Objective
The goal of this project is to determine whether non-primate mammals (e.g., dogs or cats) have a paw preference, which might indicate lateralization of function in the brain.
Introduction
Did you know that different parts of the brain are specialized for doing different things? In mammals, for example, there are specific areas of brain devoted to vision, hearing, touch, smell, and movement.
Most people have a distinct hand preference for actions that involve fine motor control such as writing or throwing a ball or frisbee. Incidentally, most people also have a dominant foot, ear, and eye.
Curiously, the two halves (hemispheres) of the brain have some specialized functions (in the majority of the population). For most people, the brain areas involved in producing and understanding language (both spoken and written) are in the left hemisphere. The right hemisphere (again, in most people) is crucial for understanding spatial relationships: navigating through your house, for example, or recognizing where a piece fits in a jigsaw puzzle.
Another interesting fact about the two sides of the brain is that connections from the cortex to the body are "crossed." The left side of body is mapped to the somatosenory cortex in the right hemisphere of the brain, and is controlled by the right hemisphere's motor cortex. The reverse holds for the right side of the body. So when you move your right hand to pick something up, the "command" to initiate the action originated in your left motor cortex.
What about other animals? For example, do pets like dogs or cats have a paw preference? The Experimental Procedure section has some ideas you can use to test dogs (or cats) for paw preference.
Terms, Concepts and Questions to Start Background Research
To do this project, you should do research that enables you to
understand the following terms and concepts:
- paw preference,
- fine motor control,
- motor cortex,
- somatosensory cortex,
- brain hemispheres,
- brain lateralization.
Questions
- An animal's right paw is controlled by the motor cortex in which brain hemisphere?
- If you touch your pet on it's left paw, you will activate neurons in the sensory cortex of which side of the brain?
Bibliography
- BBC, 2004. "Test Your Pet," BBC, Science & Nature [accessed August 21, 2006] http://www.bbc.co.uk/nature/animals/pets/testyourpet/flat_alternative.shtml.
- WGBH, 1998. "Probe the Brain," A Science Odyssey: You Try It, PBS [accessed August 21, 2006] http://www.pbs.org/wgbh/aso/tryit/brain/#.
- For information on brain lateralization and handedness in humans, try these references:
- Chudler, E.H., 2006. "Hemispheres," Neuroscience for Kids, University of Washington [accessed August 21, 2006] http://faculty.washington.edu/chudler/split.html.
- Holder, M.K., 2005. "What does Handedness Have To Do with Brain Lateralization (and Who Cares?)" Handedness Research Institute, Indiana University [accessed August 21, 2006] http://www.indiana.edu/~primate/brain.html.
- Wikipedia contributors, 2006. "Lateralization of Brain Function," Wikipedia, The Free Encyclopedia [accessed August 21, 2006] http://en.wikipedia.org/w/index.php?title=Lateralization_of_brain_function&oldid=70457038.
- Gabriel, Gerald, 2006. "'Left Brain' 'Right Brain': The Mind in Two," BrainConnection.com, Scientific Learning Corp. [accessed August 22, 2006] http://www.brainconnection.com/topics/?main=fa/mind-two.
Materials and Equipment
To do this experiment you will need the following materials and equipment:
- a large number (50–100 would be good) of pet dogs (or cats) to test for paw preference:
- perhaps there is a nearby park where owners bring their dogs for exercise,
- see the Science Buddies resource, How Many Participants Do I Need?, to see understand the reasons for a large number of test subjects;
- small treats or toys for the dogs (or cats),
- a tube to hold the treat or toy.
- Note: instead of using a tube, you might place the treat under a piece of furniture, where it will be within reach of a paw, but out of reach of the head.
Experimental Procedure
- Do your background research and make sure that you understand the terms, concepts, and questions above. More advanced students should also do research into current theories on the advantages (and disadvantages) conferred by lateralization of function in the brain.
- For each dog you test, record the age, gender, and results for the following tests of paw preference.
- Shake A Paw
- Have the dog sit for you.
- Extend a hand and give the command "shake" or "shake a paw."
- Record which paw the dog places on your hand.
- Take a short break, allowing the dog to get up and move around.
- Have the dog sit for you again and repeat the test. Do at least three tests with your right hand and at least three tests with your left hand.
- Does the dog always respond with the same paw? Does it matter which hand you offer to the dog?
- Get a Treat
- Place a treat (or toy) inside a tube large enough for the dog's paw, but too small for its mouth.
- Show the dog the treat, then place the tube down in front of the dog.
- Observe the dog's behavior. If he tries to extract the treat from the tube, which paw does it use?
- As an alternative to placing a treat in a tube, you can put it underneath a piece of furniture, where it can only be reached with a paw.
- As before, take a short break and then repeat the test (at least twice more).
- Calculate the percentage of dogs with left paw preference, right paw preference, or no clear paw preference.
- How do these results compare to handedness in humans?
Variations
- Can you devise another test of paw preference in pets? How do the results of your test compare with results from the tests above?
- Compared to dogs with no paw preference, do dogs with a definite paw preference perform better, worse, or the same on other tests of canine intelligence? For ideas of other tests to try, see BBC, 2004. "Test Your Pet," BBC, Science & Nature [accessed August 21, 2006] http://www.bbc.co.uk/nature/animals/pets/testyourpet/flat_alternative.shtml).
- Can you think of a way to test people for foot preference? How about a way to test which ear is dominant, or which eye? Do these always match with hand preference?
Credits
Andrew Olson, Ph.D., Science Buddies
Sources
The idea for this project is from:
Last edit date: 2006-08-31 22:00:00
