Functional Fixedness

candle problem

outside the box by Leo Cullum

Functional fixedness [fiks-ed-nes] is a cognitive bias that limits a person to using an object only in the way it is traditionally used. The concept originated in Gestalt Psychology, which emphasizes holistic processing (e.g., ‘the whole is greater than the sum of its parts’). German American psychologist Karl Duncker defined functional fixedness as a ‘mental block against using an object in a new way that is required to solve a problem.’ This ‘block’ limits the ability of an individual to use components given to them to complete a task, as they cannot move past the original purpose of those components.

For example, if someone needs a paperweight, but they only have a hammer, they may not see how the hammer can be used as a paperweight. Functional fixedness is this inability to see a hammer’s use as anything other than for pounding nails; the person couldn’t think to use the hammer in a way other than in its conventional function. When tested, five year old children show no signs of functional fixedness. At that age, any goal to be achieved with an object is equivalent to any other goal. However, by age seven, children have acquired the tendency to treat the originally intended purpose of an object as special.

The theory of functional fixedness has been studied in experimental paradigms involving solving problems in novel situations in which the subject has the use of a familiar object in an unfamiliar context. The object may be familiar from the subject’s past experience or from previous tasks within an experiment. In a classic 1945 experiment, Duncker gave participants a candle, a box of thumbtacks, and a book of matches, and asked them to attach the candle to the wall so that it did not drip onto the table below. Duncker found that participants tried to attach the candle directly to the wall with the tacks, or to glue it to the wall by melting it. Very few of them thought of using the inside of the box as a candle-holder and tacking this to the wall. In Duncker’s terms, the participants were ‘fixated’ on the box’s normal function of holding thumbtacks and could not reconceptualize it in a manner that allowed them to solve the problem. For instance, participants presented with an empty tack box were two times more likely to solve the problem than those presented with the tack box used as a container

A 2003 study gave a written version of the candlebox problem to undergraduates at Stanford. When the problem was given with identical instructions to those in the original experiment, 23% of students were able to solve the problem. For another group of students, the noun phrases such as ‘box of matches’ were underlined, and for a third group the nouns (e.g., ‘box’) were underlined. For these two groups, 55% and 47% were able to solve the problem effectively. In a follow-up experiment, all the nouns except ‘box’ were underlined and similar results were produced. The authors concluded that students’ performance was contingent on their representation of the lexical concept ‘box’ rather than instructional manipulations. The ability to overcome functional fixedness was contingent on having a flexible representation of the word box which allows students to see that the box can be used when attaching a candle to a wall.

In a two-cord problem subjects are given two cords hanging from the ceiling, and two heavy objects in the room. They are told they must connect the cords, but they are just far enough apart that one cannot reach the other easily. The solution is to tie one of the heavy objects to a cord and be a weight, and swing the cord as a pendulum, catch the rope as it swings while holding on to the other rope, and then tie them together. The participants are split into two groups: Group R completes a pretask of completing an electrical circuit by using a relay, while Group S completes a circuit with a switch. Group R participants were more likely to use the switch as the weight, and Group S were more likely to use the relay. Both groups did so because their previous experience led them to use the objects a certain way, and functional fixedness did not allow them to see the objects as being used for another purpose.

The ‘barometer question’ is an example of an incorrectly designed examination question demonstrating functional fixedness that causes a moral dilemma for the examiner. In its classic form, popularized by American test designer professor Alexander Calandra, the question asked the student to ‘show how it is possible to determine the height of a tall building with the aid of a barometer?’ The examiner was confident that there was one, and only one, correct answer. Contrary to the examiner’s expectations, the student responded with a series of completely different answers. These answers were also correct, yet none of them proved the student’s competence in the specific academic field being tested. Calandra presented the incident as a real-life, first-person experience that occurred during the Sputnik crisis. Calandra’s essay, ‘Angels on a Pin,’ was published in 1959 in ‘Pride,’ a magazine of the American College Public Relations Association.

Researchers have investigated whether functional fixedness is affected by culture. In a recent study, preliminary evidence supporting the universality of functional fixedness was found. The study’s purpose was to test if individuals from non-industrialized societies, specifically with low exposure to ‘high-tech’ artifacts, demonstrated functional fixedness. The study tested the Shuar, hunter-horticulturalists of the Amazon region of Ecuador, and compared them to a control group from an industrial culture. The Shuar community had only been exposed to a limited amount of industrialized artifacts, such as machete, axes, cooking pots, nails, shotguns, and fishhooks (all of which are considered ‘low-tech’).

Two tasks were assessed to participants for the study: the ‘box task,’ where participants had to build a tower to help a character from a fictional storyline to reach another character with a limited set of varied materials; the ‘spoon task,’ where participants were also given a problem to solve based on a fictional story of a rabbit that had to cross a river (materials were used to represent settings) and they were given varied materials including a spoon. In the box-task, participants were slower to select the materials than participants in control conditions, but no difference in time to solve the problem was seen. In the spoon task, participants were slower in selection and completion of task. Results showed that Individuals from non-industrial (‘technologically sparse cultures’) were susceptible to functional fixedness. They were faster to use artifacts without priming than when design function was explained to them. This occurred even though participants were less exposed to industrialized manufactured artifacts, and that the few artifacts they currently use were used in multiple ways regardless of their design.

One method for overcoming a functional fixedness bias is the generic parts technique: for each object, decouple its function from its form. Ask yourself two questions: ‘can I subdivide the current part further?’ (if yes, do so), and ‘does my current description imply a use?’ (if yes, create a more generic description involving its shape and material). For example, initially you may divide a candle into its parts: wick and wax. The word ‘wick’ implies a use: burning to emit light. So, describe it more generically as a string. Since ‘string’ implies a use, describe it more generically as interwoven fibrous strands. Since ‘interwoven fibrous strands’ does not imply a use, stop working on wick and start working on wax. People trained in this technique solved 67% more problems that suffered from functional fixedness than a control group. This technique systematically strips away all the layers of associated uses from an object and its parts.

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