Books like A Box of Matches

The candle problem or candle task, also known as Duncker's candle problem, is a cognitive performance test, measuring the influence of functional fixedness on a participant's problem solving capabilities. The test was created by Gestalt psychologist Karl Duncker and published posthumously in 1945. Duncker originally presented this test in his thesis on problem-solving tasks at Clark University.

The test presents the participant with the following task: how to fix and light a candle on a wall (a cork board) in a way so the candle wax won't drip onto the table below. To do so, one may only use the following along with the candle:

The most efficient solution is to empty the box of thumbtacks, use the thumbtacks to nail the box to the wall, put the candle into the box, and light the candle with the match. The concept of functional fixedness predicts that the participant will only see the box as a device to hold the thumbtacks and not immediately perceive it as a separate and functional component available to be used in solving the task.