Social psychology is the scientific study of how people's thoughts, feelings, and behaviors are influenced by the actual, imagined or implied presence of others. In this definition, scientific refers to the empirical investigation using the scientific method. The terms thoughts, feelings, and behaviors refer to psychological variables that can be measured in humans. The statement that others' presence may be imagined or implied suggests that humans are malleable to social influences even when alone, such as when watching videos, sitting on the toilet, or quietly appreciating art. In such situations, people can be influenced to follow internalized cultural norms. Social psychologists typically explain human behavior as a result of the interaction of mental states and social situations.