Chapter 17 Adolescent Development

Adolescence

The developmental transition between childhood and adulthood. It’s usually marked by puberty, meaning the biological changes that lead to an adult-sized body and sexual maturity. The slides frame it as roughly ages 10–20, but also point out people argue about when it “ends.”

Puberty

The physical transition that biologically “launches” adolescence. It includes hormonal changes that drive rapid growth and sexual maturation, and it produces primary + secondary sexual characteristics. Timing varies a lot person-to-person.

Primary sexual characteristics:
Body parts and functions that are directly involved in reproduction. These are the reproductive organs and related structures that allow sexual reproduction (like the ovaries/uterus in typical female development and the testes/penis in typical male development). They’re basically the “reproductive system” changes of puberty.

Lecture 18 Gender (1)

Secondary sexual characteristics:
Physical changes that aren’t directly part of reproduction, but develop during puberty and are associated with sexual maturity. These are things like breast development, widening hips, facial/body hair growth, voice deepening, and changes in body fat/muscle distribution. They often matter socially because they change how someone looks and how others perceive them.

Growth hormone (puberty)

A hormone that increases during puberty and supports tremendous gains in body size (basically the growth spurt). It’s part of why physical change can feel fast and intense in adolescence.

Estrogen + progesterone

Major sex hormones that guide many typical aspects of female pubertal development, including reproductive maturation and changes in the body during adolescence.

Androgens (testosterone)

Sex hormones, especially testosterone, that guide many typical aspects of male pubertal development, including reproductive maturation and other physical changes during adolescence.

Continuous vs. discontinuous development

Continuous development means change is gradual and builds smoothly over time (like steady growth or skill improvement). Discontinuous development means change happens in more noticeable shifts or stages (like sudden jumps). Puberty can be framed as both: hormones gradually change, but the outward physical changes can feel sudden.

Storm and Stress (theory of adolescence)

The idea that adolescence often involves more emotional intensity and more challenges with self-control compared to childhood or adulthood. It doesn’t mean every teen is “a mess,” but it tries to explain why conflict, mood swings, and risky behavior can be more common during this period—especially in high-pressure or high-peer situations.

Storm-and-stress can feel real in adolescence because your biology is kind of temporarily mismatched. Puberty hormones ramp up, and brain circuits tied to reward + social approval (dopamine-heavy pathways and “emotion” regions like the amygdala/limbic system) become more reactive, so excitement, embarrassment, and rejection hit harder. At the same time, the prefrontal cortex—the part that supports planning, impulse control, and weighing long-term consequences—is still maturing t

“Storm” (in storm & stress)

A dip in consistent self-control—meaning it’s easier for impulses to win, especially when something feels exciting, scary, or socially important. The person may still know what the “right choice” is, but acting on it can be harder in the moment.

• Self-control is still developing and improving overall, but it’s not consistent yet.

• Impulses/rewards/emotions can “override” it more easily, especially in real-life situations that are intense (peer pressure, excitement, anger, embarrassment, stress).

• So in the moment, it can look like self-control dropped because impulsivity wins more often, even though your ability to reason is actually getting better.

“Stress” (in storm & stress)

increased emotional sensitivity and emotional intensity. Social feedback like embarrassment, rejection, or approval can feel stronger, which can lead to bigger reactions and more mood variability compared to childhood.

Three main areas of storm & stress

(1) Increased desire for independence and autonomy, (2) changes in emotions (stronger feelings + sensitivity), and (3) impulse control challenges. These are basically the three “zones” where adolescent behavior often shifts the most.

Growth hormone (in puberty)

A hormone that rises during puberty and supports the adolescent growth spurt. It helps explain why teens can gain height and body size so quickly over a relatively short time.

