__

First, I would like to dedicate this project to my beloved guinea pig Spike. Secondly, a lot of people helped me throughout the course of this project, and I would like to stop now, and thank them. First of all, thank you to all the pet owners and their pets, for without them, this project wouldn_t have been possible. I would like to thank my teachers, especially Mrs. Van Iderstein for their continuous support, wisdom and guidance. I would like to thank the librarians of the Downers Grove Library for helping me find information when it was scarce; also Mrs. King and Dr. Jackie Vernot for information. Thank you to my friends Laura, Colleen, and Katie and other classmates who gave me helpful advice, my neighbor Evie who helped edit my paper. Thanks to my sisters Karen and Laura who were my loyal assistants. Finally, I would like to thank my parents for helping me throughout this project, driving me around, giving various tips, paying for the treats and copies used, and always being there for me. Thank you.

The purpose of my project is to find out which of the following animals can discriminate between a red and a blue light the best: horse, dog, cat, and guinea pig. My hypothesis is that the guinea pigs will be the best, then horses, dogs, and finally cats. I came to this hypothesis because first of all, all of my guinea pig sources were in agreement that they see color, and I have noticed that my guinea pigs seem to see colors. For example, we have given them store bought treats that look like little miniature cheese-puffs. They are all exactly alike, except some are red and some are blue. My guinea pigs seem to prefer the red ones, and eat them first. I hypothesized that horses are second because most of the sources thought that they could see some colors. Dogs are next because more sources for dogs than cats say that they can see colors.

Do animals see color? Veterinary vision specialist, Dr. Jackie Vernot, was asked this question.

"Every domestic animal has the right vision cells for color perception--red, yellow, and blue--so that theoretically they should see full color spectrum, but we don_t know what their brains do. There have been vision studies done in animals as primitive as sharks, and they can tell the difference between red and blue," said Dr. Vernot.

Do horses (equus caballus) see colors? To find out, we must also learn how their eyes work. A horse_s eyes are wired differently then human_s. The assortment of nerves at the back of the eye that are stimulated by light send signals to the brain, and are really an extension of the brain (Budiansky, 1997).

Wild horses rely on their senses for survival. A horse_s eye is large in comparison to other animals, which suggests a heavy reliance on sight for survival (Edwards, 1991). Even a domestic horse_s senses are still acute. Each of the horse_s eyes work independently to cover a semi circle and there_s a spot in the front where they overlap (Vogal, 1995). Just because both eyes overlap, doesn_t mean that the brain is actually making use of the information to make a three-D picture. Their forward field of vision is restricted by the shape of their skull (Flade, 1987). Because horses see two different pictures, they often wear blinders, and training is done on both sides of the horse(Mills, 1988). Horses can see three hundred degrees around them and with a slight turn of their head, they can see in a complete circle around them (Flade, 1987). A horses_ blind spots are right under it_s nose and behind its rump. When a horse jumps over an obstacle, it disappears from its vision, so it must trust its rider (Smith, 1991). Horses naturally walk in a zigzag pattern, giving them panoramic vision (Flade, 1987). The horizontal shape of the pupil helps to see a broad distance (Smith, 1991). Horses are fooled by the same optical illusions that humans are, showing that they have perspective (Budiansky, 1997). Horses have little use for stereoscopic vision for judging distances as compared to humans (Vogal, 1995). A one-eyed horse can judge distances(Vogal, 1995), by size changes (Smith, 1991), but horses have difficulty in assessing the depth of an object (Flade, 1987).

While the majority of horses have brown pigmented eyes, some horses have no pigment in their iris, which has no effect on horse vision (Vogal, 1995). Horse_s eyes have a greater speed of reaction compared to all the other senses (Flade, 1987).

Compared to other parts of the horse, little research has been done on vision, but the study of the physical structure of the eye gives us interesting clues (Budiansky, 1997). The horse has cauliflower shaped, black bodies in the iris called corpora nigra (Vogal, 1995). The cornea nigra is a lump on the upper edge of the iris, which works like a shade to keep out excess light. Albino horses might not have a cornea nigra, which is partly why they are sensitive to light. The sclera is the white on the eye, and it usually don_t show, except for Appaloosas. Horses do not cry, but they do have tears. Their eyes are constantly producing tears to lubricate and cleanse the eye. Most horses have eyelashes on the upper eyelid only. Horses also have a third eyelid which acts like a windshield wiper (Smith, 1991). Because of horses_ large eyes, they have good night vision (Edwards, 1991) compared to other mammals (Flade, 1987).

Horses are thought to focus by raising and lowering their head, not altering the shape of lens (Edwards, 1991). It_s hard for a horse to focus in front of it because of the placement of the eyes on the side of the head. Horses distinguish other horses or another species by their silhouette, not body forms (Chapple, 1987). Horses have great visual acuity. They have the ability to distinguish details at one fiftieth of a degree (Budiansky, 1997). Horses are reputed to have ramp retina. The retina is not equidistant from the lens. Instead, it is tilted forward at the bottom, so the horse has to tilt it_s head to bring objects into focus. When its head is lowered, then it focusing on a far away object. When its head is up then it is focusing on a close object. Because of the natural slope of the horses_ head it can see the ground clearly when grazing. The only other animal who is thought to have this trait is the marine stingray (Sinclair, 1985). Some scientists challenge the idea of ramp retina. A Canadian study showed no evidence of it. It found an area in the retina with a high concentration of photoreceptors, similar to a forvea. This contradicts the idea of a ramp retina (Sinclair, 1985). A study done in nineteen seventy five firmly discredited it (Budiansky, 1997).

