Chapter 11: Human Development Across the Life Span
development - the sequence of age-related changes that occur as a person progresses from conception to death.
Progress before Birth: Prenatal Development
zygote - a one-celled organism formed by the union of a sperm and an egg.
the prenatal period - extends from conception to birth, usually encompassing nine month of pregnancy.
1.The Course of Prenatal Development:
a) Germinal Stage:
germinal stage - the ﬁrst phase of prenatal development,encompassing the ﬁrst 2 weeks after conception.
• it begins when a zygote is created through fertilization
rapid cell division begins after 36 hours
• the mass of cells migrates along the mother’s fallopian tube to the uterine cavity
• on about the 7th day,the cell mass begins to implant itself in the uterine wall
• many zygotes are rejected at this point
• the placenta begins to form during the implantation process
placenta - a structure that allows oxygen and nutrients to pass into the fetus from the mother’s bloodstream, and bodily
wastes to pass out to the mother
• this exchange takes place across thin membranes that block the passage of blood cells,keeping the fetal and maternal
b) Embryonic Stage:
embryonic stage - the 2nd stage of prenatal development, lasting from 2 weeks until the end of the 2nd month.
• most of vital organs and bodily systems begin to form in the developing organism
• structures like the heart,spine, and brain emerge
• arms,legs,hands,feet,ﬁngers,toes,eyes,and ears are already discernible
• this stage is a period of great vulnerability because all of the basic physiological structures are being formed
• most miscarriages occur during this period
• most major structural birth defects are also due to problems that occur during this stage.
c) Fetal Stage:
fetal stage - the 3rd stage of prenatal development,lasting from 2 months through birth.
• ﬁrst 2 months of this stage bring rapid bodily growth,as muscles and bones begin to form
• the fetus is capable of movement as skeletal structures harden
• sex organs start to develop during the 3rd month • brain cells multiply at a brisk pace during the ﬁnal 3 months
• a layer of fat is deposited under the skin to provide insulation,and the respiratory and digestive systems mature
• sometime b/w 22 weeks and 26 weeks the fetus reaches the age of viability - the age at which a baby can survive in the
event of a premature birth.
2. Environmental Factors and Prenatal Development:
a) Maternal Nutrition:
• too much or too little weight gain during gestation is associated with a variety of birth complications
• the eﬀects of severe maternal malnutrition are a major problem in underdeveloped nations where food shortages are
• prenatal malnutrition may have negative eﬀects decades after a child’s birth(ex. increased vulnerability to psychiatric
disorders in adolescence and adulthood).
b) Maternal Drug Use:
• most drugs consumed by a pregnant woman can pass through the membranes of the placenta
• babies of heroin users are born addicted to narcotics and have an increased risk of early death due to prematurity,birth
defects,respiratory diﬃculties,and problems associated with their addition.
• prenatal exposure to cocaine is associated with increased risk of birth complications and a variety of cognitive deﬁcits
that are apparent in childhood.
• prenatal marijuana exposure may be linked to disturbances in executive functioning associated with the prefrontal part
of the brain at age 3
• problems can also be caused by a great variety of drugs prescribed for medical reasons, and the impact varies depending
on the drug,the dose,and the phase of prenatal deveopment.
fatal alcohol syndrome - a collection of congenital(inborn) problems associated with excessive alcohol use during
• typical problems include microcephaly(small head),heart defects,irritability,hyperactivity,and delayed mental and
• most common known cause of mental retardation
• smoking produces a number of physiological changes in the mother that appear to reduce the ﬂow of oxygen and
nutrients to the fetus.
• smoking appears to increase a mother’s risk for miscarriage,stillbirth,and prematurity,and newborns’ risk for sudden
infant death syndrome.
c) Maternal Illness:
• diseases such as rubella,syphilis,cholera,smallpox,mumps,and even severe cases of ﬂu can be hazardous to the fetus
• the nature of any damage depends on when the mother contracts the illness
• genital herpes and AIDS are very deadly diseases that pregnant women can transmit to the fetus.
