Psychology is the scientific study of behavior and mental processes. The goals of psychology are to describe, predict, explain, and control behavior. Early perspectives in psychology included structuralism, functionalism, Gestalt psychology, psychoanalysis, and behaviorism. Modern perspectives include the psychodynamic, behavioral, humanistic, biopsychological, cognitive, sociocultural, evolutionary, and other perspectives. Researchers use various methods including naturalistic observation, surveys, correlation, experiments, case studies, and more to study behavior scientifically while ensuring ethical treatment of participants. Critical thinking is important to evaluate psychological claims.