The light enters the eye through the clear cornea which covers the eye (Chapple, 1987). Beneath the cornea is the aqueous humor, which holds the eyes_ shape, and lubricates the eye and iris (Smith, 1991). It then moves through the pupil and passes the iris (Chapple, 1987). The iris is a muscular structure which constricts and expands to let in more or less light, depending on how much is shining in to eye, to the back of the eye. Light then travels to the lens. The lens are an oval structure located behind the pupil (Smith, 1991). A horse_s lens does not change shape (Mills, 1988). The horse has a restricted capacity for adjusting the lens to changes of distances, so if a horse wants to get sharp vision for 10-16 feet, then it must lower its head. In general horses_ vision works as a wide angled lens. In distances closer than sixteen feet, very slight changes can be perceived and interpreted. For example, circus horses have been trained to notice changes with 0.2 millimeters difference (Flade, 1987). After the lens, light moves to the retina (Chapple, 1987). After the light travels through a liquid called vitreous humor, it then goes to the retina, which gathers information and sends it to the brain through the optic nerve. There are two types of photoreceptors in the retina (Smith, 1991). A strip of highly sensitive cells called the ganglia were found in the back of the retina. They are so concentrated, in every square millimeter there are five thousand cells (Budiansky, 1997). Behind the retina is the tapetum (Chapple, 1987). The tapetum is a florescent, zinciferous, screen in the back of the eye, that reflects incident light rays, thereby increasing the light intake. This works only in semi darkness (Flade, 1987). The tapetum is what gives animals "green eyes" at night (Smith, 1991). Finally the light, goes through the optic nerve, and then on to the brain (Chapple, 1987).

There is much disagreement concerning color perception in horses. It has been suggested that horses do not see colors as we do (Mills, 1988). Whether a horse sees color or not, is a controversy, and it probably sees shades of grays and changes in brightness more than actual color (Smith, 1991). Horses are quite good at seeing colors (Ziesmann, 1998). Horses are color blind (Seddon, 1988). Horses can see yellow the best, in addition to orange, red, and green, and they have trouble with blue and purple (McBane, 1991). Some authorities claim horses are color blind, but horse owners say they can feel a different reaction to different colors (Stoneridge, 1990). The horses color spectrum is more restricted, and they have difficulty seeing the colors at the end (Flade, 1987). Horses do not really have a need to see color, except for helping them see through camouflage and making ambushes harder (Budiansky, 1997). Cones and rods are both found in the retina. Horses have more cones than rods; the cones work in daylight and recognize color while the rods work in low light (Smith, 1991). However, cones are needed to see well in bright light as well as for color. Therefore, the horse could see color as the result of the need to see well in the day. It takes more than one kind of cone to see all the colors, because each type of cone is more sensitive to light of a certain wavelength. The cone absorbs more when the incoming light match its optical wavelength. For example, to see blue you need to have cones that are sensitive to the amount of light that bounces off the object. The strength of the nerve signal drops off as the wavelength is farther from the optical wavelength. One type of cone can not, by itself distinguish between a reduction in intensity and shift in color, and they both will cause a drop off in response. Humans have three kinds of cones: red, blue, and green sensitive. By a comparison of the responses in cones, the brain sorts out where in the spectrum the color falls. Studies suggest that horses are dichromate, that is, they have two different types of cones, and therefore a limited color perception.

Testing color vision is tricky because they can pick up different brightness, but you can control this by being sure the reflections are matched. David Pick did a study on color perception in horses and his results showed that in a hundred trials, the horses could distinguish red from gray; in two hundred and forty three trials they could distinguish blue from gray; but in one thousand, four hundred trials they could not pick green from gray. Colors that fall between red and green stimulate cones equally and weakly, and because of that, reds, orange, and possibly yellow all look the same (Budiansky, 1997). Brian Timney, Ph.D. has worked on testing color vision in horses. You can_t just put two screens in front of a horse and see if they can tell the difference because they might be able to see one of the colors, but not both. To eliminate this variable, Timney asked a horse to chose the color on a gray background. He would then vary the gray brightness, and see what the horse did. His results were that horses could pick up blue and red on any background color, but could not pick up yellow or green on an equal color background (Equus, 1999).

A possible example of horses seeing and reacting to colors is the carriage horses_ unexpected response to "Cows on Parade" in Chicago. The horses were terrified of the cows, especially "Limoosine" a cow painted to look like a limousine. This surprised everyone who never thought the horses, who are used to cars, motorcycles, and fireworks, would be scared of the cows. The owner of the stable thinks that it is the size, colors, outrageous patterns, and the charging position of some that scared them. To solve the problem, cow therapy was started. They started the horses out with a white and black cow in the paddock with the horses. The cow was then painted orange, and then a colorful, psychedelic design. Each time the horses would start out wary at first, and then one would knock the cow over. All but two of the horses got over their fear (Sullivan, 1999 ). Another example is a horse that dislikes all paint or spotted horses (Jodi, 1999).

