Explore major psychological theories, schools of thought, famous psychologists, classic experiments, developmental ideas, memory, learning, personality, motivation, social behaviour and the modern neuroscience era.
Psychologists study topics such as perception, learning, memory, emotion, motivation, personality, development, social interaction, mental health and the relationship between brain and behaviour.
Psychology does not have one single theory that explains everything. Different theories emphasize different levels of explanation — biological, cognitive, behavioural, developmental, social, cultural and psychological.
Wundt established a laboratory in Leipzig commonly regarded as a major milestone in the emergence of psychology as an independent experimental discipline.
William James and other thinkers focused on what mental processes and behaviour do — their functions and adaptive significance.
Sigmund Freud developed a theory emphasizing unconscious processes, conflict, development and personality.
Researchers such as John B. Watson and B. F. Skinner emphasized observable behaviour and learning through environmental contingencies.
Gestalt psychologists emphasized organized patterns of perception and the idea that the whole cannot always be understood simply by adding its individual parts.
Psychology increasingly returned to scientific study of internal processes such as memory, attention, language and problem solving.
Humanistic psychologists emphasized subjective experience, personal growth, meaning and human potential.
Psychology increasingly integrates brain imaging, neuroscience, computational modelling, genetics and behavioural science.
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Structuralism attempted to study the basic components of conscious experience using introspective methods.
Participants reported aspects of their immediate conscious experience under controlled conditions.
Focused on the functions and adaptive value of mental processes and behaviour rather than only their structure.
Functionalists used observations, introspection and comparative evidence to study how consciousness helps organisms adapt.
Freud proposed that unconscious processes, conflicts and early experiences play important roles in personality and behaviour.
Free association and analysis of dreams were used clinically to explore unconscious material.
Behaviorism emphasized observable behaviour and environmental learning rather than introspection as the primary subject of psychology.
Watson and Rosalie Rayner paired a loud noise with a white rat and reported conditioned fear responses in an infant.
Classical conditioning describes learning in which a previously neutral stimulus becomes associated with a stimulus that naturally produces a response.
Pavlov repeatedly paired a neutral stimulus such as a metronome or bell with food. Eventually the conditioned stimulus could produce salivation.
Behaviour can be strengthened or weakened by its consequences.
Rats or pigeons could perform an action such as pressing a lever or pecking a key to obtain a consequence such as food.
Key concepts: reinforcement, punishment, shaping and schedules of reinforcement.
People can learn behaviours by observing models, not only through direct reinforcement.
Children observed adult models behaving aggressively toward a Bobo doll. Their subsequent behaviour was studied for imitation of the model.
Gestalt psychology emphasizes organized patterns in perception.
Rapidly presented stationary lights could be perceived as apparent motion, demonstrating that perception is not simply a collection of independent sensations.
Köhler argued that some problem solving can occur through sudden reorganization of the problem rather than gradual trial and error.
Chimpanzees were observed solving problems involving objects such as boxes and sticks to reach food.
Piaget proposed stages of cognitive development in childhood.
Children were shown equivalent quantities presented in different shapes or containers. Younger children often judged the transformed display as having more or less, suggesting differences in developing reasoning.
Stages: sensorimotor → preoperational → concrete operational → formal operational.
Cognitive development is strongly influenced by social interaction, language and cultural tools.
The Zone of Proximal Development describes tasks a learner can perform with appropriate assistance but cannot yet perform independently.
Attachment theory proposes that early relationships with caregivers play an important role in emotional and social development.
Bowlby's theory drew on clinical observations, developmental research, ethology and studies of separation and caregiving.
Ainsworth developed the Strange Situation procedure to study individual differences in infant attachment behaviour.
Infants experienced brief separations and reunions with a caregiver in a structured laboratory setting. Their responses helped researchers identify attachment patterns.
Maslow emphasized human motivation, psychological needs, growth and self-actualization.
Maslow's hierarchy was developed from theoretical and biographical analysis rather than a single controlled experiment.
