Lifespan Development
Psychology 2012 –
Fall 2004
Introduction: Your Life Story
 Developmental Psychology – branch of psychology that
studies how people change mentally, physically, and
socially throughout the lifespan
– For every age and stage of life, developmental
psychologists investigate the influence of multiple
factors on development,
• including biological, environmental, social, cultural, and
behavioral factors
– Along with studying common patterns of growth and
change, developmental psychologists look at ways in
which people differ in their development
– Developmental psychologists often conceptualize the
lifespan in terms of basic stages of development
Introduction: Your Life Story
– Traditionally, the stages of the lifespan are defined by
age, which implies relatively sudden, age-related
changes as we move from one stage to the next
• Some aspects of development, such as prenatal development
and language development, are closely tied to critical periods
– Most of our physical, mental, and social changes,
however, occur gradually,
• And the theme of gradually unfolding changes throughout the
ages and stages of life will become more evident as we trace
the typical course of human development in this chapter
– Another important theme is the interaction between
heredity and environment,
• Traditionally called the nature-nurture issue
Genetic Contributions to Your
Life Story
 A chromosome is a long, threadlike structure
composed of twisted parallel strands of
deoxyribonucleic acid (DNA),
– which is the chemical basis of all heredity
 DNA contains the chemical genetic code that
directs the growth and development of many of
your unique characteristics
– Each gene is a unit of DNA instructions pertaining to
some characteristic,
• such as eye or hair color, or handedness
Genetic Contributions to Your
Life Story
 At conception, the genes carried on the 23
chromosomes contributed by your
biological mother’s ovum were paired with
– The genes carried on the 23 chromosomes
contributed by your biological father’s sperm
 Multiple gene pairs are involved in
directing many complex features of
Genetic Contributions to Your
Life Story
 Dominant and Recessive Characteristics
– Genotype – the underlying genetic makeup of a
particular individual
– Phenotype – the actual displayed traits
 When a genotype combines conflicting genetic
– the dominant gene will influence the trait actually
• Traits like freckles, dark eyes, dark hair, and dimples are
referred to as dominant characteristics
– Because they require only one member of a gene pair to be
dominant for the trait to be displayed
Genetic Contributions to Your
Life Story
 A recessive gene is a gene whose instructions are
not expressed if combined with a dominant gene
– Only expressed if paired with another recessive gene
• Recessive characteristics – traits whose expression requires
two identical recessive genes
– Like straight hair, attached earlobes, and flat feet
 We inherit from our biological parents a genetic
– the expression of which can be influenced by
environmental conditions
Genetic Contributions to Your
Life Story
 The sex chromosomes and sex-linked
recessive characteristics
– The sex chromosomes (the 23rd pair of
chromosomes) determine biological sex
• The large X chromosome carries more genes than
does the smaller Y chromosome, including genes
for traits unrelated to sex
– In females, the 23rd pair of chromosomes is made up of
two large X chromosomes
– In males, a large X chromosome and a smaller Y
chromosome make up the 23rd pair of chromosomes
Genetic Contributions to Your
Life Story
 The sex chromosomes and sex-linked recessive
– For males, the smaller Y chromosome often does not
contain a corresponding gene segment to match the
one on the X chromosome.
• This means that a male can display certain recessive
characteristics as the result of having only one recessive gene
carried on the X chromosome
– Like red-green color blindness and hemophilia
• Sex-linked recessive characteristics – traits determined by
recessive genes on the X chromosomes
Prenatal Development
 At conception, chromosomes from the
biological mother and father combine to form a
single cell – the fertilized egg (zygote)
 Prenatal stage – made up of three distinct
1. Germinal (first two weeks),
2. Embryonic (weeks 3-8), and
3. Fetal (week 9-birth) periods
Prenatal Development
 Germinal (zygotic) period – represents the
first two weeks of prenatal development
– The zygote undergoes rapid cell division
before becoming implanted on the mother’s
uterine wall
– By the end of the two-week germinal period,
the single-celled zygote has developed into a
cluster of cells called the embryo
The Zygote
First Division
Second Division
Prenatal Development
 The embryonic period – from weeks 3 to 8
– During this time of rapid growth and intensive cell
differentiation, the organs and major systems of the body form.
