gave birth to eight babies at once. What are your thoughts? Do you think having multiple births at once is
safe? If you were Nayda, would you have been concerned about the numerous risks related to developmental
complications? In your opinion, should she have been concerned about her babies’ cognitive development?
Within this unit, you will learn about the development of life from one’s conception until death. You will want to
pay close attention to the section on prenatal development. According to Ciccarelli and White (2020), there
are numerous factors that can negatively impact or harm one’s baby. Did you know that research has shown
PSY 1010, General Psychology
that smoking cigarettes can not only harm the mother, but it can present challenges
the fetus
as well?
UNIT xfor
However, do you think it is possible to stop pregnant moms from smoking? Can
you formulate some ideas
that would be helpful to improve this potential issue? Furthermore, another negative element that can directly
harm the fetus is the pregnant mother’s level of stress. Stop and ponder this critical fact for a moment. Can
you strategize creative ways in which you could help a pregnant mother eliminate, or at least decrease, her
level of stress? Ciccarreli and White (2020) stress the importance of avoiding certain dangers to prevent
numerous complications.
How does your baby relax? Does he or she enjoy reclining in a baby swing while
watching a cartoon and sipping on a warm bottle of the yummy white stuff? Do you
believe that certain forms of media like videos or music on the market can
remarkably increase a baby’s intelligence quotient (IQ) and brain development?
(Greenland, 2009)
Christakis (2009) purports that introducing a baby
to television at a very young age could possibly
stunt or delay the development of the baby,
particularly in relation to language progression.
Additional research has revealed that when
children are exposed to excessive amounts of
television as babies, they can have an increased
tendency to endure issues related to attention
deficits. One might consider this research when
determining the amount of time baby spends in
Too much screen
time could stunt
or delay the mental
of babies.
front of a screen.
Were you ever a working parent? Did you have to take your child to daycare while you earned a living? Were
you ever fearful that taking your child to daycare could negatively impact or diminish his or her de velopment?
Within this unit, you will learn about the different types of attachment. Can you recall the first time that you
took your baby to a sitter? Did you fear that the caregiver would form a stronger bond, or attachment, with
your baby during the day while you were working? Did you think your baby might experience separation
anxiety when you had to leave him or her? Pay close attention to the different attachment styles described by
Mary Ainsworth and colleagues to see if you agree with their findings.
Ciccarelli and White (2020) describe important research from one foundational scholar in this field. In fact,
Harry Harlow is well-known for his work with attachment theory. In essence, many psychologists during this
period argued that babies were attached to their mothers because they associated them with meeting their
basic needs of thirst and hunger. In essence, they believed that the mom represented a secondary
reinforcement that brought pleasant feelings. However, Harlow believed that attachment had more influences
than mere food. In fact, he sought to ascertain any issues related to contact comfort that might arise by
observing interactions between rhesus monkeys and props that were simulated to serve as their mothers.
One simulated mom was made from wire. The other mom was comprised of cloth and foam. Both of the fake
moms had bottles of milk attached. Harlow wanted to determine if the monkey would become attached to the
simulated mom simply because she had food. What do you think was the outcome? Do you think that
monkeys preferred one of the simulated mothers over the other? Do you think a baby values a soft touch,
regardless if the person is feeding him or her? How critically important is contact with a baby or small child for
that matter?
PSY 1010, General Psychology
Types of Development
Additional exploration of this chapter will reveal research that relates to
language and social development. In fact, Clark-Stewart (1991) suggested that
children can do well, if not better, outside of the home. She examined the
social and intellectual development of 150 children who were aged 2 to 4. It
was discovered that children who had attended daycare facilities had cognitive
development levels that were farther advanced when compared with children
who had remained at home with their mothers or personal babysitters. This
research provides encouraging details for parents who worry about their
children’s futures. Do not feel guilty if you are not a stay-at-home parent. Your
son or daughter could be more advantaged than you realize.
Think back to your adolescent years. Did you strive to please your parents?
On the other hand, did it mean more to you to fit in with your friends? What do
you think about teens today? Should we hold them fully responsible for their
behaviors or misbehaviors in certain situations?