Common representation: physiological → safety → belonging → esteem → self-actualization.
Rogers developed person-centred therapy, emphasizing empathy, genuineness and unconditional positive regard.
Therapeutic interactions and client reports were used to study conditions associated with psychological growth.
Human cognition can be studied as a system involving processes such as attention, encoding, storage and retrieval.
Researchers compared recall under different conditions to understand how information is encoded and retrieved.
A classic model proposed sensory memory, short-term memory and long-term memory as interacting components of information processing.
Research using recall and recognition tasks helped distinguish temporary and more durable memory processes.
Working memory describes the limited-capacity system used to temporarily hold and manipulate information.
People performing different simultaneous memory tasks showed patterns suggesting multiple interacting components rather than one simple store.
Ebbinghaus systematically studied memory and forgetting using himself as a participant.
He memorized lists of unfamiliar syllables and measured learning and retention over time, producing the famous forgetting curve.
People often remember items at the beginning and end of a list better than items in the middle.
Participants recalled words from lists. Recall patterns showed primacy and recency effects.
Milgram investigated obedience to authority.
Participants were instructed by an experimenter to administer what they believed were increasingly strong electric shocks to another person. The shocks were simulated.
Asch studied whether people would conform to an obviously incorrect group judgment.
Participants compared line lengths while confederates deliberately gave incorrect answers. Some participants conformed to the group.
The Stanford Prison Experiment investigated behaviour in an artificial prison setting.
Students were assigned roles as prisoners or guards. The study was ended early after concerning behaviour emerged.
Self-efficacy refers to a person's belief in their ability to successfully perform a particular task.
Bandura studied how modelling and mastery experiences could influence expectations of personal capability and subsequent behaviour.
Cognitive dissonance theory proposes that inconsistency between beliefs, attitudes and behaviour can create psychological discomfort and motivate change.
Participants performed a boring task and were asked to tell another person it was interesting. Those paid a small amount sometimes showed greater attitude change than those paid more, interpreted as evidence for dissonance under particular conditions.
People try to explain behaviour by attributing it to internal factors such as personality or external factors such as situations.
Participants evaluated writers after reading essays that supported or opposed particular political positions under conditions where the writer's freedom of choice was manipulated.
Memory can be influenced by information encountered after an event.
Participants viewed events and later received differently worded questions or misleading information. Their later memories could be altered in some conditions.
Attention determines which information receives deeper processing.
Participants heard different messages in different ears and were asked to attend to one stream, demonstrating limits and selectivity in attention.
Broadbent proposed an early-selection model of attention in which information is filtered before more complete processing.
Participants repeated an attended message while ignoring another message presented simultaneously.
Research suggests sleep can influence memory consolidation and learning.
Researchers compare memory performance after periods of sleep and wakefulness following learning tasks.
Spearman proposed a general intelligence factor, often called g, to explain positive correlations among different mental abilities.
Statistical relationships among different cognitive tests were analysed to identify underlying common factors.
Gardner proposed a theory of multiple intelligences, including linguistic, logical-mathematical, spatial, bodily-kinesthetic, musical, interpersonal, intrapersonal and naturalistic abilities.
Personality research commonly describes five broad dimensions: Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism.
Researchers analysed patterns among personality descriptions and questionnaire items to identify recurring dimensions.
Allport emphasized individual traits as important units for understanding personality.
He studied personality descriptions and proposed categories such as cardinal, central and secondary traits.
Freud proposed stages of personality development associated with different bodily zones and psychological conflicts.
Oral → Anal → Phallic → Latency → Genital
Kohlberg proposed stages of moral reasoning based on increasingly complex principles of justice and social expectations.
Participants responded to hypothetical dilemmas such as the famous Heinz dilemma. Kohlberg analysed the reasoning used rather than simply whether the participant chose one action or another.
Erikson proposed eight psychosocial stages extending across the lifespan. Each stage involves a central developmental challenge.
