The Endowment Effect
Why the things you own feel worth more than they are. Run the classic mug experiment on yourself, meet the research behind it, spot the pattern in daily life, and earn five stamps along the way.
Free 12 to 15 minutes Private
0 / 100points0 / 5 stamps
20 points for the experiment, 10 per completed check. Retries earn full points. First-attempt accuracy is recorded separately.
Curious about the science? Sources & research notes
This is an educational thought experiment, not a measure of your susceptibility to bias. The story is fictional. Research results vary with the object, context, instructions, and valuation method.
- Kahneman, Knetsch & Thaler (1990). Experimental tests of the endowment effect and the Coase theorem. Classic mug-market experiments.
- Plott & Zeiler (2005). Willingness to pay, willingness to accept, and experimental procedures. Found no gap under their modified procedures; a gap alone does not establish its cause.
- Morewedge, Shu, Gilbert & Wilson (2009). Ownership-related valuation can matter beyond a simple loss-aversion explanation.
Original story and artwork for Psychology.com. No continuing-education credit is awarded.
Sources
- Kahneman, Knetsch and Thaler (1990), Experimental tests of the endowment effect and the Coase theorem
- Plott and Zeiler (2005), The willingness to pay-willingness to accept gap
- Morewedge, Shu, Gilbert and Wilson (2009), Bad riddance or good rubbish? Ownership and not loss aversion causes the endowment effect
Cite this source
Psychology.com. (2026, September 16). The Endowment Effect. Psychology.com. https://psychology.com/courses/endowment-effect
Note: This is a free educational mini course. It is not therapy, treatment, a psychological assessment or a credential, and no continuing-education credit is awarded.