Do dogs (canis familiaris) see color?

A dog_s eyes are disproportionately large for a domestic animal in comparison to it_s body weight, but the smaller the dog is, the more proportionate they are (Sylvester, 1993). The farther the eyes are to the side, the greater the field of vision is, which helps dogs to hunt (Case, 1999). In conviliner breeds such as Bull Terriers, Greyhounds, and Bedlington terriers, and other dogs with a rounded skull, the eyes tend to bulge (Sylvester, 1993). Dogs with longer noses, such as Greyhounds, Afghan hounds, Deer hounds, Whippets, and Irish Wolf hounds, are dogs who hunt mostly from sight (Bordwell, 1994). Brachycephalic dogs who have frontally placed eyes can see two hundred degrees, while doichocephalic dogs with side eyes have two hundred and seventy degrees for their field of vision. Humans can see one hundred degrees around. The greater field of vision a dog has, the smaller binocular vision it has, which contributes to bad focusing (Case, 1999). Dogs have relatively poor eyesight, and some breeds see better at night (Sylvester, 1993). Since wolves hunt at night, dogs eyes are specially built for night vision. In fact, dogs are three times more capable of detecting low intensities of light then humans (Case, 1999).

Dogs eyes have an important role in dominance. When two dogs meet, they will stare at each other (Coren, 1994). The less dominate dog will look away first (Sylvester, 1993). Researchers have concluded that dogs are nearsighted and have poor vision accommodation (Carlson, 1992). Dogs cannot see things clearly and in focus, in fact their vision is equivalent to that of a middle aged person with bifocals (Carlson, 1992). The dog, being a predator is far sighted (Sinclair, 1985).

The eye is an organ with several parts. The eyeball itself is seated in a cushion of fat which protects it from its bony socket, and seven muscles help to stabilize the eye. The eyelids are tight folds of skin that support the eye. Dogs have a third eyelid called the nictitating membrane which acts as a windshield wiper by cleaning the eye. It_s sometimes called the haw. Eyelids don_t actually touch the eye, but rather a layer of tears (Carlson, 1992). The tears cleanse and lubricate the eye, and also prevent bacteria from spreading. The front of the eye is rimmed with a narrow portion of white called the sclera. It_s covered by a slippery layer called conjunctiva. Most of the eye is pigmented, and the pigment is mostly found in the iris. Both the iris and the pupil are covered by a layer of thick transparent cells called the cornea. The cornea is the window that light first passes through and then passes on through one of the eyes two chambers, called the anterior chamber. Then the light moves to the pupil (Carlson, 1992). Dogs have circular pupils (Coren, 1994). Then it passes through the lens (Carlson, 1992). The lens have less accommodation than cats (Case, 1999). A dog_s lens are bigger than humans, perhaps to compensate for no accommodation power (Sinclair, 1985). Next light goes to the iris which contracts or expands depending on the amount of light. The light crosses the posterior chamber, and is received by the retina. In the retina there are many photoreceptors for the detection of light, which enhances nighttime vision (Carlson, 1992). The retina is composed of rods which are capable of working in low light. Behind the retina there is a highly reflective layer of cells called the tapetum lumcidum. When the light hits the tapetum, the light is reflected back through the rods, therefore doubling the effect (Bordwell, 1994). The tapetum increase the gathering capability by forty percent (Case, 1999). In the retina the light is converted to nerve impulses and is sent through the optic nerve to the brain (Carlson, 1992).

Similar to horses, there are many discrepancies on this topic. The retina does not have many specialized cells that distinguish color. Dogs see black and whites and various grays (Carlson, 1992). The retina lacks the cells needed to see color (Bordwell, 1994). Because of the low amount of cones in a dog_s eyes, they were thought to be color blind. But recent studies show that they can see green, blue, and their mixture, but no reds, therefore making them a dichromatic animal (Case, 1999). For a long time dogs were thought to see no color. But current thinking is that they have limited color perception, and are probably dichromatic, seeing only blues (Sinclair, 1985). Dogs are color blind (Ziesman, 1998) and (Seddon, 1988). Dogs have very weak color perception, if any (Sinclair, 1992). It is a mistake to think that dogs can only see black and white, because they really see a portion of the visible spectrum. Dogs have cones that correspond to the bluish hues and red-yellow hues. The colors that they see are almost identical to that of a red-green color blind human. Scientists test this by shining a beam of colored light into the dog_s eye and analyzing the spectrum that is reflected back. The results are compared to the human_s reflection in the same test. Another test is when the dogs "tell" us what they see. This is done by setting three lights, of which two are the same color, in front of the dog, who is then trained to pick out the different one. By changing the colors, and repeating the process, scientists have learned that dogs see in black and white with shades of gray, red, yellow, and blue thrown in (Popular Science, 1999). Dogs can see blue-violet and yellow, and use cues other than color. For example, seeing-eye dogs notice the brightness, positioning, and traffic flow, not the color (Probst, 1999).

