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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.

The great majority of people have a distinct hand preference. How about animals like dogs or cats? Do they show a paw preference? If you like animals, this science fair project might be for you.

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.

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, 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 in the Bibliography, 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:

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. 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. 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. 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. 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 and Concepts

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?