The Candle Problem was posthumously published by Karl Duncker in 1945. Though seemingly straightforward, this cognitive performance test has a little trick up its sleeve. Let's just say this logic puzzle requires some out-of-the-box thinking. Read on to see the problem and solution, and to learn more of the history behind this famous problem.
Here's The Problem
You're in a room with a table pushed against the wall. On it is a box of thumbtacks, matches, and a candle. You must attach the lit candle to the wall in a way that the wax won't drip onto the table or floor. How do you complete this task? Scroll down to read the answer, or watch how it is solved in the video below.
To complete this silly task, you can take the tacks out of their box, tack the box onto the wall, and place the lit candle inside the box. Ta-da! Did you solve it?
Duncker noted that this problem requires participants to overcome their tendency for "functional fixedness." He described that as a "mental block against using an object in a new way that is required to solve a problem." In this problem, the tack box is key. Participants had a hard time seeing the box in any way other than a thing containing tacks. A variation of this problem had the tacks presented to the participants outside the box, and the participants were much more likely to figure out the tack-box-to-wall strategy. The moral of Duncker's research? Think outside the box, literally, and don't be too tied to the usual functions of familiar objects.