Do cats (felis) see colors?

Vision is a cat_s most important sense (Rutherford, 1992). Its eyes are very large in relation to the skull, which is important for predators. As a predator, cats always eat the liver of the prey first, which contains vitamin A two, and helps improve night vision (Morris, 1997). Its eyes are adjusted for night vision. Because the cat has a two hundred and eighty five degree field of vision, and one hundred and thirty of it is binocular, cats can judge distances better than humans. Most cats see shapes as well as us, although Siamese tend to have less ability to focus, due to a mutation in their genes (Rutherford, 1992).

Cats have a third eyelid called the nictiting membrane, which is usually hidden from view. The eye is kept moist and clean by tears. The light enters the cornea. The front surface of the eye is covered with the cornea, a wide transparent aperture, which is larger and more curved than humans because of a limited accommodative power of lens. The rest of the eye is covered in a white, fiberous shell called the sclera . The light then moves through the choriod. The internal portion of the sclera is a layer of tissue containing many blood cells called the chorid. Then the light crosses the front chamber. The front chamber is filled with a liquid called aqueous humour, and is positioned in between the sclera and the iris (Rutherford, 1992). The light then moves through the pupil. The cats_ pupil can expand to an enormous size(ninety percent, Morris, 1997) in the dark, and shrink to a narrow slit in the light (Clutton, 1991). The reason why the slits are vertical is that the cat can lower its eyelids to block out even more light (Morris, 1997). Next it moves through the iris. The iris opens and closes the pupil. The light moves through the lens next. Behind the iris is a crystalline lens that is one half inch in diameter and occupies more then one tenth of the eyes_ volume. The lens is held in place by muscles that contract to vary the curve, which insures a focused image being projected to the retina (Rutherford, 1992). After the light passes through the back chamber, filled with a gel-like substance called vitreous humor, it moves to the retina. The retina is attached to the choriod, and is an extension of the optic nerve (Fogle, 1999). Two kinds of cells are found there, the rods and the cones. Cats have more rods than cones(Rutherford, 1992). The light bounces off the tapetum. Cats can see six times as good as humans in the dark. This is partly because of the tapetum made of fibrosum (Clutton, 1991),which is highly effective. Even with the tapetum, cats cannot see in complete darkness (Morris, 1997). The light then goes through the optic nerve to the brain.

Researchers are unsure if cats can see color. Cats have no cones that react to red, and the blue and green cones that they do have are far fewer than humans. It was once thought that they saw everything in a light blue color, but now it_s thought that they see more colors (Rutherford, 1992). It_s not very important to cats to see colors. Until nineteen forty, cats were thought not to be able to see color. Its now known that cats can see color, but not with much finesse. They can distinguish between red, yellow, blue, and green compared to gray, green and blue compared to red and yellow and green compared to blue (Morris, 1997). Most experts believe that cats are not color blind, and can see blues, yellows, greens, and no red (Alderton, 1983). Cats respond more to shape than color. For a long time it was assumed that cats, who have a middle and short wavelength cone, but no long cone, had no color perception. Current thinking is that they are similar to humans who are red-green blind, so they perceive red as dark, and green as white. A cats_ color perception is best under mesopic conditions, such as early morning or late afternoon, because in bright light, the rods cease to function, and since cats have so few cones, vision is poor in bright light. Cones and rods use the same neural pathways, which means when both are activated, the result is a reduction of color signal (Morris, 1997). Cats see colors poorly (Ziesmann, 1998). Cats are color blind (Seddon, 1988). Cats have pale color vision that is better than dogs (Sinclair, 1992).

There is not a lot of information available for guinea pig_s eye vision. The scientific name for guinea pigs is cavia porcellus (Downers Grove Veterinary Clinic, 1999). Peter Gurney_s, one of the well known experts on guinea pigs, email about this subject was, "I tried researching into this years ago, but there is a dearth of information on it."

Training can be done if approached with patience and positive reinforcement (Barrie, 1994). A guinea pig_s healthy eyes should be bright, with no discharge (Pavia, 1997), shiny, slightly moist (Altman, 1997), but should not be slimy and wet (Ritter, 1982). They should be no signs of weeping (Kelsey-Wood, 1999) red, or half closed (Ritter, 1982). Eyes are one of the first indicators of sickness (Steinkamp, 1996), although some things like pea eye or blindness are hereditary (Curran, 1995). Guinea Pigs have protruding eyebrows that are sensitive to touch. This eyebrow is above the eye, and looks like a whisker. The eyelids clean dust from the eye when the animal blinks (Evans, 1992). Guinea pigs do not have a tapetum (Nelson, 1995). The structure of a guinea pig_s eye is almost identical to that of a dog, except it lacks the tapetum (Copper, 1975).

Because of the positioning of the eyes, guinea pigs can see in front, and well on the side. This is needed in the wild (Altman, 1997). Even when a guinea pig is eating, it can tell if something is creeping up behind it. Since it_s prey, the eyes are always watching for predators. Another effect of being prey is that guinea pig babies are born with their eyes open and fully operational (Evans, 1992).

