Mere ownership effect
Merely owning something makes you like it more, no trading required.
What it means
The mere ownership effect is the tendency to evaluate an object more favorably simply because one owns it, independent of any decision to keep or sell it. It is closely related to the endowment effect but isolates a different driver: where the endowment effect is usually framed around loss aversion in a willingness-to-pay versus willingness-to-accept gap, the mere ownership effect shows that ownership boosts liking and self-relevance even without an explicit transaction or threatened loss. The leading mechanism is a connection to the self — owned objects become incorporated into one's self-concept, and because people evaluate the self positively, that positivity spills over onto possessions. The effect can appear within seconds of taking possession and even for objects acquired by chance. It matters for marketing tactics such as free trials and 'take it home today,' which manufacture a sense of ownership that inflates valuation and stickiness.
Examples
People who are simply handed a mug rate it as more attractive and valuable than identical mugs they do not own, even before any question of selling it arises.
Take a car home for the weekend and it starts feeling like yours; dealers know the test drive sells better than any brochure, no signature or trade required.
Handed a raffle ticket at the door, people soon rate their number as luckier and nicer than the identical ones around it — a possession acquired seconds ago by pure chance.
First described in Beggan (1992).