B = f (P,E) Behavior is a function of the person in their environment.

[다람쥐]

In 1936, psychologist Kurt Lewin wrote a simple equation that makes a powerful statement: Behavior is a function of the Person in their Environment, or B = f (P,E).

People often choose products not because of what they are, but because of where they are. 

Environment is the invisible hand that shapes human behavior. Despite our unique personalities, certain behaviors tend to arise again and again under certain environmental conditions. In church, people tend to talk in whispers. On a dark street, people act wary and guarded. In this way, the most common form of change is not internal, but external: we are changed by the world around us. Every habit is context dependent.

In 1952, the economist Hawkins Stern described a phenomenon he called Suggestion Impulse Buying, which "is triggered when a shopper sees a product for the first time and visualizes a need for it." In other words, customers will occasionally buy products not because they want them but because of how they are presented to them.