• Genes on the sex chromosomes and hormonal influences trigger the
initial development of the sex organs
– Protectively housed in the fluid-filled amniotic sac, the embryo’s
lifeline is the umbilical cord
• Via the umbilical cord, the embryo receives nutrients, oxygen, and
water and gets rid of carbon monoxide and other wastes
• The umbilical cord attaches the embryo to the placenta, a diskshaped tissue on the mother’s uterine wall
– The placenta prevents the mother’s blood from mingling with that of
the developing embryo,
• acting as a filter to prevent some, but not all, harmful substances
that might be present in the mother’s blood from reaching the
Prenatal Development
The embryonic period – from weeks 3 to 8
Teratogens – harmful agents or substances that can
cause malformations or defects in an embryo or a
Known teratogens include:
Exposure to radiation
Toxic industrial chemicals, such as mercury and PCBs
Diseases, such as rubella, syphilis, genital herpes, and AIDS
Drugs taken by the mother, such as alcohol, cocaine, and
The Embryo
1 month old Embryo
 Cocaine and Heroin: Miscarriage,
prematurity, birth defects
 Alcohol: Fetal alcohol syndrome, motor
development problems
 Smoking: Reduces oxygen flow, increases
CO2, increases odds of prematurity, low
birthweight, and miscarriage
Prenatal Development
 The third month is the beginning of the fetal
period, the final and longest stage of prenatal
– By the end of the third month, the fetus can move its arms, legs,
mouth, and head
During the fourth month, the mother experiences quickening –
she can feel the fetus moving
By the fifth month, the fetus has distinct sleep-wake cycles and
periods of activity
During the sixth month, the fetus’s brain activity becomes similar
to that of a newborn baby
During the final two months, the fetus will double in weight,
gaining an additional three to four pounds
Fetal Development
3 month old male
Development During Infancy
and Childhood
Initially, the newborn’s behavior is mostly limited to
reflexes that enhance his chances for survival.
Some major newborn reflexes:
1. The rooting reflex – the infant turns toward the source of the touch
and opens the mouth
2. The sucking reflex – just touching the newborn’s lips evokes this
3. The grasping reflex – the baby will grip your fingers so tightly that
he or she can be lifted upright
In addition, the newborn’s senses – vision, hearing,
smell, and touch – are keenly attuned to people,
helping the infant quickly learn to differentiate between the
mother and other humans
Development During Infancy
and Childhood
 Vision is the least developed sense at birth
– Optimal viewing distance for the newborn is
about 6-12 inches
• The perfect distance for a nursing baby to easily
focus on his mother’s face and make eye contact
 Newborns respond with increased alertness
to the sound of human voices
Development During Infancy
and Childhood
 Physical development
– At birth, the newborn’s brain is 25% of its adult
• Body weight is only 5% of its adult weight
– Newborns enter the world with an estimated 100
billion neurons
• After birth, the brain continues to develop rapidly
– The number of dendrites increases dramatically during the first
two years of life
– The axons of many neurons acquire myelin:
• the white, fatty covering that increases a neuron’s
communication speed
Development During Infancy
and Childhood
 Physical development
The basic sequence of motor skill
development during infancy is universal, but
average ages can be a little deceptive
Each infant has his or her own:
1. genetically programmed timetable of physical
maturation and
2. developmental readiness to master different motor
• Like rolling over, sitting up, and standing
Development During Infancy
and Childhood
 Social and personality development
– Forming close social and emotional relationships with
caregivers is essential to the infant’s physical and
psychological well-being
– Temperamental qualities: Babies are different
• Inborn predispositions to consistently behave and react in a
certain way define temperament
• Most researchers agree that temperament has a genetic and
biological basis:
– although environment can modify a child’s basic temperament
• In the 1950’s Chess & Thomas rated young infants on a
variety of characteristics:
– such as activity level, mood, regularity, and attention span
Development During Infancy
and Childhood
About 2/3 of the babies could be classified into one of three broad
temperamental patterns: easy, difficult, and slow-to-warm-up
Easy babies – readily adapt to new experiences, generally display
positive moods and emotions, and have regular sleeping and eating