The theory was developed from clinical work, developmental observation and psychoanalytic thinking rather than one single laboratory experiment.
Piaget studied children's understanding of rules, intentions and consequences.
Children were asked about rules in games and stories involving accidents or intentional wrongdoing.
Clark Hull proposed that biological needs create drives that motivate behaviour aimed at restoring physiological balance.
Animal learning experiments examined how deprivation and reinforcement affected behaviour.
Deci and Ryan proposed that autonomy, competence and relatedness are important psychological needs.
Experiments compared different reward and choice conditions to study effects on intrinsic motivation.
Behaviour and mental processes are studied in relation to the brain, nervous system, hormones, genetics and physiology.
Methods include lesion studies, electrophysiology, neuroimaging, psychophysiological measurements and genetic research.
Hebb proposed influential ideas about how repeated neural activity could contribute to learning and memory.
His ideas helped connect psychological learning theories with neural mechanisms.
Research on patients whose corpus callosum had been severed provided evidence about specialization and communication between cerebral hemispheres.
Information presented to one visual field could sometimes produce different reporting or response patterns depending on which hemisphere received the information.
Expectations and treatment context can influence reported symptoms and some physiological responses.
Participants receiving an inactive treatment can sometimes report improvement, allowing researchers to distinguish treatment effects from expectancy and other factors.
Martin Seligman and colleagues studied how exposure to uncontrollable aversive events could affect later behaviour.
Animals exposed to uncontrollable events sometimes later showed reduced attempts to escape when escape became possible.
Positive psychology studies well-being, strengths, meaning, positive emotion and human flourishing.
Researchers test exercises such as gratitude or identifying positive experiences and measure changes in well-being.
This perspective examines whether some psychological mechanisms may reflect adaptations shaped by natural selection.
Researchers compare behavioural patterns across populations and investigate whether some preferences or responses are widespread.
Culture can influence perception, cognition, emotion, identity, development and social behaviour.
Researchers compare people from different cultural settings using common psychological tasks and questionnaires.
A quick revision table.
| Psychologist(s) | Study / Experiment | Main concept |
|---|---|---|
| Ivan Pavlov | Dogs & salivation | Classical conditioning |
| John Watson & Rosalie Rayner | Little Albert | Conditioned emotional response |
| B. F. Skinner | Skinner Box | Operant conditioning |
| Albert Bandura | Bobo Doll | Observational learning |
| Max Wertheimer | Phi phenomenon | Gestalt perception |
| Wolfgang Köhler | Chimpanzee insight studies | Insight learning |
| Solomon Asch | Line judgment | Conformity |
| Stanley Milgram | Obedience experiment | Obedience to authority |
| Philip Zimbardo | Stanford Prison Experiment | Roles & social behaviour |
| Leon Festinger | Forced-compliance study | Cognitive dissonance |
| Elizabeth Loftus | Misinformation studies | Memory reconstruction |
| Hermann Ebbinghaus | Nonsense syllables | Forgetting & memory |
| Mary Ainsworth | Strange Situation | Attachment |
| Jean Piaget | Conservation tasks | Cognitive development |
| Lawrence Kohlberg | Moral dilemmas | Moral reasoning |
| Roger Sperry | Split-brain studies | Brain lateralization |
| Martin Seligman | Learned helplessness research | Learning & control |
Converting information into a form that can be stored.
Maintaining information over time.
Accessing stored information.
Temporarily holding and manipulating information during cognitive tasks.
Memory system capable of retaining information for extended periods.
Memory for skills and procedures, such as riding a bicycle.
Memory for facts and general knowledge.
Memory for personally experienced events.
| Theory | Associated psychologist | Core idea |
|---|---|---|
| Classical Conditioning | Ivan Pavlov | Association between stimuli |
| Operant Conditioning | B. F. Skinner | Consequences influence behaviour |
| Social Learning | Albert Bandura | Learning through observation and modelling |
| Insight Learning | Wolfgang Köhler | Problem solving through restructuring |
| Cognitive Learning | Edward Tolman and others | Internal representations can guide learning |
| Constructivism | Piaget / Vygotsky | Learners actively construct knowledge |
Personality influenced by unconscious processes, conflicts and development.
