The History of Psychology

IMPORTANT: All dates on this timeline are approximate and based off a year when the various theories/discoveries were popular or just beginning. An important trend to notice throughout the last century in psychology is that psychologists are understanding more and more how related the mind is to the brain.



Approx. 1890

"Gestalt" is a German word meaning a "form" or a "whole." German psychologists in the early twentieth century began to realize that people tend to organize a gestalt in their minds when given a cluster of sensations. The theory this discovery is trying to prove is that an organized whole is perceived as more than the sum of its parts. The result of this would be that humans organize their sensations into perceptions.


Approx. 1890

Neuropsychology is the study of how the brain can relate to different behaviors and processes. The study is very experimental, as scientists today still don't know everything there is to know about the brain. However, neuropsychologists strive to understand how different behaviors are related to the functioning of the brain.

Operant Conditioning

Approx. 1900

Operant conditioning (also called instrumental learning) is a psychological method where the subject is punished for bad behavior and rewarded for good behavior. This point of this method is to encourage the subject to associate what good outcomes and bad outcomes there are for certain behaviors. A psychologist will use this method to understand how the brain reacts to consequences, and how that modifies behavior.


Approx. 1900

Structuralism was an early school of psychology that sought to understand the adult mind based on a state of consciousness explored with the use of physical sensation, feelings and emotions, and images. The theory was eventually disproved because it was based off of introspection in the human mind, which varies from person to person.

Evolutionary Psychology

Approx. 1910

Evolutionary psychology is an approach to psychology that attempts to explain certain traits in humans as the products of natural selection. It seeks to identify which psychological traits in humans are because of natural selection. This theory was a stepping stone for modern psychology, because before Charles Darwin, humans didn't even know that natural selection existed, and this was taking the theory to an even more advanced level.


Approx. 1913

Behaviorism is when elements of philosophy, methodology, and theory are combined in an approach to psychology. The belief behind this theory is that psychology can be learned both through observable practices in people, and also what goes on in their private mind. Therefore, secrets of psychology could be discovered without prior knowledge of a subject's psychological events or their thoughts and beliefs.


Approx. 1920

Humanism is a philosophy that focuses on the well-being and happiness of a person without basing it off of supernatural forces, i.e. religion. This belief is important to psychology because it emphasizes the uniqueness of a person as an individual, and the study of the whole mind and not just a part of it.

Socio-cultural Psychology

Approx. 1924

Socio-cultural psychology is the study of human subjects and their behavior in a social context. For example, the behavior of a human would be studied while they were in a social setting. Data from these kinds of experiments can determine why humans act in a certain way while surrounded by others.


Approx. 1936

A lobotomy is an operation on the brain in the prefrontal lobe area. The purpose of the operation is to treat mental illness. This kind of surgery was important for psychology because it proved that humans believed the mind was part of the brain, and an operation on the brain could change the personality of a human.


Approx. 1940

Functionalism was a theory studied by psychologists that opposed the prevailing theory of structuralism. Functionalism claimed that psychology should be studied through a person's life and behavior in terms of how they adapt to their environment. Therefore, conclusions about psychology could be made without conducting controlled experiments.

Hierarchy of Needs

Approx. 1943

Abraham Maslow's hierarchy of needs is a theory in psychology that proposes how the development of the human mind happens. The pyramid goes physiological, safety, love/belonging, esteem, and self-actualization. These words were described by Maslow to describe the pattern that human motivations generally move through.

Cognitive Development Theory

Approx. 1950

Developed by Jean Piaget, the cognitive development theory is a comprehensive analysis of how the intelligence of a human being develops, and the nature from which the intelligence comes. Piaget believed that the mind of a child changes and grows due to the environment they are in, which goes against the medieval psychological belief that children are born as mini-adults.


Approx. 1950

Psychotherapy is the treatment of patients with mental disorders by a psychologist rather than a medical doctor. During psychotherapy a psychologist will listen to a patient's moods, feelings, behaviors, etc. in order to better be able to respond to the patient's challenges. The aim of psychotherapy is to increase the well-being of the patient.

Diagnostic and Statistical Manual (DSM)

Approx. 1952

The Diagnostic and Statistical Manual of Mental Disorders is used by psychologists to classify mental disorders in patients. It is not only used by psychologists but also psychiatrists, social workers, and nurses. This manual was a very helpful tool when the first edition came out because it helped professionals to collect accurate health statistics in a population.


Approx. 1960

Psycholinguistics is the psychological study of how linguistic behavior is related to psychological processes, and it includes the process of language acquisition. Understanding how the mind is related to learning languages was helpful for psychologists, because it showed connections that happened in the brain. It also helped to understand children's ability to learn languages.

Attachment Theory

Approx. 1969

Attachment theory is a psychological model that attempts to describe relationships between humans. However, the theory has not been proved as an exact model for relationships. This study attempts to understand how humans react when they are hurt, separated from loved ones, or perceiving a threat. An important part of the attachment theory is that a child needs to develop a positive relationship with a human being in order to be successful socially and emotionally.