Guinea pigs can, at very least, distinguish between red, yellow, blue, and green. This is important for feeding (Altman, 1997). Guinea pigs are quite good at perceiving colors (Ziesmann, 1998).

7 watt, night light size blue light bulb, with extra replacement bulbs

7 watt, night light size red light bulb, with extra replacement bulbs

2 light bulb sockets with an on/off switch

1 meterstick

1 ruler

2 twister ties

2 blocks of wood 4 1/2 inches by 4 1/2 inches, for mounting the light sockets

1 Nikon FE camera

1 power drill

60 pieces of carrots cut into 8 cm segments

1 lead rope

1 halter

1 disposable pie tin

1 twelve year old Thoroughbred gelding(fixed male) (Shamus)

1 eight and a half year old Trakehner female (April)

1 twenty-four year old half Cleveland Bay, half Thoroughbred female (Hannah)

1 thirteen year old Connemara gelding (Riley)

1 collar

61 pieces of 1/2 pieces of original Milk Bones medium size

1 three year old mix breed female (Sydney)

1 twelve year old Miniature Pincher male (Elliot)

1 twelve year old Maltese female (Holly)

1 eight year old Cairn Terrier female dog (Flo)

Twenty-four pieces of Bill-Jak chicken flavor treats for cats

1 two year old female mix breed cat (Blacky)

1 fourteen year old male Tabby cat (O_Malley)

1 eleven year old female Calico cat (Mary Catherine)

1 six year old American Shorthair male cat (Timmy)

2 two year old mix breed female cats (Mitsy and Lizzzy)

77 pieces of 2.5 cm long Grimway Farm baby carrots

1 two year old Abyssinian female (Lucky)

1 two year old American male (Chance)

2 two year old Abyssinian/American female (Sweety and Squirrely)

1 one and a half year old American female (Honey)

1. Drill two holes in the center of each block.

2. Secure the light bases onto the block by twisting the twister ties around the base and pushing the ends through the holes. Twist the ties securely under the block.

3. Match the intensities of the lights. Use the Nikon camera_s light meter to match intensities. (If a light bulb ever burns out, then make sure the new intensities match).

4. Choose a spot for the experiment. There should be no distractions, and it should be a place the animal is comfortable in. All other lighting should be neutral.

5. Position the lights. The lights should be placed on either the ground, a stand, or held, so that they are as close as possible to the animal_s eye level. The red and blue lights should be 100 cm apart for horses. For dogs and cats, the lights should be one meter apart; and for guinea pigs, there should be 30 cm between the two lights. The red light should always be to the animals left during training.

1. Get to know the animals. Make sure the animals seem comfortable around you.

2. Hold the animal in place. Have a helper hold the animal using a lead rope clipped to the halter on a horse, a leash on the dog_s collar. Use a collar or hold the cat in place, and hold the guinea pigs in place. The animals should approach the lights as follows: horses should be about 60 cm away, dogs should be 3 meters, cats one meter, and guinea pigs 30 cm.

3. To train guinea pigs cut some carrot peels. Arrange them in a chain going from the animal to the red light. For cats, wait until the animal has its attention on you. Then place a treat in front of the red light. Lead the dog up to the red light, and then reward accordingly. For horses, lead them up to the correct light and then wait until they sniff the light before rewarding them with a carrot placed in a pie tin.

4. Repeat step three (above) until the animal walks to the light without help. Make sure the animal understands what you want it to do before you start to test.

1. Switch the position of the lights without the animal seeing the light switch. The blue light should be exactly where the red light was before.

2. Hold the animal. This time before releasing, hold the animal in place. For cats, dogs, and horses, tap or point to each light, so that the animal notices both lights. For guinea pigs, lift up the animal and hold it in front of each light in turn, for about three seconds. Then return it to the starting position.

3. Release the animal. For horses, walk in front of the animal, and then when you reach the lights, duck down. For cats and guinea pigs, simply let go of the animal and back away. For dogs, let the leash run through your hands, while keeping a firm grip on the end.

4. Wait for their response. Wait until the animal moves toward either light. Do not try to force them to go. Do not give any kind of signal towards one of the lights.

5. Respond to their choice. If the animal walked up to the red light then give them a large treat. Horses would receive an 8 cm carrot, dogs 1/2 of a Milk Bone, cats a full piece of Bill Jack, and guinea pigs a 2.5 cm long baby carrot. Also pat them and say good job. If they walk to the blue light, then give them nothing. Do not call them bad or touch them. As the animal is eating, turn off the light that they did not walk to. If the animal walks to you, do nothing until they clearly choose a light.

6. Repeat the test. If you feel that the animal does not understand what you want it to do, or there was a large amount of time since you last tested the animal and they forgot, you may go back to training.

7. Record data on data sheet.

Lucky: The first animal that I worked on is Lucky, my two year old Abyssinian female, guinea pig. During Lucky_s earlier training sessions, I changed my method from no chain, to a chain of carrot peelings leading to the red light. Before I did this, Lucky would just sit there. I did eight training sessions with Lucky before she stopped. She went to the red light four times, went to the blue once, and went nowhere three times.

