"People generally like to remain true to their word. Years of psychological research show that if you first make a small commitment to someone, and then that person then asks you to make a larger commitment, you will be more likely to comply with their request.

A common explanation for this phenomenon has to do with cognitive dissonance. Once you make a commitment to an organization, person, or cause, that commitment becomes a part of your self-image. If you are then asked to further demonstrate your commitment, you will be hesitant to renege because doing so would conflict with your new self-image and create a dissonant mental state.

One of the first studies to demonstrate the foot-in-the-door technique was conducted in 1966 by Jonathan L. Freedman and Scott C. Fraser.

The researchers contacted California housewives by telephone and asked them if they would answer some questions about the household products they used. Three days later, they called again and asked if they could send a team of men over to go through their house for two hours to manually take account of all the cleaning products.

Freedman and Fraser found that the women were more than twice as likely to agree to this larger request than a control group that had not initially agreed to the smaller request."