Physical, Cognitive, and Psychosocial Development in Adolescence and Emerging Adulthood

Physical and Cognitive Development in Adolescence

Puberty

Puberty is the developmental period when a child's body matures physically and becomes capable of reproduction.

• Typical Onset: Begins between ages 8–13 in girls and 9–14 in boys.

• Gender Differences: Girls usually start and complete puberty earlier than boys, experiencing their growth spurt first. Boys tend to have a larger overall growth spurt and gain more muscle mass.

Menarche and Spermarche

• Menarche: The first menstrual period in girls, marking reproductive maturity.

• Spermarche: The first ejaculation in boys, indicating the start of sperm production.

Hormonal Chain of Events in Puberty

• The hypothalamus releases GnRH (gonadotropin-releasing hormone).

• The pituitary gland releases LH (luteinizing hormone) and FSH (follicle-stimulating hormone).

• The gonads (ovaries or testes) produce sex hormones (estrogen, testosterone).

• These hormones drive physical changes: growth spurts, body hair, reproductive organ development, and sexual maturity.

Brain Development and Cognitive Control

• The prefrontal cortex (responsible for decision-making, planning, and impulse control) is not fully developed in adolescence.

• This underdevelopment contributes to impulsive and risky behaviors in teenagers.

Circadian Rhythm and Sleep

• Circadian rhythm: The body's internal 24-hour clock regulating sleep and wake cycles.

• During adolescence, the sleep cycle shifts later, making teens want to stay up and wake up later.

• This shift can cause difficulty with early school start times.

Impact of Stress on Puberty

• Chronic stress can alter hormone levels, affecting the timing and progression of puberty.

• Stress is also linked to anxiety, depression, sleep problems, and unhealthy behaviors.

Increased Endurance in Adolescence

• Improvements in the cardiovascular and respiratory systems increase endurance.

• Muscles become stronger, and the body delivers oxygen more efficiently, allowing for longer physical activity.

Eating Disorders

Eating disorders are serious mental health conditions involving unhealthy eating behaviors and preoccupations with food, weight, or body image.

Eating Disorder	Description
Anorexia nervosa	Restricting food intake due to intense fear of gaining weight.
Bulimia nervosa	Binge eating followed by compensatory behaviors (vomiting, fasting, excessive exercise).
Binge-eating disorder	Eating large amounts of food with a sense of loss of control, without regular compensatory behaviors.

• Most common onset: adolescence or young adulthood.

• Females are more frequently diagnosed, but all genders and body types can be affected.

Primary vs. Secondary Sex Characteristics

Primary Sex Characteristics	Secondary Sex Characteristics
Directly involved in reproduction (ovaries, testes, uterus, penis, vagina)	Physical changes not directly involved in reproduction (breast development, facial hair, deeper voice, pubic hair, wider hips)

Adolescent Egocentrism

• Adolescent egocentrism: Heightened self-focus and belief that others are highly attentive to one's behavior and appearance.

• Personal fable: Belief in the uniqueness of one's experiences.

• Invincibility fable: Belief that negative outcomes will not happen to oneself.

• Imaginary audience: Belief that others are constantly watching and judging.

Piaget's Formal Operational Stage

• Begins around age 11 and continues into adulthood.

• Characterized by abstract thinking, logical reasoning, and the ability to consider hypothetical situations.

Reasoning: Top-Down vs. Bottom-Up

Top-Down Reasoning	Bottom-Up Reasoning
Deductive; general rule to specific case	Inductive; specific observations to general conclusion
"All humans need oxygen. I am human. Therefore, I need oxygen."	"I observe people need oxygen, so I conclude humans need oxygen."

Dual Processing: Analytic vs. Intuitive Thought

• Analytic thought: Logical, careful, and deliberate decision-making.

• Intuitive thought: Fast, automatic, emotional, and based on experience.

• Adolescents may rely more on intuitive thought, especially under emotional or peer influence.

Education Levels

Level	Meaning
Primary	Elementary/early schooling
Secondary	Middle and high school
Tertiary	Post-secondary (college, university, vocational school)

Developmental Regression in Middle School

• Temporary decline in academic performance, motivation, or behavior during the transition to middle school.

• Caused by increased academic difficulty, new social environments, puberty, and greater responsibility.

Psychosocial Development in Adolescence

Identity Formation

• The main psychosocial task is developing a sense of identity: understanding who you are, your values, and your place in society.

Erikson's Stage: Identity vs. Role Confusion

• Identity: A clear sense of self and direction.

• Role confusion: Uncertainty about self, values, and future roles.