Primary sexual characteristics

Physical developments directly involved in reproduction (the reproductive system and biological capacity for sexual maturity). These changes are a core part of what makes puberty “puberty,” not just cosmetic changes. Does nt have to be physically apparent

• Typically female: ovaries, uterus, vagina (and the internal reproductive system developing/maturing)

• Typically male: testes, penis, scrotum (and the reproductive system maturing, like sperm production)

Secondary sexual characteristics

Physical changes that are associated with sexual maturity but not directly part of the reproductive system. They’re still important because they affect appearance, social perception, and often self-image during adolescence.

Individual differences in pubertal timing

People enter and progress through puberty at different times. That matters because being earlier or later than peers can shape confidence, social status, stress, and how adults/peers interpret your behavior

Cognitive changes in adolescence

Adolescent thinking becomes more abstract and complex. Teens improve in attention, memory, and processing speed, and they also get better at thinking about their own thinking. This helps explain why adolescents can argue more logically than kids—but still sometimes make choices that don’t match their reasoning ability.

Prefrontal cortex (front of the brain): this region is still developing, and it’s the main “control center” for planning, reasoning, weighing consequences, and impulse control. That’s why judgment can be smart in theory but inconsistent in the moment.

Emotion/reward systems (dopamine + limbic areas): the brain’s reward circuitry becomes more reactive to novelty and social reward, which can make exciting things feel extra motivating.

Amygdala (emotion processing): this area is heavily involved in fast emotional reactions (like fear/anger/embarrassment) and develops earlier/rapidly compared to the prefrontal “brakes.”

Metacognition

The ability to reflect on your own thoughts and mental strategies. It’s why adolescents become more capable of noticing “wait, I’m overreacting,” questioning assumptions, and thinking through how they learn or why they made a decision.

Dopamine system changes

During adolescence, the dopamine (reward) system becomes more sensitive and reactive, especially to things that feel rewarding right now.

What that looks like:

• Rewards feel bigger: exciting, novel, or “fun” experiences can feel extra motivating.

• Social reward matters more: approval from friends, fitting in, getting attention can hit like a stronger reward.

• More novelty/sensation seeking: teens are more likely to chase new experiences because the “reward signal” is stronger.

• Risk goes up in certain situations: when a reward is immediate (or peers are watching), the dopamine system can push the “go” signal harder than the brain’s control system can slow it down.

Prefrontal cortex (PFC)

The PFC supports planning, reasoning, and self-control. It develops gradually, and because it’s still maturing during adolescence, decision-making can be inconsistent—especially when emotions, stress, or peer pressure are present.

Impulsivity

Acting quickly without fully thinking through consequences. Impulsivity tends to show up more strongly when emotions are high or when there’s a reward right in front of you, because “in-the-moment” systems overpower long-term planning.

Sensation seeking

The drive to pursue exciting, intense, or novel experiences. It can rise in adolescence and push risk-taking even when someone understands the risks, because the reward of the experience feels unusually appealing

• The reward system gets extra reactive (dopamine): rewards and novelty feel stronger, so your brain gives a bigger “that was worth it” signal when something is exciting. That makes you more motivated to chase new experiences.

• Your control system is still catching up (PFC): the prefrontal cortex—the part that helps you pause, plan, and think long-term—is still developing. So the “go for it” feeling can be louder than the “wait, think” voice, especially in the moment.

Brain-development “mismatch” and risk-taking

A common explanation is that reward/emotion systems become highly reactive earlier, while the control systems that regulate behavior mature more slowly. That gap increases risk-taking potential, especially in social settings where the “reward” is status, belonging, or approval.

WHO IS Casey (Casey et al.)

A major researcher in adolescent brain development. Casey’s work is commonly used to explain adolescent risk-taking through brain development timing—especially the idea that control systems and reward systems don’t mature on the same schedule.

Renegotiation of parent relationships

The process where parents and adolescents rework their relationship as the teen becomes more independent. Teens push for more autonomy and privacy, and parents shift from direct control to more guidance and trust-based rules. It often involves more arguing or boundary-testing at first, but the goal is a new balance where the teen has more freedom while still being supported and monitored.

