Psychology is the study of the behavior of living organisms. People who study behavior are called psychologists. Many studies have been conducted by these people to try to understand why people or animals do the things they do. The four main goals of psychology are to describe what happened, explain why it happened, predict what event might happen next, and modify to prevent unwanted outcomes. Psychologists study the process of thinking, learning, cognition, emotions, motivation, and personality. An example of a study that has been done would be why a dog would salivate at the sound of a bell and show. This behavior is due to the fact that a conditioned stimulus becomes a conditioned response. Another experiment done was with a child and a white mouse to see if the child would be scared if something happened while he grabbed the mouse. There are different types of psychologists for different problems. An example is a school psychologist. In educational and school psychology, they study the educational process and work to promote the intellectual, social and emotional development of children in the school environment. The main type of psychology is called clinical psychology, which specializes in the evaluation, diagnosis, and treatment of mental and behavioral disorders. Behavior is any observable action or reaction of living organisms. There are many levels of behavior studied in psychology. Some psychologists focus on high-level behaviors such as aggression or prejudice. There are four main characteristics necessary for it to be an observable behavior, which are: the organism itself, motivation, knowledge and competence. Behavior cannot be studied without the organism present in the body. Furthermore, to study behavior, motivation must be present because it is an immediate cause of a behavior. Knowledge is something that the organism already knows. To examine it you need to understand the environment and what it knows, thinks and remembers.