Marcia's Four Identity Statuses

Stage	Exploration	Commitment	Example
Identity diffusion	No	No	No career idea, not exploring
Identity foreclosure	No	Yes	Chooses career due to parental expectation
Identity moratorium	Yes	No	Exploring options, not yet decided
Identity achievement	Yes	Yes	Explored and decided on a career

Areas of Identity Formation

• Vocational, religious/spiritual, political, gender, ethnic/cultural, and sexual identity.

Sex vs. Gender

Sex	Gender
Biological characteristics (chromosomes, organs, hormones)	Social and personal identity (roles, expression, identity)

Gender Dysphoria (DSM-5-TR)

• Gender Dysphoria: Distress due to a mismatch between experienced gender and sex assigned at birth.

• Being transgender is not a mental disorder; the diagnosis focuses on distress, not identity.

Familism

• Belief in the importance of family support, respect, and responsibility.

Parental Monitoring and Healthy Interaction

• Parental monitoring involves knowing a teen's activities, friends, and whereabouts, ideally through communication and trust.

• Healthy relationships balance independence with guidance, open communication, and emotional support.

Sexual Orientation

• Pattern of romantic, emotional, or sexual attraction (heterosexual, homosexual, bisexual, asexual, etc.).

• Sexual orientation is distinct from gender identity.

Sex Education

• Abstinence-only education may leave students uninformed about contraception and STI prevention, increasing risks.

• Effective sex education includes information on reproductive health, contraception, STI prevention, consent, and healthy relationships.

Delinquency and Risk Factors

• Delinquency: Law- or rule-breaking behaviors by minors.

• Risk factors: Poor supervision, family conflict, peer pressure, substance use, poverty, poor school performance, abuse, impulsivity.

Suicidal Ideation

• Thinking about suicide; risk factors include depression, anxiety, bullying, isolation, family conflict, substance use, prior attempts.

• Warning signs: Talking about death, hopelessness, withdrawal, giving away belongings.

Offender Types: Life-Course vs. Adolescent-Limited

Life-Course-Persistent	Adolescence-Limited
Antisocial behavior starts early and continues into adulthood	Delinquency begins in adolescence and usually ends in adulthood
Linked to early risk factors	Linked to peer pressure and desire for independence

Marijuana Use in Adolescence

• Can impair memory, concentration, motivation, decision-making, and learning.

• Increases risk of dependence and mental health problems, especially with frequent use.

Physical and Cognitive Development in Emerging Adulthood

Postformal Thought

• A proposed stage beyond Piaget's formal operations, involving practical, flexible, and dialectical thinking.

• Recognizes multiple perspectives and that not all problems have one solution.

Emerging Adulthood

• Spans approximately ages 18–25 (sometimes later).

• Characterized by exploration of independence, careers, relationships, and identity.

Common Life Events

• Attending higher education, starting a career, moving out, financial independence, dating, exploring beliefs, and making long-term plans.

Peak Physical Strength

• Physical strength and endurance peak in the twenties or early thirties, then gradually decline.

WEIRD Populations in Research

• WEIRD: Western, Educated, Industrialized, Rich, Democratic.

• Much psychological research is based on WEIRD populations, which may not represent global diversity.

Contraception and Sexually Transmitted Infections (STIs)

Method	Description
Condoms	Prevent pregnancy and reduce STI risk
Birth control pills	Hormonal prevention of pregnancy
IUD	Device in uterus to prevent pregnancy
Implant	Hormonal device under the skin
Abstinence	Avoiding sexual activity

• Common STIs: Chlamydia, gonorrhea, syphilis, HPV, herpes, HIV.

• Many STIs are asymptomatic; condoms reduce but do not eliminate risk; testing is important.

Allostasis and Allostatic Load

• Allostasis: The body's process of achieving stability through physiological or behavioral change in response to stress.

• Allostatic load: The cumulative wear and tear on the body from chronic stress.

Substance Use Disorder (SUD)

• Continued use of a substance despite negative consequences, with features such as cravings, tolerance, withdrawal, and loss of control.

Stereotype Threat

• Performance anxiety caused by fear of confirming negative stereotypes about one's group.

Vocational Identity

• Understanding one's career interests, abilities, and goals; often explored through education, work experience, and self-reflection in emerging adulthood.

Personality Influences

• Personality is shaped by genetics, environment, life experiences, social interactions, and personal choices.

Erikson's Stage: Intimacy vs. Isolation

• Main task is forming close, meaningful relationships (intimacy) versus experiencing loneliness or isolation.

Friendships and Intimacy in Emerging Adulthood

• Friendships become deeper, with emphasis on trust, loyalty, and emotional support.

• Factors in romantic relationships include emotional maturity, communication, trust, commitment, shared values, and conflict resolution.