PSY 100 General Psychology
Lecture Guide 6: Lifespan Development
Michael L. Thomas, PhD
1 Introduction and Learning Objectives
🎥 Watch this before starting!
3 Moral Development
Jean Piaget was not only interested in cognitive development—he also explored how children come to understand moral concepts such as fairness, justice, and rules. Building on Piaget’s foundational ideas, Lawrence Kohlberg developed a more detailed and structured theory of moral development, which he organized into three levels, each containing two stages.
To investigate moral reasoning, Kohlberg presented subjects with hypothetical moral dilemmas, the most famous being the Heinz dilemma:
“A woman was near death from a particular type of cancer. Doctors said that a new drug might save her. The drug had recently been discovered by a local pharmacist, and while the drug itself was inexpensive to produce, the pharmacist was charging ten times what it cost to make. He had invested a great deal of money in developing the drug and wanted to recoup his costs. He was selling the drug for $2,000, even though it cost him only $200 to make. The sick woman’s husband, Heinz, went to everyone he knew to borrow money, but he could only raise $1,000. He explained to the pharmacist that his wife was dying and asked if he could buy the drug at a lower price or pay the rest later. But the pharmacist refused, saying, ‘I discovered the drug and I’m going to make money from it.’ Heinz became desperate and broke into the pharmacy to steal the drug for his wife. Was he right to do so?”
🍅 Note: This has nothing to do with the famous ketchup brand. Heinz is just a the character in the story.
Kohlberg emphasized that the reasoning behind the answer was more important than whether the participant said “yes” or “no.”
Level 1: Preconventional Morality
Morality is externally controlled. Children accept rules set by authority figures and judge actions by their consequences.
Stage 1: Punishment Orientation
Behavior is driven by the desire to avoid punishment.
“If I get caught, I’ll be punished.”Stage 2: Reward Orientation
Right action is defined by what is in one’s own best interest or involves equal exchange.
“If you help me, I’ll help you.”
Level 2: Conventional Morality
Morality is tied to personal and societal relationships. People strive to obey rules and social norms to gain approval or maintain order.
Stage 3: Good Boy/Good Girl Orientation
Behavior is guided by the desire to be seen as a “good” person by others.
“He shouldn’t steal the drug because people will think he’s a criminal.”Stage 4: Authority and Social Order Orientation
Morality is based on maintaining law and order and fulfilling one’s duties.
“Stealing is against the law, and laws must be upheld to avoid chaos.”
Level 3: Postconventional Morality
Morality is based on abstract reasoning and universal ethical principles. Laws are important, but not absolute.
Stage 5: Social Contract Orientation
Right and wrong are determined by societal agreement and concern for the greater good.
“Although the law prohibits stealing, saving a life justifies breaking the law.”Stage 6: Universal Ethical Principles
Moral reasoning is guided by internalized and self-chosen ethical principles, such as justice, dignity, and equality.
“Human life has more value than property. I must act based on what is ethically right.”
🤖 How Would AI Respond?
Try posing the Heinz dilemma to your favorite AI chatbot how it would respond?
It should be noted that several criticisms have been made about Kohlberg’s theory. These include:
- Cultural Bias: Kohlberg’s model reflects Western, individualistic values—particularly the emphasis on justice and individual rights.
- Gender Bias: Psychologist Carol Gilligan criticized Kohlberg’s theory for being male-centered, arguing that it undervalues moral reasoning based on care, compassion, and relationships—qualities often emphasized more in female moral reasoning.
🌐 Watch this! Follow this link to a YouTube video where Professor Marie Coppola interviews children of different ages responding to the Heinz dilemma. As you watch the video, try to determine which level of moral reasoning each child uses.
