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
A cognitive bias that limits a person to using an object only in the way it is traditionally used. You cannot see that a hammer could be a doorstop or that a credit card could open a lock.
When it shows up
Troubleshooting under pressure when the tools you have are not the ones the problem seems to call for. Creative work where standard materials are being used in non-standard ways. Any situation where a solution requires repurposing. Modern context: A remote team running a retrospective uses only the purpose-built retrospective tool because nobody considers that the shared document they already have open would work better for their specific format.
Failure mode
An object is classified by its usual function and that classification suppresses perception of its other properties. The chair is 'for sitting' so its height is not seen as a step stool. The bucket is 'for carrying water' so its shape is not seen as a helmet.
Countermeasure
Describe objects by their raw properties (length, weight, rigidity, surface) instead of their function names. Ask: 'What does this thing have, not what is it for?' When correction costs more than the bias: In stable, well-understood domains where canonical uses of tools are canonical for good reason. A surgeon using a scalpel as a scalpel is not exhibiting functional fixedness - they are applying domain expertise. Functional fixedness is a problem only when novel combinations are genuinely needed.
Related traps
Also connected in the map6 more, locked
Credit & first seen
DiscoveredDuncker, K. (1945).On problem-solving.Psychological Monographs 58(5) source ↗
Also revealed
Entry #22 of 631 in The Lexicon · see the full Lexicon