Difficult babies – tend to be intensely emotional, are irritable and
fussy, cry a lot, and tend to have irregular sleeping and eating patterns
Slow-to-warm-up babies – have a low activity level, withdraw from
new situations and people, and adapt to new experiences very
About 1/3 of the infants were characterized as average babies
because they did not fit neatly into one of these three categories
Characteristic ways of responding to the
environment that vary from infant to
(Data from Thomas, et al., 1970)
Development During Infancy
and Childhood
 Attachment: forming emotional bonds
– Attachment – the emotional bond that forms between
infant and caregivers, especially the mother
• According to attachment theory, an infant’s ability to thrive
physically and psychologically depends in part on the quality
of attachment
• In all cultures, the emotional bond between between infants
and caregivers is an important relationship:
– although there are cultural differences in how the attachment
relationship is conceptualized and encouraged
• Infants can form multiple attachments
Development During Infancy
and Childhood
 Depending on the parents, infants can form secure or
insecure attachments
– Secure attachment – occurs when parents are consistently warm,
responsive, and sensitive to their infant’s needs
– Insecure attachment – may develop when an infant’s parents are
neglectful, inconsistent, or insensitive to the infant’s moods or
 VIDEO – Attachment
– The Human Experience, segment 21
Development During Infancy
and Childhood
The most commonly used procedure to measure
attachment, called the “Strange Situation”, was
developed by Ainsworth
And is typically used with infants between 1-2 years old
1. The mother stays with the child for a few moments,
2. She then departs, leaving the child with the stranger
3. After a few minutes, mother returns, spends a few minutes in the
4. She then leaves, and returns again
Psychologists assess attachment by observing the infant’s behavior
toward the mother during the Strange Situation procedure
Development During Infancy
and Childhood
 The securely attached infant will use the mother as a “secure” base
from which to explore the new environment, periodically returning to
her side;
– Will show distress when mother leaves and will greet her warmly when
she returns.
– The mothers easily soothe securely attached babies
 An insecurely attached infant is less likely to explore the
environment, even when the mother is present and may appear either
very anxious or completely indifferent
– Such infants tend to ignore or avoid their mothers when they are present
• Some become extremely distressed when the mother leaves the
room and, when reunited,
– they are hard to soothe and:
– may resist their mothers’ attempt to comfort them
Development During Infancy
and Childhood
 Language development
By the time children reach three years of age, they
have learned:
a. approximately 3,000 words and:
b. the complex rules of their language
According to linguist Noam Chomsky, every child is
born with a biological predisposition to learn
language – any language
That is, they possess what he calls a “universal grammar”:
a basic understanding of the common principles of language
Development During Infancy
and Childhood
 At birth, infants can distinguish among the
speech sounds of all the world’s languages
 By 10 months, they distinguish only the
speech sounds that are present in the
language to which they have been exposed
Development During Infancy
and Childhood
 Motherese: encouraging language development
People in every culture use a style of speech called
motherese, or infant directed speech, with babies
Motherese is characterized by:
Distinct pronunciation,
A simplified vocabulary,
Short sentences,
A high pitch, and
Exaggerated intonation and expression
Development During Infancy
and Childhood
The cooing and babbling stage of language development
In virtually every culture, infants follow the same sequence of
language development, and at roughly similar ages
1. Around 3 months – infant begins to “coo”
1. Around 5 months – infant begins to “babble”
Infants all over the world use the same sounds when they babble,
• including sounds that do not occur in the language of their
parents and other caregivers
1. Around 9 months – infant begins to babble more in the sounds
specific to their language
Babbling seems to be a biologically programmed stage of language
Development During Infancy
and Childhood
 The one-word stage of language development
– Long before babies become accomplished talkers, they
understand much of what is said to them.
