During the formative period of scientific psychology, many attempts have been made to specify the meaning, scope, and definition of psychology. The term ‘psychology’ has been derived from two Greek words, psyche (soul) and logus (science). The literal meaning of psychology is the ‘science of soul’. This was the earliest definition of psychology given by the ancient Greek philosophers. Soul is a philosophical and mystical construct, and cannot be directly observed. Hence, this early definition was rejected. Some philosophers used the term ‘mind’ as a substitute for the word ‘soul’, and defined psychology as the ‘science of mind’. But the term ‘mind’ was as vague and as indistinct as the word ‘soul’. Mind cannot be seen or observed, and cannot be studied scientifically. So this definition was not also acceptable.

Some thinkers viewed that psychology studies human beings and defined psychology as the ‘science of man’. But problems arose once again, because disciplines like physiology and anthropology also study different aspects of human functioning. This definition was also not found to be satisfactory. Some other thinkers defined psychology as the ‘science of mental activity’. But by restricting the scope of psychology to mental activity only, the role of physiological functions that determine mental activity was ignored. Hence, this definition was not complete, and therefore, was rejected.

Wilhelm Wundt established the first psychological laboratory at Leipzig in Germany in 1879, and wanted to give a formal status to psychology as a scientific discipline. He defined psychology as the ‘science of conscious experience’ and proposed introspection (self-observation) as the method for understanding conscious experience. In introspection, a trained person observes and analyzes his conscious experiences, and provides a verbal report to the experimenter. E.B. Titchner accepted Wundt’s definition, and popularized his ideas in the United States. But this definition was later criticized on several grounds. A detailed discussion of Wundt’s ideas and the related criticisms are presented later in the section on ‘Origin and Development of Psychology’.

J.B. Watson took a rigorous scientific approach, and wanted to make the study of psychology more objective and quantitative. Watson was dissatisfied with the philosophical and mentalistic constructs such as ‘soul’, ‘mind’, and ‘consciousness’. He defined psychology as the ‘science of behaviour’ and he established behaviorist school of psychology. By ‘behavior’ Watson meant all the outward and the observable activities of the individual. Watson used objective and experimental methods to study behavior. Watson’s definition was more acceptable compared to others, but it did not provide a complete picture of what psychology is concerned about. Behaviours can be overt (external) activities or covert (internal) mental activities like perceiving, reasoning, thinking, imagining etc. The study of internal mental activities was ignored in the definition given by Watson. Furthermore, Watson undermined the role of the organism in any psychological process, and overemphasized the determining role of the environment. Hence, Watson’s definition could not be considered as a complete and comprehensive definition of psychology.


R.S. Woodworth, a member of the behaviorist school, defined psychology as the scientific study of the activities of the organism in relation to its environment. This definition was broader in scope compared to that given by Watson. By using the expression ‘scientific study of activities’, Woodworth emphasized the need to understand, predict, and control human behaviour. The term ‘activities’ includes both external observable behaviors (e.g., running, playing etc.) and internal mental processes (e.g., perceiving, memory, thinking, reasoning etc.). The term ‘organism’ includes human beings as well as other animals. The expression ‘in relation to the environment’ acknowledges the role of the organism and the environment in shaping the individual’s activities or behavior. Woodworth’s definition was considered a more appropriate and acceptable definition of psychology, but it was not comprehensive and exhaustive.

As psychology advanced, researchers became increasingly aware of the role of consciousness in shaping behavior. Wundt’s ideas, which were rejected almost one hundred years ago, were recognized in different forms. The role of internal mental processes in the field of consciousness is now recognized as a valid subject matter of psychology. Most of the recent textbooks of psychology include behaviors, mental processes, and experiences in the definition of psychology. In the light of these viewpoints, psychology may be defined as the scientific study of behaviours, experiences, and mental processes. This is the most acceptable definition of psychology. The important features of this definition are discussed below:

1. Psychology is a scientific study:

Psychology uses scientific methods for studying behaviours, experiences, and mental processes. Some people have difficulty in thinking of psychology as a science like physics, chemistry, or biology. Science is not defined by ‘what’ it investigates but by ‘how’ investigates. The ‘how’ part is covered by the methods.


