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Puzzles

Most people reserve the term problem solving for difficult or unique problems. Perception does not seem like problem solving because usually it is fast and automatic. Typically people think of problem solving as difficult mental activity that requires conscious effort.

One example is puzzle solving. Puzzles are problems that are difficult to solve because they require some unusual insight or unexpected mental operation.

Example: Duncker's Candle Problem

What is Duncker's candle problem? What was Duncker's "functional fixity" concept?


Duncker's (1945) "candle problem

Suppose you are presented with a tabletop containing a box full of tacks, a candle, and a matchbook. Your challenge is to find some way to use these materials to mount a candle on the wall and illuminate the room. How can you do it?

Most people start thinking of typical ways to use the objects, such as pinning the candle to the wall...but that won't work...or lighting the candle and dripping wax onto the wall...but that won't work...

The solution, ultimately, involves regarding the container of the tacks as something other than a container, seeing it as a potential platform for the candle. One can empty the box, use a tack to fasten the box to the wall, then drip some wax onto the box and mount the candle on the box. (Several hours later the room will be in flames, but Duncker never discussed that.)

Duncker used the term functional fixity to describe the tendency of people to regard a certain object as having one, fixed function. To solve the puzzle, one must break out of functional fixity and think of an unusual way to use the small cardboard box.

Higgins and Chaires (1980) showed that subjects could be unconsciously "primed" to find the correct solution to the candle problem. First they were asked to participate in a study about long-term memory. They saw slides of common objects. For one group, these objects were described using the word "of" (for example, "a carton of eggs"). For the other group, the same objects were described using the word "and" (for example, "a carton and eggs"). Then both these groups and several control groups were asked to solve the Duncker's candle problem. Only 20% of subjects in the "of" group could solve the candle problem within 10 minutes. A full 80% of subjects in the "and" group were able to solve the problem within 10 minutes.

How was Duncker's candle problem used in research?

Why did changing one word have such a profound effect? Evidently the "and" group was led to think of objects presented together as separate entities. The "of" group was led to think of objects presented together as interacting wholes. Neither group was aware that they had been primed for the puzzle-solving part of the experiment, so this is an example of how unconscious or automatic forms of processing can influence which ideas enter attention.

What sorts of puzzles are not particularly revealing of intelligence? Which ones tend to require a higher IQ?

In general, solving a puzzle requires (1) ignoring obvious solutions that do not work, and (2) trying out unusual approaches. Whether a person stumbles onto the proper unusual approach no doubt depends upon all sorts of influences, conscious and unconscious.

Not all puzzles are equally revealing of intelligence. Sternberg and Davidson (1982) point out that many puzzles merely require that you stumble on a "trick." Puzzles that correlate with high IQ scores are those that present both relevant and irrelevant clues, requiring the puzzle solver to ignore obvious but irrelevant clues while trying out unusual solutions.


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