You are given a candle, a box of matches, a few thumbtacks, and a very short piece of string with the instruction to mount the candle on a wall. It never occurs to you that you could empty the matchbox and tack it to the wall as a platform for the candle because of .

Functional fixedness      

Explanation:

You are given a candle, a box of matches, a few thumbtacks, and a very short piece of string with the instruction to mount the candle on a wall. It never occurs to you that you could empty the matchbox and tack it to the wall as a platform for the candle because of functional fixedness. Functional  fixedness is a cognitive bias that makes individuals not to see the alternative ways to use an item apart for the traditional purpose for which it was made.

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