Some important prerequisites for this interaction are perception, thought, emotion and will (cognitive psychology). The development of these features (developmental psychology) to the characteristic patterns for different individuals (personality) and the differences between individuals and groups (differential psychology) are important areas.
People are biological creatures, and therefore biological psychology and neuro psychology are important areas related to the natural sciences.
But people are also a product of the external environment, both physical and social. Within psychology the interaction between humans and the environment is studied. In social psychology other people are the important elements in the environment.
In its applications psychology aims to contribute to health and welfare by clarifying human needs and limitations. Therefore methods are developed to influence and treat people as well as environments.
The Greek letter Psi is often used as a symbol of psychology.