• genital herpes is transmitted during the birth process itself and can cause microcephaly,paralysis,deafness,blindness,
and brain damage in infants and is fatal for many newborns. • about 20%-30% of pregnant women who carry AIDS pass the disease on to their babies,although approved antiviral
drugs can reduce this percentage.
• good quality medical care that begins early in pregnancy is associated with reduced prematurity and higher survival
rates for infants.
The Wondrous Years of Childhood
1.Exploring the World: Motor Development:
motor development - the progression of muscular coordination required for physical activities.
the cephalocaudal trend - the head-to-foot direction of motor development.
• children gain control over the upper part of their bodies.
the proximodistal trend - the centre-outward direction of motor development.
• children gain control over their torso before their extremities(ex. infants reach for things by twisting their entire
body,but gradually learn to extend just their arms).
• infants typically grow to roughly triple their birth weight during the 1st year,while height increases by about 45%.
maturation - development that reﬂects the gradual unfolding of one’s genetic blueprint.
• it’s a product of genetically programmed physical changes that come with age-as opposed to experience and
• the driving force behind motor development is infants’ ongoing exploration of their world and their need to master
• progress in motor development is attributed to infants’ experimentation and their learning and remembering of the
consequences of their activities.
a) Understanding Developmental Norms:
developmental norms - indicated the median age at which individuals display various behaviours and abilities.
• they are useful as long as parents don’t expect their children to progress exactly at the pace speciﬁed in the norms;
variations from the typical age of accomplishment are entirely normal.
b) Cultural Variations and Their Signiﬁcance:
• relatively rapid motor development has been observed in some cultures that provide special practice in basic motor
skills, and vice versa.
• some motor skills might be unique to the culture the child is being raised in.
2. Easy and Diﬃcult Babies: Diﬀerences in Temperament: temperament - characteristic mood,activity level,and emotional reactivity.
• infants show consistent diﬀerences in emotional tone,tempo of activity,and sensitivity to environmental stimuli very early
longitudinal design - in it, investigators observe 1 group of participants repeatedly over a period of time.
• in this type of study of development b/w ages 6 and 10,the same children would be observed at 6,again at 8,and
again at 10.
cross-sectional design - in it,investigators compare groups of participants of diﬀering age at a single point in time.
• in this type of study of development b/w ages 6 and 10, a group of 6-year-olds,a group of 8-year-olds,and a group of
10-year-olds would be compared simultaneously.
3.Early Emotional Development: Attachment:
attachment - the close,emotional bonds of aﬀection that develop between infants and their caregivers.
separation anxiety - emotional distress seen in many infants when they are separated from people with whom they have
formed an attachment.
• peaks around 14 to 18 months
• according to Bowlby’s view, infants are biologically programmed to emit behaviour(smiling,cooing) that triggers an
aﬀectionate,protective response from adults.
adults are programmed evolutionary to respond with warmth,love,and protection.
a) Patterns of Attachment:
• the unfolding of attachment depends on the interaction between a mother and an infant
• attachment relationships fall into 4 categories:
1. Secure attachment - children play and explore comfortably with their mother present,become visibly upset when she
leaves,and are quickly calmed by her return.
2.Anxious-ambivalent attachment - children appear anxious even when their mother is near and protest excessively
when she leaves,but they’re not calmed when she returns.
3.Avoidant attachment - children seek little contact with their mother and often are not distressed when she leaves.
4.Disorganized-disoriented attachment - children appear confused about whether they should approach or avoid their
mother and are especially insecure.
• the type of attachment that emerges b/w an infant and mother may depend on the nature of the infant’s temperament as
well as the mother’s sensitivity.
• based on their attachment experiences,children develop internal working models of the dynamics of close relationships
that inﬂuence their future interactions with a wide range of people.
