Objective
In this experiment, you will test volunteers to see if their bodies are left-dominant or right-dominant.
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. Each person's brain is unique in how it is connected and patterned. Ultimately, this has an effect on how the body and brain work together. For example, some people are well coordinated while other people are clumsy. Another example is that some people are ambidextrous (they use both hands very well) but others tend to use one side more than the other.
Each person's brain is divided into two sides, called hemispheres, that control different aspects of our thoughts, activities, and movement. Each side of the brain is divided into smaller areas that are important for different things, like: language, speech, hearing, seeing, movement, memory, and complex thought. All of these regions are interconnected in a network. The left and right hemispheres are also connected to each other through the corpus collossum, a large bundle of nerves in the center of the brain.
The part of the brain that controls our body movement is called the motor cortex. 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 three steps:
- Sensory information is sent from the body to the motor cortex by sensory neurons.
- The signal is processed by interneurons in the brain.
- The brain sends a response signal back to the body using motor neurons which will trigger a voluntary movement.
In this experiment, you will test several volunteers for left/right bias in their motor coordination. You will test for sidedness, or dominance, in 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, Concepts and Questions to Start Background Research
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!
- brain
- hemispheres
- left hemisphere
- right hemisphere
- left/right dominance
- motor cortex
- neuron
Questions
- Will people use one side of their body more than the other?
- Will the hand a person uses match the side they often use for their feet, eyes, and ears?
- What kind of tests can identify you as a left-dominant or right-dominant person?
Bibliography
- Chudler, E.H. 2006. "Right Side / Left Side," Washington University [Accessed December 10, 2006] http://faculty.washington.edu/chudler/rightl.html
- Holder, M.K., 2005. "What does Handedness have to do with Brain Lateralization," Indiana University, Bloomington, IN. [Accessed December 10, 2006] http://www.indiana.edu/~primate/brain.html
- Dubuc, Bruno. 2002. "The Brain From Top to Bottom: Body Movement & the Brain," McGill University, Montreal, Quebec, Canada. [Accessed March 10, 2006] http://thebrain.mcgill.ca/flash/d/d_06/d_06_cr/d_06_cr_mou/d_06_cr_mou.html
- Wikipedia contributors, "Primary motor cortex," Wikipedia, The Free Encyclopedia. [Accessed March 10, 2006] http://en.wikipedia.org/w/index.php?title=Primary_motor_cortex&oldid=116297502
Materials and Equipment
- computer with Internet connection
- pens and pencils
- paper and scissors
- ball
- cup with water (optional)
- fork or spoon and food (optional)
- stairs
- a coin
- paper towel tube
- piece of paper or cardboard with a small hole
- sea shell
- several volunteers
- clipboard to hold data sheets
Experimental Procedure
- For this experiment you will need several volunteers, so start asking around to find willing volunteers!
- 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 you have all of the supplies ready and that your volunteer can give an adequate amount of time to complete all of your tests.
- For each individual, you will need a data sheet to keep track of your test results. Here is a sample data sheet suggested by Dr. Chudler from the Neuroscience for Kids web site: http://faculty.washington.edu/chudler/rltable.html
- Now you are ready to test your volunteers:
- Hand Dominance - Observe your volunteer to see which hand they write their name with, which hand they hold scissors with when cutting a piece of paper, which hand they throw a ball with, which hand they eat with, and which hand they use to drink water out of a cup.
- Foot Dominance - Observe your volunteer to see which foot they use to kick a ball, step up onto a stair, or step onto a coin placed on the floor.
- Eye Dominance - Give your volunteer a paper towel tube and ask them to look at a distant object. Which eye do they use? Then ask them to look through a hole cut out of a piece of paper. Do they use the same eye?
- Ear Dominance
- Stand front and center looking straight at your volunteer and tell your volunteer that you will whisper something in their ear. Which ear do they cup? Give your volunteer a sea shell and ask them to listen to it. Which ear do they use?
- After you have given your tests to several volunteers, you will need to put all of your data together so that you can analyze your results. Here is one idea on how to make a summary table of your data:
| | Hand | Foot | Eye | Ear |
| Left | Right | Left | Right | Left | Right | Left | Right |
| 0 | | | | | | | | |
| 1 | | | | | | | | |
| 2 | | | | | | | | |
| 3 | | | | | | | | |
| 4 | | | | | | | | |
| 5 | | | | | | | | |
| 6 | | | | | | | | |
| 7 | | | | | | | | |
| 8 | | | | | | | | |
| 9 | | | | | | | | |
| 10 | | | | | | | | |
- Now take a look at your data and ask yourself some questions:
- Are more people right-handed or left-handed? You can calculate a percentage by dividing the number of people of each type by the total number of people in your study. You can do the same calculation for the other forms of dominance (foot, eye, and ear). What side is the most common and has the highest percentage in your subjects?
- Now ask yourself how many people that are right-handed are also right-footed (and vice versa). 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? You can do a similar calculation for any of the other possible combinations. Do you see a correlation?
- You can make a bar graph of your data analysis. On the left side of the graph (y-axis), write a scale for the percentage of people from zero to 100%. On the bottom of the graph, write the categories for each analysis. Then using different colors, draw a bar for each of your analyses.
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 column to your study 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 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.
Credits
Sources
Many of the experiments in this project came from the Neuroscience for Kids site developed by by Eric H. Chudler, Ph.D. at the University of Washington:
Last edit date: 2007-04-04 13:00:00
