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Are You Left or Right Sided?

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

Abstract

Did you know that our brains are split into two parts, right inside our head? One half is the left brain and the other half is the right brain. Some people use one half of the brain more than the other half when they are doing certain activities, like talking or reading. The half that is used is sometimes tied to which hand they prefer to use. If someone likes to use their right hand when doing an activity, like drawing or throwing a ball, do they also prefer to use their right ear, eye, or foot when hearing, seeing, or kicking something? Which side do people use the most? In this science project, you will get to find out!

Objective

Test volunteers to see if their bodies are left-dominant or right-dominant.

Credits

Teisha Rowland, Ph.D., Science Buddies

Sources

Many of the experiments in this project came from the Neuroscience for Kids website developed by by Eric H. Chudler, Ph.D. at the University of Washington:

Cite This Page

MLA Style

Science Buddies Staff. "Are You Left or Right Sided?" Science Buddies. Science Buddies, 6 Oct. 2014. Web. 22 Oct. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBio_p007.shtml?from=Blog>

APA Style

Science Buddies Staff. (2014, October 6). Are You Left or Right Sided?. Retrieved October 22, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBio_p007.shtml?from=Blog

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Last edit date: 2014-10-06

Introduction

Are you right or left handed? Are you better at art, video games, or sports? Are you a good dancer? The things we like to do and what we are good at are often because of how our brain works. Our brain allows us to do and think everything we do, from looking at the sky and thinking about the birds that fly through it to dancing to music. While each person's brain is divided into two sides, called hemispheres, each person's brain is unique in how exactly it is connected and patterned. Ultimately, this has an effect on how the body and brain work together.

The two hemispheres in the brain are known as the left hemisphere and the right hemisphere, as shown in Figure 1 below. In some cases, doing a certain activity may make one hemisphere more active than the other. For example, we know that when someone is processing language (such as talking or reading), one hemisphere is usually more active than the other. However, processing language or doing other activities is not entirely separated into using the right or left hemisphere, or even certain parts of the hemispheres. Different areas of our brain are certainly important for different things, such as language, speech, hearing, sight, movement, memory, and complex thought. But if part of one of the hemispheres is damaged when a person is young, other parts of the brain can often take over doing whatever the damaged part of the brain used to do.

Human Biology science project Image of the brain showing hemispheres.

Figure 1. In this image of the human brain, the left and right hemispheres are divided by a red line.

What do the sides of the brain have to do with what hand you like to use to write your name? As was mentioned, when someone is processing language, one hemisphere is usually working harder than the other one. Specifically, it has been found that right-handed people (people who usually prefer to use their right hand instead of their left hand) usually use the left hemisphere when they are processing language. On the other hand, left-handed people often use the right hemisphere or both hemispheres when doing language-based activities. In summary, there is some correlation between the side we use in our brain and the side we use on our body. The preference to use one side over the other is known by several terms: sidedness, laterality, or left/right dominance.

How does the brain communicate with the rest of your body? Your brain is made up of neurons, which are cells that send certain signals to other cells. These signals are how the cells communicate. The neurons in the brain, and in the different hemispheres, are all connected together in a network. The part of the brain that controls our body movement, called the motor cortex, shown in Figure 2 below, spans both of the hemispheres. It is located approximately where a girl wears a headband, in a stripe from ear to ear on both sides of the brain. This section of the brain controls your voluntary muscle movements in these general steps:

  • Sensory information is sent from the body to the motor cortex by sensory neurons.
  • The signal is processed by neurons in the brain.
  • The brain sends a response signal back to the body using motor neurons which will trigger a voluntary movement.
Human Biology science project  Animation of the motor cortex in the brain.

Figure 2. In this animation, the motor cortex is marked in red. The motor cortex spans both hemispheres in a similar manner, but this animation only shows one hemisphere (Anatomography, 2011).

In this human biology science project, you will test several volunteers for left/right bias in using their hands, feet, ears, and eyes. You will test for sidedness in these parts of their body by having them complete a series of tasks. By testing for sidedness in hand coordination, foot coordination, sight, and hearing you can begin to understand how the brain and body work together. Will most people prefer the same side or different sides? Will you be able to detect any patterns of sidedness?

