Developed structuralism; focused on the basic elements of consciousness using introspection.

Developed functionalism; studied the purpose of behavior and mental processes.

Championed the behavioral perspective, focusing on observable behavior.

A key figure in behaviorism; emphasized how behavior is shaped by rewards and punishments (operant conditioning).

Founded the psychodynamic perspective; emphasized the unconscious mind, childhood conflicts, and psychoanalysis.

Central figures in the humanistic perspective; emphasized free will, self-actualization, and personal growth.

Discovered classical conditioning through his work with dogs’ salivation reflexes.

Conducted the “Little Albert” experiment, demonstrating how fear can be classically conditioned in humans.

Pioneered the study of operant conditioning; used the Skinner box to show how behavior is influenced by consequences.

Discovered taste aversion, showing biological constraints on learning.

Known for observational learning and the classic Bobo doll experiment.

Proposed the hierarchy of needs, culminating in self-actualization.

Proposed the James-Lange theory of emotion, which states that emotions result from our physiological reactions to events.

Proposed the Cannon-Bard theory of emotion, which states that physiological arousal and emotional experience occur simultaneously.

Proposed the Schachter-Singer (two-factor) theory of emotion, which states that emotion is determined by physiological arousal and a cognitive label for that arousal.

Studied imprinting in animals, highlighting critical periods in development.

Studied attachment in infant monkeys, demonstrating the importance of contact comfort over nourishment.

Developed the “Strange Situation” to study different styles of infant attachment (secure, avoidant, etc.).

Identified key parenting styles (authoritarian, authoritative, permissive, uninvolved).

Proposed a theory of psychosocial development across eight stages from infancy to old age.

Proposed a seminal theory of cognitive development in four stages (sensorimotor, preoperational, concrete operational, formal operational).

Proposed a theory of moral development with three levels (preconventional, conventional, postconventional).

Proposed a stage model for coping with death and dying (denial, anger, bargaining, depression, acceptance).

Proposed psychoanalytic theory of personality, featuring the id, ego, superego, and defense mechanisms.

A trait theorist who categorized traits into cardinal, central, and secondary.

Used factor analysis to identify 16 core personality traits.

Proposed a trait theory based on three major dimensions: extroversion, neuroticism, and psychoticism.

A humanistic theorist who emphasized the self-concept, unconditional positive regard, and the path to self-actualization.

Proposed the General Adaptation Syndrome (GAS) model, describing the body’s three-stage response to stress (alarm, resistance, exhaustion).

Researched learned helplessness, a state where people believe they have no control over aversive events.

Developed psychoanalysis, using techniques like free association and dream interpretation.

Developed Rational-Emotive Behavior Therapy (REBT), which focuses on challenging and changing irrational beliefs.

Developed cognitive therapy for depression, focusing on identifying and changing distorted thinking patterns.

Developed person-centered (or client-centered) therapy, based on providing unconditional positive regard.

Known for his classic experiments on conformity to group pressure.

Known for his controversial experiments on obedience to authority.

Researched the bystander effect and diffusion of responsibility in emergency situations.