Ciccarrelli and White (2020) further discuss moral, cognitive, and gender development in this chapter. As you
peruse the material, begin to examine any moral dilemmas that you faced as a teen. Who was included in
your support system? Was it difficult to make certain value-based decisions? You will learn about Lawrence
Kohlberg and his research in this area. Kohlberg believe that one’s ability to ascertain right from wrong was
akin to an evolutionary process over time that involves one’s ability to correctly embrace cognitive processing
skills. Let’s examine his reasoning. Think back to when you were young. Did you obey your parents because
you wanted to please them or primarily because you feared the punishment you would be forced to endure if
you did not obey? As you matured, did you slowly begin to value acceptance from your peers as well as
loyalty from them? What is your perspective now? As an adult, would you say that you are highly influenced
by morals that were instilled in you as a child or basic life principles that you have embraced as you have
matured? What are your thoughts in relation to Kohlberg’s views?
Should a teen be sent to prison if he or she commits murder? Research has been conducted that purports
that our brains are not fully mature until our early to mid-20s. In fact, some scholars posit that the frontal
lobes—the portions in our brains where reasoning primarily occurs—are quite often the one of the last
sections to fully mature. In fact, certain studies have argued that teenagers experience difficulties when trying
to control their impulses. So, based on this research, what do you think? Should a 16-year-old who commits a
horrendous crime be punished even though his or her brain is still developing?
Breast Milk or Formula?
Did you know that research exists that supports that babies should consume breast milk as opposed to
formula due to all of the benefits associated with the former? McCartney (2007) reviewed numerous studies,
which revealed a correlation between breastfeeding and higher IQ scores. Quite frankly, many studies have
shown that IQ scores that show differences as much as 6-7 points in children who received breast milk.
However, do not jump on the breast milk bandwagon too quickly. There is opposing research that questions
this correlation. In fact, these antagonists argue that numerous variables combine that impact a child’s level of
intelligence. The mother’s IQ, ethnicity, and socioeconomic stability must also be factored as well. What are
your thoughts? Do you think breast milk is the best milk for a baby?
PSY 1010, General Psychology
As you conclude your examination of this unit, take a moment to examine your own hopes and dreams. Do
you believe one’s beginning in life will directly impact his or her ending? Have you heard of a mid-life crisis?
Do you know someone who has experienced such? What physical changes in your body do you dread as you
get older? Consider the measures shown below that you could embrace to be proactive to prevent depression
or memory loss. Would you be willing to try those methods? Can you predict how you will feel as you face
your final stages in life and approach the death and dying process? Succinctly, do you think the ending of
your story can be better than the beginning was?
Christakis, D. A. (2009). The effects of infant media usage: What do we know and what should we learn? Acta
Pædiatrica, 98(1), 8–16.
Ciccarelli, S. K., & White, J. N. (2020). Psychology (6th ed.). Pearson.
Clarke-Stewart, K. A. (1991). A home is not a school: The effects of child care on children’s development. In
S. L. Hofferth & D. A. Phillips (Eds.), Child Care Policy Research. Journal of Social Issues, 47(2),
Greenland. (2009). Baby watching TV (ID 11157737) [Photograph]. Dreamstime.
McCartney, M. (2007). Mixed messages over breast milk and brainy babies. British Medical Journal,
335(7629), 1074.
Suggested Unit Resources
All videos that are referenced in Chapter 8 of the eTextbook are available in the following PowerPoint
Presentation. You are encouraged to view each short video for additional insight into this unit’s concepts.
Chapter 8 PowerPoint Presentation
PDF version of the Chapter 8 PowerPoint Presentation
Closed captioning is available for each video by clicking the CC icon in the bottom right corner of the video
PSY 1010, General Psychology
You are encouraged to read the following chapter in your eTextbook which covers
theories. This
information continues the conversation in this unit about cognitive development
by looking at personality—the
unique way each person thinks, acts, and feels.
Chapter 13: Theories of Personality
All videos that are referenced in Chapter 13 of the eTextbook are available in the following PowerPoint
Presentation. You are encouraged to view each short video for additional insight into this unit’s concepts.
Chapter 13 PowerPoint Presentation
PDF version of the Chapter 13 PowerPoint Presentation
Learning Activities (Nongraded)
Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit
them. If you have questions, contact your instructor for further guidance and information.
Test Yourself questions from Chapter 8 are located on p. 345 of your eTextbook. You can review these to
assess your understanding of the chapter material.
PSY 1010, General Psychology

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