Developmental Psychology

Examines how people are continually developing in physical, cognitive, and social ways.

Main Concepts in this Chapter -

  1. Nature vs. Nurture
  2. Continuity and Stages
  3. Stability and Change

Prenatal Development


200 million or more deposited sperm begin their race upstream, approaching a cell 85,000 times their own size.

After the egg has been fertilized by the sperm, the two fuse together, and becomes a zygote. About 10 days after conception, the zygote attaches to the mother’s uterine wall, which starts developing as an embryo. By 9 weeks after conception, the embryo looks unmistakably human and is now referred to as a fetus.

Infancy and Childhood

The Competent Newborn

Habituation is when a novel stimulus gets attention at first, but the more often its presented, the weaker the response becomes.

Newborns will turn their heads towards the sound of human voices and will gaze longer at human faces, a form of social responsiveness.

Attachment with mother is important as a newborn, which can be established through breastfeeding. By three weeks, the newborn will recognize their mother's odor and voice.

Brain Development

As seen in brain scans, the brain develops rapidly, creating and strengthening neural connections.

Motor Development

Cognitive Development

schemas: concepts or mental molds into which we pour experiences

assimilate: new experiences — a child thinks any four legged animal is a cow because they learned about the cow first

accommodate: adjusting our schemas to incorporate info provided by new experiences

Piaget's Theory

Studies around the globe have confirmed that human cognition unfolds basically in the sequence Piaget described, however, most psychologists believe that cognitive development is more continuous rather than set-in-stone stages.

Social Development

stranger anxiety: the fear of strangers that infants commonly display, beginning by about 8 months of age


attachment: an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation.

- Body Contact

- Familiarity -- Critical period, Imprinting, Sensitive period

Erikson's Theory of Social Development

Parenting Styles

Authoritarian parents impose rules and expect obedience (“Do it, because I said so.”)

Permissive parents submit to their children’s desires, make few demands, and use little punishment

Authoritative parents are both demanding and responsive

Gender Development

Gender: the biological + social characteristics by which people define male or female

Men + women are in most ways alike; similar genetic make-up; among our 46 chromosomes, 45 are unisex; similar levels of intelligence, vocabulary + happiness

Gender is also socially constructed.

  • Gender roles-our expectations about the way men and women should behave—vary across cultures and time, as well as across generations
  • However, gender roles are not definitive.

Parents and Peers

  • Preschoolers who disdain a certain food often will eat that food if put at a table with a group of children who like it.
  • Children who hear English spoken with one accent at home and another in the neighborhood and at school will invariably adopt the accent of their peers, not their parents.
  • Teens who start smoking typically have friends who model smoking, suggest its pleasures, and offer cigarettes. Part of this peer similarity may result from a selection effect, as kids seek out peers with similar attitudes and interests. Those who smoke (or don’t) may select as friends those who also smoke (or don’t).


Adolescence: the transition period from childhood to adulthood

Physical Development

puberty: the time when we mature sexually (become capable of reproduction)

  • Primary sex characteristics: develop dramatically (reproductive organs + external genitalia)
  • Secondary sex characteristics: breasts + hips in girls, facial hair + deepened voice in boys, pubic + underarm hair in both sexes

Cognitive Development

The ability to reason hypothetically + deduce consequences, to detect inconsistencies in others’ reasoning and to spot hypocrisy

Kohlberg's Theory of Moral Development

Social Development

As one enters into the adolescence stage of development, the question "Who Am I?"is asked in order to form their identity.

Most will find their true identity by the time they are in college.

They may adopt some of their parents values and beliefs, but their peers also have an influence.


Physical Development

Sensory Abilities

  • Declining vision, muscle strength, reaction time, stamina, hearing, and the sense of smell
  • Less light reaches the retina (reading + driving)


  • Bad news: the immune system weakens, making life-threatening ailments more likely
  • Good news: fewer short term ailments due to a lifetime of accumulated antibodies (flu + colds)
  • Neural processes slow, and compared with teens + young adults, older people take a bit longer time to…
  • React, solve perceptual puzzles, and to remember names
  • By age 80, brain weight reduction of 5%
  • Atrophy of frontal lobes means blunt comments/questions
  • Exercise helps

Cognitive Development

crystallized intelligence: our accumulated knowledge and verbal skills; tends to increase with age

fluid intelligence: our ability to reason speedily and abstractly; tends to decrease during late adulthood.

Social Development

As people enter their 40’s, they undergo a midlife transition to middle adulthood, which can be a crisis.

The social clock—the culturally preferred timing of social events such as marriage, parenthood, + retirement—varies from era to era and culture to culture

Marital Commitment

Monica Hamilton Photography

Marriages are more likely to last when couples marry after age 20 + are well educated.

Compared with their counterparts of 40 years ago, people in Western countries are better educated + marrying later…but, they are nearly twice as likely to divorce.

Occupational Commitment

Choosing a career path is difficult, especially in today’s changing work environment, and it takes time for people to settle into an occupation.

In the end, happiness is…

  • having work that fits your interests and provides a sense of competence + accomplishment
  • Having a close, supportive companion who cheers your accomplishments
  • For some, it includes having children who you love + whom love you and feel proud of

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