• Thus, they have a comprehension vocabulary (words they
understand) that is much larger than:
• their production vocabulary (the words they can say)
– Around their first birthday, infants produce their first real words
• Usually referring to concrete objects or people that are important to
the child
– Such as mama, dada, or ba-ba (bottle)
• During the one-word stage, babies use a single word and vocal
intonation to stand for an entire sentence
– “ba-ba = “I want my bottle”
Development During Infancy
and Childhood
 The two word stage of language development
– Around their second birthday, infants begin putting
words together to construct a simple “sentence”
• Such as “Mama go,” & “Where kitty,”
– These utterances include only the most essential
• but basically follow a grammatically correct sequence
– Children move beyond the two-word stage at around
2½ years of age
• Language production and comprehension increase
dramatically thereafter
Development During Infancy
and Childhood
 Gender-role development
Gender – refers to the cultural and social
meanings that are associated with maleness
or femaleness
a. Gender roles – behaviors, attitudes, and
personality traits that a given culture designates
as either masculine or feminine
b. Gender identity – a person’s psychological sense
of being male or female
Development During Infancy
and Childhood
 Between the ages of 2 and 3, children can
identify themselves and other children as boys or
– although the details are still a bit fuzzy for them
 From about 18 months to the age of 2 years, sex
differences in behavior begin to emerge
– Toddler girls play more with soft toys and dolls,
• and ask for help from adults more than toddler boys do
– Toddler boys play more with blocks and transportation
toys (trucks and wagons),
• and play more roughly
Development During Infancy
and Childhood
Explaining gender roles: Two contemporary theories
Social learning theory – gender roles are learned through
reinforcement, punishment, and modeling
Gender schema theory – children actively develop mental
categories/schemas (mental representations) for masculinity and
• Gender schemas:
Influence how people pay attention to, perceive, interpret, and
remember gender-relevant behavior
Seem to lead children to perceive members of their own sex
more favorably than members of the opposite sex
Help children to readily assimilate new information
Piaget’s Stages
According to Piaget, children progress through four
distinct cognitive stage
Sensorimotor (0-2 years)
Preoperations (2-7 years)
Concrete Operations (7-12 years)
Formal Operations (12 and up)
As a child progresses to a new stage, his/her thinking is
qualitatively different
Piaget’s Stages
 Understand the world
through senses and
motor actions
 Develop object
permanence – the idea
that an object still exists
even if it can’t be seen
 CD ROM: Obj. Perm.
Piaget’s Stages
Preoperative (“before
 Symbolic thought –
ability to use words,
images, and symbols to
represent the world
 Thinking is egocentric
(the inability to take
another person’s
Piaget’s Stages
Concrete Operations
 Can do logical
 Understand reversibility
 Can do conservation –
two equal quantities
remain equal even if the
appearance of one has
Piaget’s Stages
 Can do abstract &
Development During Infancy
and Childhood
 CD ROM: Piaget’s Conservation Task (#18)
 Studying Piaget’s theory
– Generally, scientific research has supported Piaget’s
most fundamental idea:
• That infants, young children, and older children use distinct
cognitive abilities to construct their understanding of the
– Other aspects of Piaget’s theory have been criticized
Development During Infancy
and Childhood
Three criticisms of Piaget’s theory
Inaccurate assessment of object permanence
Piaget’s stages are not as universal as he believed
Underestimation of the impact of the social and
cultural environment on cognitive development
Development During Infancy
and Childhood
Criticisms of Piaget’s theory
Today, many researchers believe that in assessing
object permanence during infancy, Piaget confused:
motor skill limitations with:
cognitive limitations
Bailargeon – used visual tasks, rather than manual tasks to
challenge Piaget’s belief regarding the age at which infants
acquire object permanence
3 ½ month-old infants looked longer at a carrot that cannot
be seen through a window
Showing object permanence much earlier than Piaget
Development During Infancy
and Childhood
Criticisms of Piaget’s theory
Piaget’s stages are not as universal as he believed
Researchers have found that many adults display abstracthypothetical thinking only in limited areas of knowledge,
And some adults never display formal operational thought
Some developmental psychologists emphasize the
information-processing model of cognitive development
Focuses on the development of fundamental mental
processes like attention, memory, and problem solving
Cognitive development is viewed as continuously changing
over the lifespan
Development During Infancy
and Childhood
Criticisms of Piaget’s theory
III. Piaget underestimated the impact of the social and
cultural environment on cognitive development
Russian psychologist Vygotsky believed that cognitive
development is strongly influenced by social and cultural
Such as the support and guidance that children receive from
parents, other adults, and older children