Chance: The second guinea pig I did is my two year old American boar (male) guinea pig. We used the carrot chain this time, and Chance walked to the red light four times. The last time he sat still, so I stopped.

Sweety: Sweety is a two year old Abyssinian and American mix sow. I only used the chain leading to the red light four times on Sweety. The next four times, without the chain, she also went to the red.

Squirrely: Squirrely is also a two year old Abyssinian and American mix sow. I used the chain for four of the times, all red. Then I did it seven other times without the chain, of which Squirrely went five times to the red light and only once to the blue.

Lucky: I used the chain five more times today, and Lucky went to the red all of those but once. When I removed the chain for the last three runs, she went to the blue twice and the red once.

Chance: I used a chain for the four times I did my training; all of them were red. Chance seemed to be a little hesitant then.

Sweety: I used the chain for four times in the beginning, the last four were without the chain. All eight were red.

Squirrely: I used the chain for Squirrely_s first two runs, but removed it for the last four. Squirrely went to the red every time except for the last where she went nowhere. Squirrely tells me very simply when she is done, by turning around, and facing away from the lights.

Elliot: Elliot is a male, twelve year old Miniature Pincher. I did twenty training sessions on Elliot, of which all but one were red. In that one, I didn_t use a leash and Elliot chose to go nowhere.

Lucky: I started Lucky out with a chain for the first one of six, all of which were red.

Chance: Chance went nowhere for his first training run, so I added a chain. He used it for the first of six runs, all red.

Sweety: I did four training runs on Sweety, all of which were red, and then decided to test. I did a total of five tests on her, and all were blue.

Squirrely: I started Squirrely out with four training runs, all of which were solidly red, and then moved to testing. I tested Squirrely seven times. Out of those seven, three were red, three were blue, and one was nowhere.

Blacky: Blacky is a female, two year old cat. I started out with training her. I did three all red runs before she tired.

Flo: Flo is a female, twelve year old Cairn terrier. Out of the fifteen training runs I ran, Flo got them all correct with help. However, I do not think she understands what she is doing, because she is too excited.

Lucky: This session, I started with three training runs (all red), and then moved on to testing. I did three rounds, two of which were blue, and one was nowhere.

Chance: Chance did three more strictly red training sessions and then moved on to the test. I did three test rounds on Chance, and while they all were blue, Chance seemed very unsure, and hesitated long before he chose a light.

Honey: I did twelve training sessions on Honey, a half year old American, female guinea pig. All were red with a chain. I_m not including Honey_s results, or working on training longer because she was too confused.

Lucky: Since I have not done Lucky for a while, I_m started with three training sessions, and the results were all red. The results of the four tests I did following the training were two red and two blue, but each time Lucky hesitated.

Chance: I did five training runs on Chance, and they were all red, with the exception of the last one which was nowhere.

Sweety: Sweety did five trainings, all red, and four tests. The results of the tests were two red, one blue, and nowhere.

Squirrely: I did two training runs (red) on Squirrely, and then started to test. Squirrely_s response to the four tests I did was two red, one blue, and nowhere.

Molly: Molly is a female year old golden retriever. I did twenty-seven training sessions on Molly. The twenty five that I used a leash on, were red, but the two where she had control were blue. Molly was getting confused because she associated her leash with walks, and would often head to the door. I will not test her further.

Sydney: Sydney is a female mix-breed dog. Sydney is very smart, and quick to learn. For example, we taught her a trick that was supposed to take weeks to learn, and Sydney learned it in a day. We did twenty training runs on Sydney, of which all were red but one. We then tested her thirty-five times, switching every once in a while. Over the course of these test runs, she would really know what to do. She would stop and wait until the leash was released, walk to a light, sit down in front of it, rest her paw next to it, get her treat, (if any), then walk around me in a circle, and go to where she started. The results of the thirty-five tests is that thirty-four of those times she went to the left, and once she went to the right.

Sydney: I did three training rounds for Sydney to start; all were red. I followed this up with fifty-six test rounds. The results of the tests were that every single time she went to the left.

Blacky: I did five more training runs on Blacky. The first one was blue, and the last one was red.

Timmy: Timmy did eight training runs with help, and consistently went to the red except for the last time when he went nowhere.

Lucky: Lucky did six training runs, all of them were red.

Chance: Chance did two training runs (red), and then did eleven test runs. The results are three reds, and seven blues. The last time Chance went nowhere. A number of the times Chance hesitated, showing his confusion.

Sweety: Because of Sweety_s hesitation, the last time I worked on her, I trained her more. The five training sessions were all red.

Squirrely: After two all-red training runs, Squirrely went to the red three out of the six times I tested her, and also went to blue twice, and the last time went nowhere

Holly: Holly is a female, year old Maltese dog. She started out with twenty-five training sessions, of which all were red in response. Then I tested her thirty two times, and all of them but one were to the left side.

Timmy: I helped Timmy out with the first three of ten eight training sessions (all red). I then tested him twice and the results were solidly blue.

