People tend to place a higher price on items they own than on identical items they do not. To measure this, you divide participants into two groups and give each person a mug. One group is told the mug is a gift; the other is told to return it after the experiment. When both groups estimate the mug's value, you can compare the two sets of estimates to see whether ownership changes how people judge worth.

Ownership changes how your brain judges worth. When something belongs to you, a mental shortcut kicks in that ties value to possession — and that shortcut isn't always accurate. People tend to place a higher price on items they own than on identical items they do not. You can test this directly by giving participants the same mug, changing only whether they get to keep it, then comparing the two sets of estimates.