Cross-cultural studies show that cognitive development is
strongly influenced by:
the skills that are valued and encouraged in a particular
Vygotsky’s View
 Cognitive ability falls in the "Zone of
Proximal Development"
Zone of Proximal
without help
Kid’s performance
with help
A transitional stage between late childhood and the
beginning of adulthood, during which:
sexual maturity is reached
identity is explored
Physical and sexual development
Puberty – tends to follow a predictable sequence for each sex
1. Internally, puberty involves the development of the primary sex
• The sexual organs that are directly involved in reproduction,
such as the female’s uterus and the male’s testes
2. Externally, puberty involves the development of the secondary sex
• Characteristics not directly involved in reproduction, but still
signal sexual maturity
• Such as changes in height, weight, and body shape, appearance
of body hair, voice changes, and in girls, breast development
Some statistics:
Females are typically about two years ahead of males in terms of physical and
sexual maturation
The adolescent growth spurt – the period of marked acceleration in weight and
height gains
Menarche – a female’s first menstrual period, typically occurring around age 12
or 13
Occurs about two years earlier in females than in males
May take place as early as 9-10 or as late as 16-17
During early and middle adolescence, the physical changes of puberty:
Drive much of the adolescent’s interest in sexuality,
although social and cultural factors also have an influence
Age is a good predictor of when teenagers typically begin various sexual
 Social development
– As a general rule, when parent-child relationships
have been good before adolescence,
• they continue to be relatively smooth during adolescence
• However:
– Relationships with friends and peers become increasingly more
• Peer relationships tend to reinforce the traits and goals that
parents fostered during childhood
The Adolescent’s Peers
Give feedback on social behavior
Provide an objective standard for
Teach social skills
 Identity formation: Erik Erikson’s theory of
psychosocial development
Identity – a person’s definition or description of
himself or herself
Including values, beliefs, and ideals that guide the
individual’s behavior
Erikson’s theory of psychosocial development – consists
of eight stages throughout the lifespan
Believed that the key psychosocial conflict facing the
adolescent is identity versus identity diffusion
1. The adolescent’s path to successful identity
development begins with identity diffusion
2. This is followed by a moratorium period
3. Gradually, the adolescent arrives at an integrated
Erickson’s Stages of
Psychosocial Development
Trust vs. Mistrust
Autonomy vs. Shame & Doubt
Initiative vs. Guilt
Industry vs. Inferiority
Identity vs. Role Confusion
Intimacy vs. Isolation
Generativity vs. Stagnation
Integrity vs. Despair
Young Adult
Old Age
The development of Moral Reasoning
The aspect of cognitive development that has to do with the
way an individual reasons about moral decisions
The most influential theory of moral reasoning was proposed by
whose theory proposed three distinct levels of moral reasoning:
1. Preconventional - avoiding punishment/maximizing gain
2. Conventional - social roles, rules, and obligations
3. Postconventional - internalized legal and moral principles
Each level is based on the degree to which a person conforms to
conventional standards of society
Each level has two stages that represent different degrees of
sophistication in moral reasoning
The responses to children under 10 reflect
preconventional moral reasoning
Based on self-interest – avoiding punishment and maximizing
personal gain
2. Beginning in late childhood and continuing through
adolescence and adulthood, responses typically reflect
conventional moral reasoning
Emphasizes social roles, rules, and obligations
3. Postconventional moral reasoning is guided by
internalized legal and moral principles:
that protect the rights of all member of society
Kohlberg’s Theory
– Stage 5
31 -- Protecting
society is
and individual
is "right”is "right”
– Stage 6
42 -- Authorities
Universal benefits
& rulesthe
individual "right"
% Moral Statements
(Data from Kohlberg, 1963)
 Criticisms of Kohlberg’s theory
1. Research was done on all males, but theory was
applied to males and females
Gilligan – model is based on an ethic of individual rights
and justice, which is a more common perspective for males
She developed a model of women’s moral development that is
based on an ethic of care and responsibility
2. Some cross-cultural psychologists argue that
Kohlberg’s stories and scoring system reflect:
a Western emphasis on individual rights, harm, and justice
that is not shared in many cultures
Adult Development
 Physical changes
– Our unique genetic blueprint greatly influences the unfolding of
certain physical changes during adulthood
• Such changes vary significantly from one person to another
– For example, menopause (the cessation of menstruation that
signals the end of reproductive capacity in women) may occur
anywhere from the late thirties to the early fifties
– Staying mentally and physically active and eating a proper diet
can both slow and minimize the degree of physical decline
associated with aging
– Physical strength typically peaks in early adulthood (the 20’s and