• infants with secure attachment tend to become toddlers with high self-esteem; preschoolers displaying persistence,
curiosity,leadership; adults tend to have healthier intimate relationships.
b) Daycare and Attachment: • babies who receive non-maternal care for more than 20 hours per week have an increased risk of developing insecure
attachments to their mothers.
• given deprived child-rearing conditions found in many homes,there is evidence that daycare can have beneﬁcial eﬀects
on some youngsters’ social development.
c) Culture and Attachment:
• studies done in non-Western countries suggest that attachment is a universal feature of human development because it
develops around the same time anywhere in the world.
• some studies have found cultural variations in the 3 attachment categories - compared with children in the US, children
in Germany have higher avoidant attachment rates,while children in Japan-lower.
• researchers have attributed these disparities in attachment patterns to cultural variations in child-rearing practices.
d) Evolutionary Perspective on Attachment:
• attachment contributes to parents’ and children’s reproductive ﬁtness
• Example: if parents expect to pass their genes on to future generations,they need to raise their oﬀspring to
reproductive age and help them develop the social maturity required for successful mating.
4. Becoming Unique: Personality Development:
events in early childhood leave a permanent stamp on adult personality
• Erikson theorized that personality continues to evolve over the entire life span
• stages theories assume that (1) individuals must progress through speciﬁed stages in a particular order because each
stage builds on the previous one, (2) progress through these stages is strongly related to age, and (3) development is
marked by major discontinuities that usher in dramatic transitions in behaviour.
a) Erikson’s Stage Theory:
• he partitioned the life span into eight stages,each of which brings a psychological crisis involving transitions in
important social relationships.
• according to him,personality is shaped by how individuals deal with these psychological crises.
✴ see Erikson’s Stage Theory table
b) Evaluating Erikson’s Theory:
• the strength of this theory is that it accounts for both continuity and transition in personality development
one weakness is that the theory provides an “idealized” description of “typical” developmental patterns
• it’s not well suited for explaining the enormous personality diﬀerences that exist among people
5.The Growth of Thought: Cognitive Development:
cognitive development - the transitions in youngsters’ patterns of thinking,including reasoning,remembering,and
• Jean Piaget created the cognitive development stage theory a) Overview of Piaget’s Stage Theory:
• he proposed that youngsters progress through 4 major stages of cognitive development
✴ See Piaget’s Stage Theory table
according to him, children progress in their thinking through the complementary processes of assimilation and
assimilation - interpreting new experiences in terms of existing mental structures without changing them.
accommodation - changing existing mental structures to explain new experiences.
b) Evaluating Piaget’s Theory:
• his theory views infant development as a relatively discontinuous process composed,instead of a series of discrete stages
• in many ares,Piaget appears to have under-estimated young children’s cognitive development
• his model suﬀers from problems that plague most stage theories(little to say about individual diﬀerences)
• he believed that his theory described universal processes that should lead children everywhere to progress through
uniform stages of thinking at roughly the same ages
c) Neo - Piagetian Theories:
• Pascual-Leone found that the complexity that children could deal with varied positively across age
• he developed the concept of M-capacity,which relates to the maximum number of mental concepts that an individual
can keep in mind at one time.
• UofT’s Robbie Case argued that there are 4 major stages of cognitive development but that each stage is assumed to
have its own distinct structure and cognitive operation
• he further argues that,while cognitive development proceeds in line with Piaget’s stage view of progression,there is
a distinct set of cognitive skills involved that may show uneven development - children may show higher levels of
development in some domains than others.
d) Vygotsky’s Sociocultural Theory:
• Piaget’s and Vygotsky’s theories diﬀer in several important respects:
• in Piaget’s theory,cognitive development is primarily fueled by individual children’s active exploration,while in
Vygotsky places emphasis on how children’s cognitive development is fueled by social interactions.
• Piaget viewed cognitive development as a universal process,while Vygotsky asserted that culture exerts great
inﬂuence over how cognitive growth unfolds.