4 Gender Development
Although the word gender originates from the Latin genus, meaning kind or type, its modern scientific—and often popular cultural—use refers to the social, cultural, and psychological meanings and expectations associated with masculinity, femininity, and other gender identities. Today, many scientists and scholars understand gender as a spectrum rather than a binary, recognizing that traits associated with masculinity, femininity, and gender identities themselves are diverse and not limited to two distinct categories. Although the idea of a gender spectrum is relatively new in mainstream discourse, non-binary gender identities have long existed. As one example, the word tomboy—used to describe a girl or woman who displays traditionally masculine traits—has been part of the English vernacular for over 400 years.
Sex, on the other hand, is a biological classification typically assigned at birth based on physical characteristics (e.g., reproductive organs and presumed or verified sex chromosomes). Sex is traditionally categorized as male or female, but intersex is also recognized as a natural biological variation.
Gender is shaped, in part, by gender roles—culturally defined behaviors, traits, and responsibilities expected of individuals based on their perceived or assigned gender. These roles vary across time and culture. Gender is also shaped by a person’s gender identity—a deeply felt internal sense of their own gender, which may or may not align with their sex assigned at birth or the gender others perceive them to be.
Social learning theories emphasize the influence of external rewards, punishments, and observational learning in shaping gender-related behavior. According to this perspective, children learn gender roles by watching others and by receiving feedback for behaving in ways that are considered sex-appropriate in their cultural context. For example, a child may be praised for playing with toys traditionally associated with gender norms for their sex or discouraged from engaging in behaviors perceived as inconsistent with gender norms.
These theories suggest that role models—such as parents, peers, teachers, and media figures—play a central role in reinforcing gendered behavior. Over time, children internalize these behavioral expectations, shaping their gender expression and understanding of social norms related to masculinity and femininity.
Cognitive-developmental theories, originally influenced by the work of Jean Piaget and later expanded by Lawrence Kohlberg, focus on how children actively construct gender understanding through cognitive growth. As children develop cognitively, they begin to form concepts of gender and apply these concepts to themselves and others.
A key idea in this framework is gender constancy—the understanding that one’s gender is stable over time and across situations. Many children achieve this understanding around ages 5 to 7 and may become motivated to adopt behaviors that align with their gender identity. However, it’s important to note that not everyone experiences gender as fixed, and many individuals identify in ways that are fluid or outside traditional categories.
Another important concept is Sandra Bem’s gender schema theory, which proposes that children develop mental frameworks—or schemas—related to gender. These schemas help children interpret and organize information about the world in terms of gender categories (e.g., “toys for boys” vs. “toys for girls”) and guide their own behavior to be consistent with these categories.
Gender can play a complex role in people’s lives. For many, gender identity fosters a strong sense of self and connection to community. At the same time, widely shared cultural expectations about masculinity and femininity—pancultural gender stereotypes—can influence how individuals are perceived and treated. Historically, and in many societies, gender norms have also been linked to limitations on social, political, and occupational opportunities, particularly for women.
🌐 Want to know more? OPTIONAL Follow this to a collection of TED talks on the topic of gender.
5 Health Throughout the Lifespan
As people age, all 11 organ systems of the human body experience changes. The skin develops wrinkles and age spots, and hair loss becomes more common. Muscle mass decreases, and bones lose density and marrow. The heart and blood vessels stiffen, leading to a lower maximum heart rate and increased risk of hypertension and cardiovascular disease. Lung function declines due to a weaker diaphragm and changes in the structure of the air sacs. The digestive system weakens, with slower esophageal function and structural changes in the stomach, liver, and pancreas—constipation also becomes more common. Kidney efficiency declines, making older adults more vulnerable to dehydration and the side effects of medications. Hormonal changes impact reproductive systems in both men and women. The endocrine system shows reduced hormone production and sensitivity, while the immune system becomes less effective. Finally, the nervous system also changes with age—an area especially important for understanding brain and cognitive health.
