Dictionary of Theories
A growing reference guide to the key theories that help us understand human behaviour, society and the mind.
Psychology and the social sciences have given us powerful frameworks for making sense of why people think, feel and act the way they do. This dictionary introduces some of the most influential theories across psychology, sociology and organisational behaviour — explained clearly, without unnecessary jargon.
This is a living resource. New theories will be added regularly. A comprehensive, fully referenced edition is also coming soon as a standalone guide.
Attachment Theory
John Bowlby (1969)
Attachment theory proposes that humans are biologically predisposed to form close emotional bonds with caregivers from birth. These early attachment relationships — whether secure, anxious or avoidant — shape how individuals relate to others throughout their lives, influencing everything from romantic relationships to how they respond to stress.
Bowlby, J. (1969). Attachment and loss: Vol. 1. Attachment. Basic Books.
Cognitive Dissonance Theory
Leon Festinger (1957)
Cognitive dissonance describes the psychological discomfort people experience when they hold two conflicting beliefs, or when their actions contradict their values. To reduce this discomfort, people tend to change one of their beliefs, add new justifications, or minimise the importance of the conflict. This theory helps explain why people often rationalise decisions after making them rather than before.
Festinger, L. (1957). A theory of cognitive dissonance. Stanford University Press.
Social Learning Theory
Albert Bandura (1977)
Bandura proposed that people learn not only through direct experience but by observing others. Behaviour is influenced by what we see modelled around us — by parents, peers, media and cultural figures. Crucially, Bandura also introduced the concept of self-efficacy: the belief in one’s own ability to succeed, which significantly shapes motivation and persistence.
Bandura, A. (1977). Social learning theory. Prentice Hall.
Maslow’s Hierarchy of Needs
Abraham Maslow (1943)
Maslow proposed that human motivation operates in a hierarchy — from basic physiological needs such as food and shelter, through safety, belonging and esteem, to self-actualisation at the peak. While the strict hierarchical model has been debated, the framework remains widely used in psychology, education and organisational behaviour as a way of understanding what drives human motivation at different levels.
Maslow, A. H. (1943). A theory of human motivation. Psychological Review, 50(4), 370–396.
Erikson’s Stages of Psychosocial Development
Erik Erikson (1950)
Erikson proposed that human development unfolds across eight stages throughout the lifespan, each presenting a psychological conflict that must be navigated. From trust versus mistrust in infancy to integrity versus despair in old age, each stage shapes identity, relationships and psychological wellbeing. Unlike Freud, Erikson emphasised that development continues well into adulthood.
Erikson, E. H. (1950). Childhood and society. Norton.
Self-Determination Theory
Edward Deci & Richard Ryan (1985)
Self-determination theory proposes that humans have three core psychological needs: autonomy (the need to feel in control of one’s own behaviour), competence (the need to feel effective) and relatedness (the need to feel connected to others). When these needs are met, intrinsic motivation and wellbeing flourish. When they are frustrated, motivation and mental health suffer. This theory has been widely applied in education, healthcare and workplace settings.
Deci, E. L., & Ryan, R. M. (1985). Intrinsic motivation and self-determination in human behavior. Plenum Press.
Sociocultural Theory
Lev Vygotsky (1978)
Vygotsky argued that cognitive development is fundamentally shaped by social interaction and cultural context. Learning does not happen in isolation — it occurs through engagement with more knowledgeable others, within what Vygotsky called the Zone of Proximal Development: the space between what a learner can do independently and what they can achieve with guidance. This theory has profoundly influenced educational psychology and teaching practice.
Vygotsky, L. S. (1978). Mind in society: The development of higher psychological processes. Harvard University Press.
Objectification Theory
Barbara Fredrickson & Tomi-Ann Roberts (1997)
Objectification theory proposes that in cultures that sexually objectify bodies — particularly women’s bodies — individuals internalise an observer’s perspective on their own appearance. This self-objectification leads to habitual body monitoring, body shame, appearance anxiety and reduced psychological wellbeing. The theory has been widely applied in research on body image, eating disorders and gender.
Fredrickson, B. L., & Roberts, T. A. (1997). Objectification theory: Toward understanding women’s lived experiences and mental health risks. Psychology of Women Quarterly, 21(2), 173–206.
Social Identity Theory
Henri Tajfel & John Turner (1979)
Social identity theory proposes that a significant part of a person’s self-concept is derived from their membership of social groups. People naturally categorise themselves and others into groups, favour their own group (in-group bias) and sometimes derogate other groups to maintain a positive social identity. This theory helps explain prejudice, discrimination, group loyalty and intergroup conflict.
Tajfel, H., & Turner, J. C. (1979). An integrative theory of intergroup conflict. In W. G. Austin & S. Worchel (Eds.), The social psychology of intergroup relations (pp. 33–47). Brooks/Cole.
Cognitive Behavioural Theory
Aaron Beck (1960s)
Cognitive Behavioural Theory proposes that thoughts, feelings and behaviours are deeply interconnected. Negative or distorted patterns of thinking — such as catastrophising, black-and-white thinking or personalisation — contribute to emotional distress and unhelpful behaviour. By identifying and challenging these thought patterns, people can change how they feel and behave. CBT is one of the most extensively researched and widely used psychological frameworks in clinical practice.
Beck, A. T. (1979). Cognitive therapy and the emotional disorders. Penguin.
More theories will be added regularly. A comprehensive Dictionary of Theories — fully referenced and expanded — is coming soon.
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