Personality can be described using relatively stable dimensions or traits.
Emphasizes self-concept, growth, choice and personal meaning.
Personality emerges from interaction among behaviour, cognition and environment.
Personality differences may partly relate to genetics, brain systems and temperament.
Changing behaviour or judgments to align with group influence.
Following instructions from an authority figure.
A tendency toward poor decision-making when group cohesion discourages critical evaluation.
Presence of others can influence performance, depending on the task and circumstances.
How people explain the causes of behaviour.
Discomfort associated with inconsistency between beliefs, attitudes and behaviour.
Attitudes or evaluations directed toward people based on group membership.
Actions intended to benefit or help others.
Explores emotional patterns, relationships and psychological processes, including unconscious influences.
Uses principles of learning to modify problematic behaviours.
Focuses on identifying and modifying unhelpful patterns of thinking.
Cognitive Behaviour Therapy combines cognitive and behavioural techniques and is widely used for many psychological problems.
Emphasizes the therapeutic relationship, personal experience and growth.
Studies psychological conditions in relation to brain systems, genetics, physiology and medication where appropriate.
Specialized cells that communicate through electrical and chemical signalling.
Junction where information is transmitted between neurons or between a neuron and another cell.
Chemical messengers involved in communication within the nervous system.
Brain region involved in executive functions such as planning, control and decision-making.
Part of a network involved in emotional processing, learning and threat-related responses.
Important for memory formation and spatial processing.
Helps regulate homeostasis, endocrine functions and motivated behaviours.
Large fibre bundle connecting the two cerebral hemispheres.
Modern psychology is increasingly connected with neuroscience, artificial intelligence, computational modelling and large-scale behavioural data.
Uses mathematical and computational models to explain cognitive processes.
AI provides new tools for studying language, learning, perception and decision-making.
Researchers investigate how genetic variation interacts with environments and development.
fMRI, EEG and other techniques help investigate relationships between brain activity and behaviour.
Large datasets allow researchers to examine behaviour across populations and contexts.
Future approaches may increasingly combine individual differences, biology, behaviour and environment.
Psychology is increasingly important for understanding how people interact with AI systems.
Privacy, bias, autonomy, manipulation, mental well-being and responsible AI use are important psychological questions.
| Psychologist | Remember for |
|---|---|
| Wilhelm Wundt | Early experimental psychology / laboratory |
| William James | Functionalism |
| Sigmund Freud | Psychoanalysis |
| Ivan Pavlov | Classical conditioning |
| John B. Watson | Behaviorism |
| B. F. Skinner | Operant conditioning |
| Albert Bandura | Observational learning / self-efficacy |
| Max Wertheimer | Gestalt psychology |
| Wolfgang Köhler | Insight learning |
| Jean Piaget | Cognitive development |
| Lev Vygotsky | Sociocultural development |
| John Bowlby | Attachment theory |
| Mary Ainsworth | Strange Situation |
| Abraham Maslow | Hierarchy of needs |
| Carl Rogers | Person-centred approach |
| Solomon Asch | Conformity |
| Stanley Milgram | Obedience |
| Leon Festinger | Cognitive dissonance |
| Elizabeth Loftus | Memory misinformation |
| Hermann Ebbinghaus | Forgetting and memory |
| Roger Sperry | Split-brain research |
| Martin Seligman | Learned helplessness / positive psychology |
Classic psychology experiments are historically important, but they should not automatically be treated as unquestionable facts. Some famous studies have been criticized for small or unrepresentative samples, methodological problems, replication issues, demand characteristics, cultural limitations or ethical concerns.
Psychology has developed substantially since many of these studies were conducted. Modern research generally places much greater emphasis on informed consent, participant protection, preregistration, statistical rigour, replication and transparent reporting.