Superficially, age-related changes often cause concern and have contributed to a booming cosmetics and hormone replacement industry. These natural physical changes have also fueled negative and harmful aging stereotypes, which portray older adults as physically frail and mentally sluggish. In reality, aging is far from a one-way street to decline. While physical health does tend to decline over time, there is considerable interindividual variability, and several lifestyle changes can help slow this process. Moreover, mental health often improves in meaningful ways. Watch the video below where I share some of my own research on this topic.
These findings are not unique to our group. Many studies of aging have found similar results.
A quick note about cognition. While cognition is perhaps the most frequently discussed aspect of mental health in aging, the relationship between cognition and age is complex. While older adults often show natural declines in time-pressured problem-solving tasks after middle adulthood, they typically demonstrate continued growth in vocabulary and general knowledge throughout most of the lifespan. In other words, not all aspects of cognitive functioning decline with age. Some improve.
While the phrase “older but wiser” may be an overgeneralization that feeds into general aging stereotypes, research does suggest that older adults are generally better at regulating negative emotions and possess greater accumulated knowledge compared to younger adults.
6 Brain Aging and Neurodegenerative Disease
As noted above, the nervous system undergoes systematic changes with age, just like all other organ systems. After increasing in size throughout childhood, adolescence, and early adulthood, brain weight reaches its peak in the late 20s and then steadily declines thereafter. These declines in overall brain weight are largely due to thinning and synaptic pruning. However, pathological processes can lead to accelerated brain atrophy.
Dementia is a general term for the loss of memory, language, problem-solving, and other cognitive abilities severe enough to interfere with daily life. While dementia can be caused by sudden brain trauma, it is more often an insidious process in which the brain experiences progressive cell death over a period of years to decades. There are various types of dementia, with the most common being Alzheimer’s disease and vascular dementia.
Alzheimer’s disease is caused by the formation of abnormal protein aggregates called amyloid plaques and neurofibrillary tangles. The exact cause of Alzheimer’s disease is not well understood, and there is currently no cure. The likelihood of developing Alzheimer’s disease increases significantly after age 65, with risk doubling approximately every five years. By age 85, the estimated risk reaches nearly one in three.
Vascular dementia is caused by reduced blood flow to the brain (e.g., strokes), often related to cardiovascular risk factors such as hypertension, diabetes, and stroke. Strokes are often thought of as life-threatening medical events with obvious symptoms. However, the video below highlights the risk of mini-strokes—also known as transient ischemic attacks—which may go unnoticed but can still have a significant impact on brain aging.
🧠 Watch this! Follow this link to a YouTube video reporting the results of weekly brain scans for older an adult.
Fortunately, research has shown that you can reduce your risk of developing dementia by following healthy lifestyle habits, including getting adequate sleep, limiting drug and alcohol use, eating a balanced diet, and exercising regularly.
7 Summary
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2 Social Development
Erik Erikson (1902–1994) was a German-American developmental psychologist and psychoanalyst best known for his theory of psychosocial development. Erikson proposed a lifespan model of development that emphasizes the role of social and cultural factors in shaping human growth.
Erikson’s theory incorporates Darwinian principles, suggesting that the drive to form social relationships is evolutionarily adaptive—promoting individual survival and reproductive success. These innate social drives are considered biologically based but expressed through culture, meaning how they unfold can vary depending on societal context.
Erikson further assumed that successful development depends on resolving specific psychosocial conflicts (crises) that emerge at different points in life. He divided the lifespan into eight stages, each defined by a central conflict or crisis that individuals must resolve. These stages are sequential, meaning unresolved issues from earlier stages can impact later development. Each stage is characterized by a developmental “task” involving a conflict between two opposing outcomes (e.g., trust vs. mistrust in infancy). These eight stages are as follows:
The outcome of each stage is not binary but exists along a continuum from positive to negative. Successfully resolving a stage leads to the development of a psychosocial strength or virtue (e.g., hope, will, purpose). Failure to resolve the stage may result in psychological difficulties or maladaptive behaviors, which can be revisited and potentially resolved later in life.