Reactivity

Reactivity refers to the human tendency to change their behavior when they know that they are being watched. This is a part of the normal human desire to be perceived in the best possible light, and not be judged in a negative way. In psychological and behavioral research this can be a major problem in that it doesn't give a true picture of the behaviors that are being observed. When a researcher sets up an experiment, this factor has to be taken into account and compensated for.