Terms and Concepts

  • Brain
  • Hemispheres
  • Right-handed
  • Left-handed
  • Sidedness
  • Laterality
  • Left/right dominance
  • Neurons
  • Motor cortex

Questions

  • What is an activity that may make one of the brain's hemispheres more active than the other?
  • Do you think the hand a person uses will match the side they often use for their feet, eyes, and ears?
  • If someone is left-handed but was raised to use his or her right hand for writing, how do you think this will affect their left/right sidedness?

Bibliography

Do further research by visiting the following websites, which give information about left/right sidedness and the motor cortex:

For help creating graphs, try this website:

Materials and Equipment

  • Paper
  • Pen or pencil
  • Scissors
  • Ball
  • Stairs
  • A coin
  • Paper towel tube or toilet paper tube
  • Sea shell
  • Volunteers (at least 10)
  • Lab notebook

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Experimental Procedure

Working with Human Test Subjects

There are special considerations when designing an experiment involving human subjects. Fairs affiliated with Intel International Science and Engineering Fair (ISEF) often require an Informed Consent Form (permission sheet) for every participant who is questioned. Consult the rules and regulations of the science fair that you are entering, prior to performing experiments or surveys. Please refer to the Science Buddies documents Projects Involving Human Subjects and Scientific Review Committee for additional important requirements. If you are working with minors, you must get advance permission from the children's parents or guardians (and teachers if you are performing the test while they are in school) to make sure that it is all right for the children to participate in the science fair project. Here are suggested guidelines for obtaining permission for working with minors:

  1. Write a clear description of your science fair project, what you are studying, and what you hope to learn. Include how the child will be tested. Include a paragraph where you get a parent's or guardian's and/or teacher's signature.
  2. Print out as many copies as you need for each child you will be surveying.
  3. Pass out the permission sheet to the children or to the teachers of the children to give to the parents. You must have permission for all the children in order to be able to use them as test subjects.
  1. For this experiment you will need at least ten volunteers, so start asking around to find willing volunteers!
    1. Each individual will need to do a series of tests: hand dominance, foot dominance, eye dominance, and ear dominance. That is a lot of testing, so be sure that your volunteer can give an adequate amount of time to complete all of your tests.
  2. Make sure you have all of the materials ready so that you will be able to quickly test each volunteer.
    1. For one of the tests, you will need a piece of paper with a small hole cut in it for volunteers to look through. Prepare a piece of paper so that it has a hole in it now.
  3. In your lab notebook, create a data table like Table 1 below to write your results in.
    Volunteer 1 Volunteer 2 Volunteer 3 etc.
Hand DominanceWrite their name    
Use scissors    
Throw a ball    
Foot DominanceKick a ball    
Step up a stair    
Step onto a coin    
Eye DominanceLook in a tube    
Look in a hole    
Look at a finger    
Ear DominanceCup their ear    
Listen to a shell    
Listen through a wall    

Table 1. In your lab notebook, create a data table like this one to record your results in. For each volunteer, you will write whether they used their "Right" or "Left" side to do each task.

