The term behavior in psychology refers to any response, reaction, or action people experience toward any stimuli inside or outside the body.

In order to understand behavior, psychology holds five aims: to describe, to explain, to predict, to control, and to improve the behavior. Describing refers to identifying how behavior occurs. Explaining refers to uncovering the causes of behavior. Predicting refers to foreseeing the behavior in different conditions. Controlling refers to changing the behavior by changing its causes. Improving refers to using psychological explanations to promote humans’ wellbeing.

The term dualism refers to separateness of mind (e.g., consciousness) and body (e.g., the brain). According to this approach, humans do have spiritual (mind) and physical part (body) in an isolated way.

Descartes suggested that although the body works like machine having its own principles, the mind influences the working of the body. Descartes indicated an organ (the pineal gland) in the brain, where the mind and physical properties interact in the body. What the mind decides to do, the pineal gland reacts accordingly and flows the fluid into the relevant nerves, which result in movement of relevant muscles. Proposing a relationship between mind and body, Descartes influenced the development of psychology significantly. The idea of mind having control over the body implied that study of it does not have to be metaphysical or unscientific.

While questioning how humans acquire knowledge, idealism not only emphasized the role of the senses as in empiricism, but also the role of the mind. It suggested that by combining and integrating the sensations, perceptions and observations, humans’ mind plays an active role in the development of knowledge. This meant that humans’ mind makes inferences based on the experiences in the world, which are gained through the senses. Thus, according to idealism, humans’ mind is creative or it constructs the knowledge of the world.

Empiricism emphasized the sensations, perceptions and observations, people experience in the world they live in, as bases of their knowledge. According to empiricism, humans gain more complex understandings of themselves and their environment by associating their perceptions, observations, and ideas.

Wilhelm Wundt wrote the first psychology textbook titled Principles of Physiological Psychology.

Method of structuralism was introspection.

Psychoanalytic approach studied unconscious processes of human mind.

According to Gestalt psychology, individual elements of any experience cannot explain the experience itself. This approach argued that the human mind organizes the experience in the way that is not reducible to the sum of its parts. It suggested that elements of any experience interact with each other and humans perceive a pattern or a whole of these interactions, which takes place across time and/or space. Thus, psychology should consider the whole in order to understand its parts because the whole of anything is greater than its parts.

Approach of behaviorism suggested that psychology should study the observable behavior. Behaviorism emphasized the relationship between behavior and environment. It suggested that psychology should question what happens in people’s environment and how they behave accordingly. That is, how the environment shapes the behavior.

Humanistic perspective argued that humans are good in nature and have a potential or natural drive for positive development and change.According to humanistic perspective, humans areable and responsible to make their existence in the world meaningful.

Because its theorists influenced the development of cognitive perspective in psychology. According to cognitive perspective, how humans process the information or the stimuli in the environment influence how they behave. It suggests that humans’ thoughts and interpretations of information and stimuli shape their behaviors. By the 1960s and 1970s, cognitive perspective has largely influenced the studies in psychology. The subjects such as decision-making, problem solving, learning, perception, attention, memory, and language development have been studied in a fame of cognitive perspective.

Psychology has some main subareas, such as, social psychology, clinical psychology, developmental psychology, and industrial and organizational psychology. These subareas are relatively old and extensively contributed tothe theoretical, empirical, and methodological development of psychology.

Clinical psychology studies the behavioral, emotional, and cognitive problems in humans. It aims to understand the determinants of psychological disorders such as stress, depression, anxiety, and phobia.

Social psychology studies human behavior in relation with others’ behavior. It aims to understand how others influence humans’ behaviors, thoughts, and feelings.

Developmental psychology studies human behavior in the context of aging. It aims to understand how human behavior changes with aging across life. Developmental psychology has particular interest in the study of what influences development in the childhood. It attempts to understand how physical, social, emotional and cognitive changes occur in the childhood and how they influence each other.

Industrial and organizational psychology studies human behavior in the context of working people. It aims to understand the relationship between behavior and work performance in settings such as factories, companies, banks, hospitals, schools, and universities. Industrial and organizational psychology attempts to understand the characteristics of problems experienced by working people and develops techniques to help them to do better.

Neuropsychology studies human behavior in the context of the brain and nervous system. It aims to understand the relationship between functions of the brain and nervous system and behavior. Neuropsychology attempts to explain how and why the brain and nervous system function in relation with our behaviors, thoughts, and feelings.

Psychology has also some relatively young and small subareas such as traffic psychology, health psychology, psychology of religion, music psychology, sports psychology, forensic psychology, family psychology, cross cultural psychology, consumer psychology and political psychology