Lucky: Lucky started with three red training runs, and then did fifteen tests. The interesting results were ten trips to the red, four trips to the blue, and one trip nowhere. The first four Lucky hesitated on.

Sweety: Sweety did five test runs after three all red training sessions. The results are four blue responses and one nowhere.

Squirrely: Squirrely did fifteen test sessions, of which twelve were red, and two were blue. The remaining one was nowhere. I switched the light position twice.

Timmy: I trained Timmy four more all red tests, and then moved on to two tests, of which Timmy went to the red each time.

Mary Catherine: Mary Catherine is an eleven year old calico, female cat. I helped Mary Catherine go to the red light three times in the three training runs I did.

O_Malley: O_Malley is a twelve year old tabby, male cat. I helped him go to the red light four times.

Lucky: I worked on Lucky twice this day. The first time I tested her thirteen times, with results of eight red responses, four blue responses, and one nowhere. I switched the position of the lights, after the seventh round. The second time I worked on her, she did sixteen tests, of which fourteen were red, and two were blue. The light position was switched halfway through.

Squirrely: Squirrely went to the red seven out of the fifteen test runs. She went to the blue seven times also, and went nowhere once. The light position was switched half way through.

Timmy: Today I did twelve tests, and Timmy went to the red light eight times, and four blue lights. The light was switched half way through.

Mary Catherine: I helped Mary Catherine go to the red light five times.

O_Malley: O_Malley went to the red light nine times during my nine training runs. Half way through I stopped helping him.

Lucky: Out of the nine tests Lucky did, every single one was red. The light position was switched half way through.

Squirrely: Out of the seven times Squirrely tested today, the first five of them were red, and

then the switch was made, and the last two tests were blue.

Mitsy: Mitsy only did two training runs with help before she decided she was full, and during those two tests she always went to the red.

Lizzy: Lizzy did four training sessions with help. Everytime was red.

Timmy: Out of the ten tests Timmy did today, six were blue, and four were red.

Flo: Flo went to the red for the thirty-four training sessions I did, but she needed help. She is much calmer, but as she hasn_t learned it in thirty-four trails, I will not go further.

Mary Catherine: Mary Catherine only did three training runs before tiring. All were red, but with help. I will not test farther.

O_Malley: O_Malley responded correctly during my four training runs, so I switched the lights and did ten test runs. Out of those, six were red, and four were blue.

Shamus: Shamus, a twelve year old Thoroughbred gelding gave me interesting results. Since he was the first horse that I did, we adapted my test as we went along. We started out by having me hold a light, and having my helper hold the other. Since I was holding the red light, and we altered the project so that the blue light had no treat, I was always giving the treat. We soon realized that he was going to me, not the color of the light. We then changed the test so that my helper would hold both lights eighteen inches apart, and I would stand directly behind her, so I would come out with the treat when needed. Shamus went to the left only three times, and the other nineteen times he went to the right, no matter what color light was there.

April: April is an eight year old Trakehner mare. Some interesting points came up during April_s training, too. April would always walk to the light farthest from her master, thereby respecting her master_s space. Hence, she was not freely choosing a light. We eliminated this by having the master walk in front of the horse, and then crouching down in front of the light. April is the only horse who had a problem with this. April also was timid at first, but gave us interesting results after she got over her fear by sniffing the lights a few times. April got bored early, but when she was still working she went to the red light twelve times and went to the blue light only six times. I noticed that when she hurried to get her carrot, she would tend to not think and go the blue, but when she walked slower she would go to the red.

Hannah: Hannah is a twenty-four year old half Cleveland Bay, half Thoroughbred mare. Even though she is older, her eyesight is great. The only impact her age had on my test, is that towards the end she would often almost fall asleep before picking a light. One of the most interesting things about Hannah is that she seemed to think more. Especially when the lights were changed, Hannah would walk up to them and stop about a foot away. Keeping her head in the middle she would stand there, and think about which light has the treat. Then after her decision was made she would reach her head forward and touch the light with her nose. April did this too. Hannah went to the red light nineteen times and only went to the blue one nine times.

Riley, a thirteen year old Connamara horse gave the best results. Riley_s owner told us before that Riley was smart, and on her first day in a new barn, had learned how to open the gate. Riley would think just like Hannah. After standing and thinking, she would touch the correct light with her nose. Riley choose the red light twenty times and never choose the blue, except once when we felt she was distracted by someone walking by.

To conclude this project I will begin by summarizing each animal_s responses. Sydney, the dog, went to the left ninety times, and went to the right only once, irrespective of how the colors were switched. I think that Sydney thought she was supposed to go to the left because she couldn_t see the colors, so she didn_t know to go to the red. I came to this conclusion on Sydney due to the fact that we did train Sydney twice, so if she didn_t understand the correct response the first time, she would have picked it up the second training session. Holly, another dog, went to the left thirty-two times, and went to the right only once, leading me to believe that she too cannot see colors. My overall conclusion on dogs is that based on the data and what I just noted in the last sentences, dogs cannot differentiate between blue and red lights. This agrees with the majority of the books.

