Abstract

Objective

The goal of this science fair 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 the 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. Incidentally, most people also have a dominant foot, ear, and eye.

Curiously, the two halves, called 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.

Click here to watch a video of this investigation, produced by DragonflyTV and presented by pbskidsgo.org

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, below, has some ideas you can use to test dogs for paw preference. If you would like to see some ideas for testing paw preference in cats, watch the DragonflyTV video on the right, and join Cleo, Brittany, and Molly as they put Cleo's cats, Nudge, Cle-cle, and Brooklyn through a series of three tests to see which paws the cats use most frequently.

Some things to think about if you will be testing cats:

1. When putting a cat (or a dog) through the "food tube test" (where the animal tries to get food out of a long tube), be sure to place the tube so that when the animal first sees it, the tube is not off to the animal's right or left, but directly in front of the animal, in the middle.
2. When putting a cat through the string or toy test, again, be sure to first show the toy to the cat so that it is in the center of his or her field of view, and not off to one side, as this will influence which paw the cat uses to bat at the toy.
3. In the "smudge test," where a dab of an edible, oily substance is placed just above the cat's nose to see which paw he or she uses to wash it off with, be sure to use something that the cat is not allergic to, and is non-toxic (safe to eat). A dab of wet cat food might be a good choice. Be sure not to use too much, or do this test outside, so that if the cat shakes his or her fur, the substance doesn't fly around the room.
4. Some cats are very sound-sensitive, so be sure to do your trials in a quiet room with few people. Remember the general rules around animals: speak softly and move slowly. Fast motions can frighten many animals. If you need to get your cat's attention, try gentle kissing sounds.
5. Remember that cats, like other mammals, have a circadian rhythm, or daily cycle, that tells them when to sleep, eat, and play or hunt. Many cats like to sleep during the day and play or hunt in the evening or early morning when their traditional prey, like rodents or birds, become active. To get the best results, try to conduct the trials of your experiment at the same time every day, and at times when your cat is most active and interested in food.

Terms, Concepts, and Questions to Start Background Research

• Fine motor control
• Brain hemispheres
• Somatosensory cortex
• Motor cortex
• Paw preference
• Circadian rhythm
• 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

• TPT. (2006). Pet Handedness by Cleo, Brittany, Molly. DragonflyTV, Twin Cities Public Television. Retrieved November 13, 2008, from http://pbskids.org/dragonflytv/show/pethandedness.html
• BBC. (2004). Test Your Pet. Retrieved August 21, 2006, from http://www.bbc.co.uk/nature/animals/pets/testyourpet/flat_alternative.shtml
• WGBH. (1998). Probe the Brain. Retrieved August 21, 2006, from 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. Retrieved August 21, 2006, from http://faculty.washington.edu/chudler/split.html
• Holder, M.K. (2005). What does Handedness Have To Do with Brain Lateralization (and Who Cares?) Retrieved August 21, 2006, from http://www.indiana.edu/~primate/brain.html
• Wikipedia Contributors. (2008, November 13). Lateralization of Brain Function. Wikipedia: The Free Encyclopedia. Retrieved August 21, 2006, from http://en.wikipedia.org/w/index.php?title=Lateralization_of_brain_function&oldid=248451127
• Gabriel, G. (2006). "Left Brain" "Right Brain" The Mind in Two. Retrieved August 22, 2006, from http://www.brainconnection.com/topics/?main=fa/mind-two

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)
• Tube to hold the treat or toy in
• 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.
• Lab notebook

Experimental Procedure

1. 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.
2. For each dog you test, record the age, gender, and results for the following tests of paw preference.
3. 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? Record your observations in your lab notebook.
4. 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).
5. Calculate the percentage of dogs with left paw preference, right paw preference, or no clear paw preference.
6. 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?

• For more science project ideas in this area of science, see Mammalian Biology Project Ideas.

Credits

Andrew Olson, PhD, Science Buddies

Sources

The idea for this science fair project is from:

• Ackourey, A. (2004). Are Dogs Right or Left Pawed Retrieved August 21, 2006, from the following California State Science Fair abstract: http://www.usc.edu/CSSF/History/2004/Projects/J1001.pdf

Last edit date: 2008-11-13 13:24:00