Disturbance in the physiology of the individual.

Among psychologists and psychiatrists, stress refers to a psychological reaction within the person to events that generate strong emotion that cannot be easily regulated; for other social scientists, the term stress is used to describe a disturbance in the individual's physiology. These two definitions of stress are not identical. For example, a fall from a tree that leads to a broken arm creates physiological changes in a child that would be regarded as stressful, for there is a cascade of biological events that occurs in such an act of harm to the child. However, many children who have had such falls are not necessarily psychologically upset, anxious, or fearful, even though there was a physiological stress reaction.

On the other hand, a child who believes his parent does not like him, experiences rejection from a friend, or is feeling guilt over...