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The Endowment Effect: Why What You Own Feels Worth More

Ownership changes the price you put on things, often within minutes of getting them. Run the classic mug experiment on yourself, meet the research behind it, and learn to tell a fair value from an attachment you did not notice forming. Five short chapters, eight quick checks, and a field guide to keep.

Seph Fontane PennockByMichael Callans, MSWReviewed byMichael Callans, MSW
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A cobalt-blue mug with a blank price tag on a wooden desk, a hand beside it hesitating over the price.
Start the courseor download the field guide (PDF) →
Free12 to 15 minutesPrivate
0 / 100points0 / 5 stamps

20 points for the experiment, 10 per completed check. Retries earn full points. First-attempt accuracy is recorded separately.

At your own pace
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.

  1. Kahneman, Knetsch & Thaler (1990). Experimental tests of the endowment effect and the Coase theorem. Classic mug-market experiments.
  2. 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.
  3. 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

  1. Kahneman, Knetsch and Thaler (1990), Experimental tests of the endowment effect and the Coase theorem
  2. Plott and Zeiler (2005), The willingness to pay-willingness to accept gap
  3. 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

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Important: 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. If you are struggling, reach out to a licensed mental-health professional. In an emergency, call your local emergency number or, in the US, call or text 988.