This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
Definition
The tendency to place a disproportionately high value on products that we have partially created or assembled ourselves.
When it shows up
When evaluating anything you've partially built or assembled yourself; in product design or consumer research. In expert witness testimony: when a specialist forgets what they did not know at the time of an event. In code documentation: when a developer cannot reconstruct the reasoning behind their own decisions three months later.
Failure mode
Over-valuing your own poorly-made thing compared to a better externally-made one. Paying more for flat-pack furniture you assembled than you would for identical pre-assembled furniture.
Countermeasure
Seek external evaluations of things you've built. Ask: "If someone else had built this, what would I pay for it?" Use that answer to calibrate your own assessment.
Related traps
Also connected in the map4 more, locked
Credit & first seen
DiscoveredNorton, M.I., Mochon, D.&Ariely, D. (2012).'The IKEA effect.'Journal of Consumer Psychology 22(3), 453-460 source ↗
Also revealed
Entry #139 of 631 in The Lexicon · see the full Lexicon