Distal monitoring

Parents still keep track of what’s going on, but from more of a distance. Instead of constant direct supervision, it’s more about check-ins, expectations, and knowing a teen’s routines and social world while allowing autonomy.

Psychological control

A parenting style that tries to control a teen’s internal world—feelings, thoughts, or identity instead of just setting rules—often through guilt, pressure, or manipulation. This can interfere with healthy autonomy because it doesn’t just guide behavior; it pushes the teen to think/feel a certain way.

Peer relationship changes

Peer interactions become more emotionally meaningful and identity-relevant. Adolescents often share deeper thoughts/feelings, form more mixed-sex groups, and cluster into groups that feel similar (interests, style, values), which shapes social identity and norms.

Riskier behavior in groups

Teens often take more risks in groups because social rewards become part of the payoff. Approval, laughter, status, or not wanting to look “scared” can make risky choices feel worth it in the moment.

Crowds

Crowds are large, reputation-based peer groups in adolescence—like social categories people get placed into (or choose), based on image, interests, and status.

Examples: “jocks,” “popular kids,” “band kids,” “skaters,” “theater kids,” “gamers,” etc.

Why they matter:

• they shape who you hang out with (even beyond close friends)

• they influence norms (what’s “cool,” what you’re “supposed” to wear/do)

• they affect status and identity, because being labeled in a crowd can change how others treat you and how you see yourself

Romantic relationships (in adolescence)

Romantic relationships often begin in adolescence and can be short-lived but still psychologically important. They help teens learn intimacy, boundaries, and identity in relationships, and they can strongly affect mood and self-concept.

Identity

A developing sense of who you are—your values, goals, beliefs, and roles. Adolescence is a major identity period because teens gain more independence and begin making choices that shape their future direction. Identity development usually involves trying things out, reflecting, and then settling into commitments.

• Prefrontal cortex (PFC) is still maturing
  This is the part that helps with planning, self-control, and putting your life into a coherent story. As it develops, you get better at long-term thinking (“what kind of person do I want to be?”) and making choices based on values instead of just the moment.

• Self-focused brain networks get stronger
  Areas like the medial prefrontal cortex (a key “self-reflection” region) and the default mode network get more active/organized. That supports things like introspection, comparing yourself to others, and thinking about your past + future as one continuous “me.”

Exploration

The process of actively considering different possibilities for who you could be. That could mean trying different interests, beliefs, friend groups, goals, or values—basically “testing” options rather than accepting one path automatically.

Commitment

Choosing a direction and sticking with it—like committing to certain values, goals, relationships, career interests, or identity-based beliefs. Commitment usually becomes stronger when it follows real exploration rather than being rushed or imposed.

Marcia’s identity statuses

A framework that describes where someone is in identity development based on two dimensions: whether they’ve had a meaningful period of exploration (“crisis”) and whether they’ve made commitments. It’s useful because it explains why two teens can look very different even if they’re the same age.

Marcia’s identity statuses are a way to describe where someone is in identity development using two questions:

1. Have they explored different options seriously? (this is the “crisis” part)

2. Have they made a commitment to a direction (values, goals, beliefs, career path, etc.)?

Identity achievement

High exploration and high commitment. The person has seriously considered alternatives and then made choices they personally identify with, which usually leads to a more stable and confident sense of self.

You’ve looked at real options and then chosen what fits you.

• Example: you considered different majors/careers and committed to one because it matches your interests/values

Foreclosure

Low exploration and high commitment. The person commits without really questioning or exploring—often adopting beliefs or paths that were chosen by family, culture, or authority figures. It can look “stable,” but it may be fragile if the person later confronts new experiences.

Foreclosure (exploration ❌ + commitment ✅)
You committed without really exploring—often adopting what parents, culture, or authority expects.

• Example: “I’m going to be a doctor because my family expects it,” without considering other paths.

Moratorium

High exploration and low commitment. The person is actively searching, questioning, and trying things out, but hasn’t settled on a direction yet. This can feel stressful, but it’s often a normal and productive stage of identity growth.