Scientists are curious individuals willing to think critically about issues and ideas. They use a mixture of the methods of induction and deduction to investigate a phenomenon. The purpose of science is to understand, predict, and control. When psychologists use an intelligence test, they understand and assess the nature of intelligence in a student, predict his achievement in school, and intervene in promoting the intellectual capacity of the student.

Science produces a systematic and organized body of knowledge, which is relatively objective and verifiable. Psychologists develop laws and principles to understand various dimensions of behaviour. Another researcher can verify the knowledge gained by a psychologist. Since human behaviour is complex, psychologists differ among themselves in their analysis and interpretation. But all go through a systematic procedure of study: identifying a problem, stating hypotheses, designing a research strategy, collecting and analyzing data, interpretation and conclusion, revision of theories.

People sometimes carry wrong notions about what psychologists do. Some believe that psychologists are fortunetellers, know about the future of a person, and can read one’s mind by looking at him. In fact, psychologists do not carry out any of these exercises. Some confuse between psychology and psychiatry. A psychiatrist is a medical professional who has specialized in the medical treatment of mental disorders. A psychologist may not have a medical degree. Those who are clinical and counseling psychologists are trained in the use of counseling and therapy with their clients. Psychology, thus, conforms to the basic principles of the scientific tradition.

2. Psychology studies behaviors:


Behaviors consist of all external and internal activities of the organism. Psychologists study all forms of behaviours from simple reflexes (e.g., knee jerk, eye blinking) to more complex patterns of human behaviour (e.g., reasoning, problem solving, decision-making). Almost all forms of behaviour (simple or complex, verbal or non-verbal, external or internal) are studied by psychologists.

In order to be objective, psychologists use the term ‘response’ to denote behaviors. A response is a measurable activity generated by some sort of ‘stimulus’. A stimulus is defined by any change in the physical energy that is capable of evoking a response. ‘Food’ is a stimulus for the hungry man. His salivation at the sight of food is a response. For some psychologists like Thorndike, and Watson, psychology refers to the understanding of stimulus- response connections.

Behaviours can occur at different levels. Thus psychologists study the behaviors of individuals, groups, organizations, crowds, and communities. They study the behaviors of animals including rats, cats, dogs, and chimpanzees. They use the findings from studies on animals for making inferences about behaviors of human beings. They study all forms of abnormality to understand the causes of abnormal behaviour. Recently, psychologists are focusing on behaviors as they occur in natural settings, and the extent of cultural influences on patterns of behavior. A good understanding of the behaviors is possible only when they are interpreted in proper socio-cultural context. Psychology finds a place in all those spheres, where behaviors of some sort are involved. Accordingly, there are many applications of this discipline, giving rise to a large number of fields of psychology.

3. Psychology studies experiences of people:


In recent years, psychologists have shown interest in both conscious and unconscious experiences of people. Some experiences are very personal, and thus are unique for an individual. Most recent textbooks on psychology include a chapter on consciousness or altered states of consciousness. Consciousness is altered when someone uses drugs, or carries medication, or undergoes hypnosis, or dreams during sleep. Psychologists study these unique personal experiences of the individual.

4. Psychology studies mental processes:

The study of observable behaviors does not provide a complete picture of what goes in the brain. The external world has a mental representation in the brain. These men representations obviously have a physiological base in the form of neuron activities in the brain and body. But these representations cannot fully understood in objective physiological terms. The representation consist of mental processes, which have subjective as well as objective components. The mental processes consist of learning, perception memory, problem solving, thinking, decision-making etc., which involve internal mental activities.

The mental processes cannot be directly observed, but they influent observable behaviors. Hence, psychologists make inferences from observable behaviors regarding the processes that take place internally. We cannot direct observe ‘thinking’ but can know whether or not a person is engaged in thinking by observing his behaviour while solving problems. Similarly, we ask a person to recall the earlier learnt materials to make inferences about his memory processes. Psychologists focus on how information is registered, processing and evaluated by an individual. Even they study the information processing mechanisms in a computer to understand how human brain works. Hence the scientific study of the internal mental processes constitutes an important subject matter of psychology.