  1. Now you are ready to test your volunteers. Do the following tests with each volunteer, one at a time, until you have tested all of the volunteers. For each volunteer, depending on which side they use to do the task, write either "Right" or "Left" in the data table in your lab notebook..
    1. First test hand dominance by doing these three tests:
      1. Ask your volunteer to write their name on a piece of paper using a pen or pencil. Observe your volunteer to see which hand they write their name with and record the result in your data table.
      2. Ask your volunteer to use the scissors to cut a piece of paper. Observe which hand they hold the scissors with when cutting the paper and record the result.
      3. Ask your volunteer to throw a ball, observe which hand they throw the ball with, and record the result.
    2. Next test foot dominance by doing these three tests:
      1. Ask your volunteer to kick a ball, observe which foot they use to kick the ball, and record the result in your data table.
      2. Go to the bottom of a flight of stairs and ask your volunteer to walk up the first few steps. Observe which foot they use to step up the very first step and record the result.
      3. Place a coin on the floor directly in front of your volunteer. Ask your volunteer to step onto the coin, observe which foot they step on the coin with, and record the result.
    3. Next test eye dominance by doing these three tests:
      1. Give your volunteer a paper towel tube or a toilet paper tube and ask them to look at a distant object through it. Observe which eye they use to look through the tube and record the result in your data table.
      2. Give your volunteer the piece of paper you made a hole in and ask them to look through it. Observe which eye they use and record the result.
      3. Hold your finger so that it is centered in front of your volunteer and ask them to close one eye to focus on the finger. Observe which eye they keep open and record the result.
    4. Lastly test ear dominance by doing these three tests:
      1. Stand front and center looking straight at your volunteer, tell your volunteer that you will whisper something in their ear, and ask them to cup their ear. Observe which ear they cup and record the result in your data table.
      2. Give your volunteer a sea shell and ask them to listen to it. Observe which ear they put the shell to and record the result.
      3. Have your volunteer stand facing a wall and then ask them to listen through the wall. Observe which ear they put to the wall and record the result.
  2. After you have given your tests to at least ten volunteers, summarize all of your data together so that you can analyze your results. To do this, make a data table like Table 2 below in your lab notebook and summarize your data in it.
    1. For each volunteer, write "Right" if they used their right hand for two or three of those three dominance tests
    2. For each volunteer, write "Left" if they used their left hand for two or three of those dominance tests.
  Volunteer 1 Volunteer 2 Volunteer 3 etc. Percent Right Percent Left
Hand Dominance      
Foot Dominance      
Eye Dominance      
Ear Dominance      

Table 2. In your lab notebook, make a data table like this one to summarize your results in. For each volunteer, write whether they mostly used their "Right" or "Left" sides to do the different dominance tests.

  1. Calculate the percentage of people who were left or right dominant for using their hands, feet, eyes, and ears. Write these answers in the "Percent Right" and "Percent Left" columns in the data table in your lab notebook.
    1. For example, to calculate what percentage of people were right hand dominant, add up the total number of people who mostly used their right hand instead of their left hand, and divide this number by the total number of people you tested.
      1. For example, if eight out of your ten volunteers mostly used their right hand, then 80 percent of your volunteers were right hand dominant, or right-handed.
      2. You would write this answer in your data table in the "Percent Right" column in the "Hand Dominance" row.
    2. Do this calculation for hand, foot, eye, and ear dominance, for both the percentage that were right dominant and the percentage that were left dominant.
  2. Now take a look at your summary data table and ask yourself some questions:
    1. Are more of your volunteers right-handed or left-handed?
      1. What about right-footed versus left-footed, right-eyed versus left-eyed, and right-eared versus left-eared?
    2. What side is the most common and has the highest percentage in your subjects?
    3. Now ask yourself how many people that are right-handed are also right-footed (and vice versa).
      1. You can calculate a percentage of this by counting the number of people who are both right-handed and right-footed, and dividing by the total number of people who are right-handed. Is the percentage high or low?
      2. You can do a similar calculation for any of the other possible combinations. Do you see a correlation?
  3. Using the data in the "Percent Right" and "Percent Left" columns of your summary data table, you can make two bar graphs, one graph showing the percentage of people who were right-sided and one graph showing the percentage of people who were left-sided.
    1. You can make graphs by hand or use a website like Create a Graph to make a graph on the computer and print.
    2. On the left side of each graph (the y-axis), write a scale for the percentage of people from zero to 100%. On the bottom of the graph (the y-axis), write the dominance test categories (i.e., "Hand Dominance," "Foot Dominance," "Eye Dominance," and "Ear Dominance"). Make a bar for each of the four categories.

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Variations

  • If you collect additional data on your participants, you can see if sidedness is linked to another factor like age or gender. Just add another row to your data tables that collects the type of information you want!
  • Were many of your participants from your family? Sometimes sidedness can run in families. Try to find participants from different families and then group your results by family. Do different families have similar or different percentages?
  • Can you think of other ways to test for sidedness? Think of new, creative ways to test for sidedness using objects around your house or school. Compare the results of your test to those described above. Are the results similar? Did your test work? How might it be useful?
  • For a more advanced science project, you can evaluate your data using statistics. Calculate the standard deviation and margin of error of your experiment. Then perform a t-test to see if your results are statistically significant. You will need to use a high number of participants for this type of study.

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