Psychologists demonstrate this by asking a group of people how much they think a water bottle is worth. The group will agree to an amount around $5, and then someone in the group will be given the bottle for free. Then, after an hour, they ask the person how much they would be willing to sell the bottle back to the experimenter for. They usually ask for more money, like $8. Ownership adds special emotional value to things, even if those things were free.