Moratorium (exploration ✅ + commitment ❌)
You’re actively searching, questioning, trying things out, but you haven’t decided yet.

• Example: switching interests, experimenting with styles/friend groups, unsure about future plans but seriously thinking.

Identity diffusion

Low exploration and low commitment. The person isn’t deeply exploring options and also isn’t committing to a direction, which can look like drifting, avoidance, or feeling disconnected from future goals.

identity Diffusion (exploration ❌ + commitment ❌)
No strong searching and no real commitments—more drifting, avoiding, or feeling disconnected from future goals.

• Example: “I don’t know and I’m not really trying to figure it out.”

WHO IS James Marcia

A developmental psychologist known for expanding identity development into four “statuses” (achievement, foreclosure, moratorium, diffusion). His model helps explain identity as a process, not a single event.

Ethnic/Racial Identity (ERI)

A central part of self-concept tied to ethnic/racial belonging, meaning, and personal connection to a group. ERI develops through exploration (learning, reflecting, engaging) and commitment (feeling secure and affirmed). It’s linked to well-being, self-esteem, and academic outcomes partly because it can provide belonging and meaning.

ERI as a buffer

A strong ERI can protect mental health by reducing how damaging discrimination-related stress becomes. When someone has a secure sense of belonging and meaning, identity-based attacks may feel less destabilizing, and coping resources may be stronger.

Microaggressions

Subtle, everyday slights or invalidations aimed at someone’s identity. Even when individual moments seem “small,” repeated experiences can accumulate into chronic stress and affect mood, sleep, and feelings of safety or belonging.

WHO IS Jean Phinney

A researcher known for foundational work on ethnic identity development. A key idea associated with this work is that ethnic/racial identity involves both exploration and commitment as part of self-concept

WHO IS Dr. Yip

A researcher highlighted for work connecting ERI to daily well-being and showing how ERI can protect against stress related to discrimination. This work also connects identity-related stress to outcomes like sleep and mental health.

Emerging adulthood

A proposed stage roughly from ages 18–25 where people often feel “in between” adolescence and adulthood. It’s typically marked by exploration in love, work, and identity, along with instability (moves, school changes, job shifts). It’s not universal—access depends on culture, economic resources, and expectations.

Five features of emerging adulthood

Identity exploration, instability, self-focus, feeling in-between, and possibilities. Together these describe why this period can feel both exciting and uncertain—lots of freedom, but also less structure.

WHO IS J. J. Arnett

A developmental psychologist best known for proposing “emerging adulthood” and describing the major features that define the 18–25 period in many industrialized settings.

Why sleep matters in adolescence

Sleep supports cognitive functioning (attention, memory), emotional regulation, and decision-making. When sleep is low, it’s harder to focus and control impulses, and emotions can become more reactive. So sleep affects both school performance and mental health risk.

Adolescent sleep needs

Adolescents generally need about 8–10 hours of sleep per night. Many get less partly because circadian rhythms shift later (their body wants to sleep and wake later), and screens/technology can also interfere with sleep routines and quality.

Effects of sleep deprivation

Too little sleep is linked to weaker memory, reduced attention, and worse impulse control. Over time it also increases risk for mood problems and can contribute to higher risk-taking behavior, partly because self-regulation gets harder when the brain is tired.

Sleep disparities

Some adolescents—especially ethnic minority adolescents—experience more sleep disruption due to chronic stressors like discrimination and family responsibilities. Sleep can also help explain (mediate) how discrimination connects to mental health outcomes.

WHO IS Ann Masten

A major resilience researcher known for defining resilience as positive adaptation despite adversity and emphasizing that resilience is influenced by systems around the person, not just personality.

WHO IS Carol Dweck

A psychologist known for the growth mindset concept—the idea that abilities can improve through effort, strategies, and learning. Growth mindset supports resilience because setbacks feel like information for improvement rather than proof of failure.