Psychological theories are systems of ideas that can explain certain aspects of human thoughts, behaviors and emotions. Psychology researchers create these theories to make predictions for future human behaviors or events that may take place if certain behaviors exist.

Key Terms

Jean Piaget

Jean Piaget's theory of cognitive development suggests that children move through four different stages of intellectual development which reflect the increasing sophistication of children's thoughts. Child development is determined by biological maturation and interaction with the environment.

Learn More: Piaget's Stages of Cognitive Development


Behaviorism is a theory of learning that states all behaviors are learned through interaction with the environment through a process called conditioning. Thus, behavior is simply a response to environmental stimuli.

Learn More: Behaviorist Approach in Psychology


Sigmund Freud (1856 to 1939) was the founding father of psychoanalysis, a method for treating mental illness and a theory that explains human behavior. His theories are clinically derived, based on what his patients told him during therapy.

Learn More: Sigmund Freud's Influence on Psychology


An approach is a perspective that involves certain assumptions about human behavior: the way people function, which aspects of them are worthy of study, and what research methods are appropriate for undertaking this study. The five major psychological perspectives are biological, psychodynamic, behaviorist, cognitive, and humanistic.

Learn More: Major Perspectives in Modern Psychology


Neuroscience is the branch of science concerned with studying the nervous system. It is a multidisciplinary field integrating numerous perspectives from biology, psychology, and medicine. It consists of several sub-fields ranging from the study of neurochemicals to the study of behavior and thought.

Learn More: What is Neuroscience?

Frequent Asked Questions

The words psychodynamic and psychoanalytic are often confused. Remember that Freud’s theories were psychoanalytic, whereas the term ‘psychodynamic’ refers to both his theories and those of his followers, such as Carl Jung, Anna Freud, and Erik Erikson.

Learn More: Psychodynamic Approach

Developmental psychology is a scientific approach which aims to explain how thinking, feeling, and behavior change throughout a person’s life. A significant proportion of theories within this discipline focus upon development during childhood, as this is the period during an individual’s lifespan when the most change occurs.

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Sigmund Freud proposed that personality development in childhood takes place during five psychosexual stages, which are the oral, anal, phallic, latency, and genital stages.

During each stage, sexual energy (libido) is expressed in different ways and through different body parts.

Learn More: Freud’s Psychosexual Stages of Development

Object permanence means knowing that an object still exists, even if it is hidden. It requires the ability to form a mental representation (i.e. a schema) of the object.

The attainment of object permanence generally signals the transition from the sensorimotor stage to the preoperational stage of development.

Learn More: What Is Object Permanence According To Piaget?

Psychology studies the mind of an individual to understand human behavior and social and emotional reactions, whereas sociology looks beyond individuals and examines societal institutions and groups of people.

Learn More: Similarities and Differences Between Sociology and Psychology

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