• Strength and endurance gradually decline in middle
adulthood (40’s to mid 60’s)
• Physical strength and stamina decline further and faster
during late adulthood (mid 60’s on)
Adult Development
 Social development
– In his theory of psychosocial development, Erikson described
two fundamental themes that dominate adulthood: love and work
• According to Erikson, the primary psychosocial task of early
adulthood is to:
– form a committed, mutually enhancing, intimate relationship
with another person
• During middle adulthood, the primary psychosocial task becomes
one of generativity:
– The need to contribute to future generations through your
children, your career, and other meaningful activities
Adult Development
 The focus of adult friendships is somewhat
different for men and women
– Female friends tend to:
• confide in one another about their feelings, problems, and
interpersonal relationships
– Male friends typically:
• minimize discussions about relationships or personal feelings
or problems;
– Instead, male friends tend to do things together that they find
mutually interesting,
• such as activities related to sports or hobbies
Adult Development
 Establishing a committed relationship takes on a
new urgency in adulthood:
– getting married and starting a family are the traditional
tasks of early adulthood
• Today, young adults are postponing marriage so they can
finish their education and establish a career
– As a general rule, we tend to be attracted to and marry
people who are similar to us on a variety of
• Including physical attractiveness, social and educational
status, ethnic background, attitudes, values, and beliefs
Age of First Marriage
(Data from Census Bureau, 1994)
Adult Development
 The transition to parenthood
– Marital satisfaction tends to decline after the
birth of the first child
• It tends to rise again after the children leave home
Adult Development
 The nature of intimate relationships and family
structures varies widely in the US
– In the 1990’s well over 3 million unmarried couples
were living together
– More than half of all first marriages end in divorce
• Thus, remarrying and starting a second family is not unusual
– It may be that any relationship that promotes the
overall sense of happiness and well-being for the
people involved is a successful relationship
U.S. Households
Reasons for Divorce
Adult Development
Careers in adulthood
Researchers have found that close to 1/3 of people in their late
twenties and early thirties:
do not just change jobs within a particular field,
but completely switch occupational fields
Dual-career families have become increasingly common
Multiple roles seem to provide both men and women with a
greater potential for:
increased feelings of self-esteem, happiness, and competence;
• The critical factor is not the number of roles that people take on,
but the quality of experiences on the job, in the marriage, and as
a parent
Late Adulthood and Aging
 The average life expectancy:
– for men is about 72 years old;
– for women, it is about 79 years
 The majority of older adults live healthy, active,
and self-sufficient lives
 The number of older adults in the US has been
gradually increasing over the past several
Late Adulthood and Aging
 Cognitive changes
– Psychologist Schaie and his colleagues have
conducted longitudinal studies:
• following some 5,000 people as they have aged to learn what
happens to intellectual abilities
– Schaie’s findings: general intellectual abilities gradually
increase until the 40’s,
• Then become relatively stable until about 60,
• When a small but steadily increasing percentage of older
adults experience slight declines on tests of general
intellectual abilities
– Schaie found that those who were better educated and engaged
in physical and mental activities throughout older adulthood:
• showed the smallest declines in mental abilities
Late Adulthood and Aging
 Social Development
– The activity theory of aging
• Psychosocial theory that life satisfaction in late adulthood is highest
– people maintain the level of activity they displayed earlier in life
– Along with satisfying social relationships, the prescription for
psychological well-being in old age:
• includes achieving what Erikson called Ego Integrity
– The feeling that one’s life has been meaningful, vs.
• Despair – feelings of regrets or bitterness about past mistakes,
missed opportunities, or bad decisions; a sense of disappointment
in life
– Often the themes of ego integrity or despair emerge as older
adults engage in life review
• Thinking about or retelling their life story to others
Living Arrangements
Living Arrangements
The Final Chapter: Dying and
 Attitudes toward dying and death are as
diverse in late adulthood as they are
throughout the lifespan
– In general, anxiety about death tends to peak
in middle adulthood,
• then decrease in late adulthood
The Final Chapter: Dying and
Elisabeth Kubler-Ross interviewed over 200 terminally
ill patients and proposed that the dying go through five
Denial of death
Anger at the notion of dying
Bargaining – making a “deal” with doctors, relatives, or God
Further research indicates that individuals who are
dying do not progress through a predictable sequence of
Dying is as individual a process as is living
• People cope with the prospect of dying much as they have
coped with other stresses involved in living