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The Bouba-Kiki Effect

Time Required Very Short (≤ 1 day)
Prerequisites None
Material Availability Readily available
Cost Very Low (under $20)
Safety No issues


I am always amazed when I hear stories of expeditions into native lands, especially when voyagers are able to communicate with native peoples without sharing a language. Are there certain human sounds with meanings that can cross the language barrier? In this experiment you will investigate the Bouba-Kiki Effect to find out if abstract visual properties can be linked to sound.


In this experiment you will find out if certain symbolic characteristics, like sharpness and roundedness, can cross language barriers.


Sara Agee, Ph.D., Science Buddies

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MLA Style

Science Buddies Staff. "The Bouba-Kiki Effect" Science Buddies. Science Buddies, 10 Jan. 2013. Web. 25 July 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBeh_p026.shtml>

APA Style

Science Buddies Staff. (2013, January 10). The Bouba-Kiki Effect. Retrieved July 25, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBeh_p026.shtml

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Last edit date: 2013-01-10


One of the most amazing things humans can do is use language to communicate. Humans have evolved the ability to use language over many thousands of years, resulting in many languages being spoken around the world today. How did our ability to use language evolve? Where did the first use of language come from?

One idea is that the first use of language represented sounds that became linked to concepts through usage. Eventually these sounds and meanings became more complex in structure and more diverse, creating more complex language. This idea brings with it a major question. Were the first sounds arbitrary and random, or were they consistently applied to certain concepts or symbols? You might think that since modern languages have different origins, that different random associations with sounds could be at the root of these differences. However, a psychological phenomenon called the Bouba-Kiki Effect shows a different possibility.

In the Bouba-Kiki Effect, people are shown a pointy picture or a curvy picture and asked to identify it as "Bouba" or "Kiki" even though those are both non-sense words. A surprising number of people, regardless of language, identify the rounded shape as "Bouba" and the pointy shape as "Kiki" even though they had not been told what the words might mean. Even very young children make the same identification most of the time. What does this mean? Is this evidence of a human predisposition to associating certain sounds with abstract concepts?

Most people, when asked, will say that the shape on the left is "Kiki" and that the shape on the right is "Bouba" even though they may not speak the same language and have not been told what the two words mean (Wikipedia, date unknown).

While the deeper meaning behind the Bouba-Kiki Effect is being debated in coffee shops at colleges and universities around the globe, you can turn it into a nifty science fair experiment. You will make your own set of Bouba-Kiki flash cards. Then you will test volunteers with your flash cards to see if you observe the Bouba-Kiki Effect. Will you see it, or will you have the results of a 50–50 random chance event?

Terms and Concepts

To do this type of experiment you should know what the following terms mean. Have an adult help you search the Internet, or take you to your local library to find out more!

  • Bouba-Kiki Effect
  • Language evolution
  • Symbolic thought
  • Abstract shapes


  • How consistent is the Bouba-Kiki Effect?
  • Will it work the same on people of different ages or who speak different languages?
  • Can I reproduce and measure the Bouba-Kiki Effect using flashcards?


Materials and Equipment

  • Colorful markers
  • Index cards
  • Clipboard and pencil

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Experimental Procedure

  1. First, you will need to design your stacks of index cards. Make two stacks, each having 10 index cards.
  2. On one deck of cards, draw pointy, abstract shapes like this:   Kiki
  3. On the other stack, draw round, bubbly shapes like this: Bouba
  4. Shuffle your two decks of cards together a few times, to make them mix at random.
  5. Make a data table for your results and attach it to a clipboard. Notice that the answers your volunteers will give you are not REALLY correct or incorrect, since "Bouba" and "Kiki" are made up words. That is why you see quotes around the terms "correct" and "incorrect" to mean that you are using this term with reservations. Here is an example of how to do this in your data table:

    Volunteer Number of "Correct" Responses Number of "Incorrect" responses Total Number of Responses

  6. Find your first volunteer. Tell them that you will show them a series of cards, and that you want to know if it is Bouba or Kiki but do NOT tell them what Bouba or Kiki mean. If they ask you for a definition, just explain that they are supposed to guess and do their best to decide.
  7. In your data table keep track of the number of "correct" and "incorrect" answers. There are 20 cards total, so the two numbers should add up to 20 when you are done with your volunteer.
  8. Ask as many volunteers as you can find to help you with your experiment, collecting data from each test subject.
  9. When you are finished, add up the total number of responses, the total number of "correct" responses, and the total number of "incorrect" responses for all volunteers.
  10. To calculate the percentage of "correct" answers, divide the total number of "correct" responses by the total number of responses. To calculate the percentage of "incorrect" answers, divide the total number of "incorrect" responses by the total number of responses.
  11. Make a graph of your data to show whether more people were "correct" or "incorrect". What do you think this means?

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  • Does the Bouba-Kiki Effect differ by age group? Ask each volunteer how old they are, and try to get volunteers from a series of age groups. What is the youngest group in which you can observe the Bouba-Kiki Effect?
  • Do you have an English as a Second Language (ESL) program at your school? Do you live near a cultural center where people speak other languages? Try the experiment on people who speak different languages, to see if it still works.
  • In this experiment, you had the volunteers look at pictures you drew and identify them as Bouba or Kiki. Does it work the other way round? To try this experiment, give the volunteers a piece of paper and ask them to draw something that is Bouba or Kiki. Collect all of the drawings and score them for being pointy or rounded in shape.
  • What is it about the words "Bouba" and "Kiki" that make this work? Try an experiment swapping the vowel and consonant sounds, and see what happens for your experiment. Use the words "Bee-Bee" and "Kooka" instead of "Bouba" and "Kiki" when your volunteers are asked to look at the cards. If the results stay the same, then perhaps the consonant sounds of the "B" and the "K" ar most important. If your results switch around, then the vowel sounds of the "ee" and the "oo" may be more important. What happens?

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