Since the results for Timmy, the cat, were fourteen trips to the red, and eleven times to the blue, my conclusion would be that he can see the lightest tints of some colors, and when he really concentrated he would pick the correct light. If he was truly color blind, then his results would have looked more like the dogs. The results for O_Malley, another cat, were similar to Timmy_s. I believe that O_Malley_s results were more credible, because O_Malley was slower and more thoughtful during the testing then Timmy, and his results of ten red responses and five blue responses were closer to favoring the red light. My overall conclusion on cats is that, they can see faint tints of colors. This conclusion agrees with some of my sources in my research.

Lucky, the guinea pig_s, results of forty reds and fifteen blues leads my to believe that she can see colors. Some of the blues were in the first tests, but when I started training her more she improved in her responses. I think that doing an extra training round helped to emphasize that color is what she is to respond to, not the location. Lucky is a smart guinea pig and knows lots of tricks, so that strengthens my assumption that she knows what she is doing, not randomly guessing. The results for Chance, another guinea pig, of three red and thirteen blues leads me to a very interesting conclusion. The first is that Chance might prefer blue over red. Guinea pigs do have favorite objects, treats, and friends. What really leads me to believe this is that even when the lights were switched, Chance would switch too. If Chance could not see colors, then he would not switch. The third guinea pig, Sweety_s results of two to the red and five to the blue leads me to believe that either she doesn_t see color, or she didn_t understand what she was supposed to respond to. I think that the last test had more credit to it, due to the fact that Sweety switched to red for the last two, as if she started to understand. The final guinea pig, Squirrely_s results of thirty-two times to the red and seventeen times to the blue leads me to think that guinea pigs can see color. Even though she did go to the blue seventeen times, I think that Squirrely did that because she would tend to run to the light the second she was released and so sometimes she would go to the blue before noticing they were changed. Then she would switch to the red. My overall conclusion is that because most of them seemed like they could see color, I concluded that yes, guinea pigs can see color. This agrees with the two sources I was able to find.

Shamus, the first horse tested, went to the left nineteen times, and went to the right three times. My conclusion on Shamus is that either he can_t see colors, or he misunderstood what was being asked of him. I lean more to the last conclusion based on the fact that all the other horses could see colors. Also he was the first horse I did so I was improving my test as I went along to remove variables, and that could have confused him. April, the second horse, went to the red twelve times, and went to the blue six times. Whether she can or can_t see colors is not real clear in these results, but I would most likely conclude that she can see color. I noticed that for the times she went to the blue, she was walking faster then when she went to the red. Therefore, if she slowed down and looked at the lights as she walked, she would respond correctly. Hannah went to the red nineteen times, and went to the blue only nine times. This makes me think that she can see color, especially since most of the blues were toward the end when she was getting tired. Riley, the last horse tested, went to the red twenty times and never went to the blue. This make me very sure that he can see colors. It could be possible that he was noticing our reactions to him, just like the circus horses I wrote about in my paper, but I dismissed this idea for several reasons. First, we were not doing anything very noticeable, so he would have to be very well trained to pick up those little details, and he was not trained. Second, he would stop a foot away and then he would wait, and think. If he was cueing off of us, then he would not wait, for the longer he waited the more relaxed we would be and therefore the less cues. Because of that I concluded that Riley does see colors. My overall conclusion on horses is that they do see colors. This agrees with the scientific research at the University of Western Ontario.

My overall conclusion is that horses can differentiate between red and blue lights the best because not only did all but one of them perform correctly, one of them was perfect every time. The next best animals were the guinea pigs. They were correct most of the time, but they didn_t have as large of a percentage as the horses. Second to last is the cats. They really didn_t go to the red light enough to say they could see colors. Last were dogs. They showed quite clearly that they can_t see colors. The results were different than my hypothesis which ranked their ability to see colors as follows: guinea pigs, then horses, then dogs, and last cats.

Alderton, David.(1983). The cat. New Jersy: Chartwell Books, Inc.

Altman, Dietrich. (1997). Starting with guinea pigs. New York: Sterling Publishing Co.

Barrie, Anmarie. (1994). A step by step book about guinea pigs. Lanham: T.F.H. Puplications.

Bordwell, Sally. (1994). Dog health and care. New York: Hearst Books.

Budiansky,Stephen. (1997). The nature of horses. New York: The Free Press.

Carlson, Dilbert G.D.V.M., & Giffin, James M.M.D. (1992). Dog owners home vetinary handbook. New York: Howell Book House.

Case, Linda P. (1999). The dog. Ames: Iowa State University Press.

Chapple, Judy. (1987). Your horse. Vermont: Garden Way Publishing

Clutton-Brock, Juliet. (1991). Eyewitness books cats. New York: Alfred A.Knopf.

Copper, Gale M.D., & Schiller, Alan L. M.D. (1975). The anatomy of the guinea pig. Cambridge, MA: Harvard University Press.

Coren, Stanley. (1994). The intelligence of dogs. New York: The Free Press.

Curran, Wanda L. (1995). Your guinea pig. Vermont: Stoney Communications.

Downers Grove Vets. (1999). Care of guinea pigs. Pamphlet.

Edwards, Hartley E. (1991). The ultimate horse book. New York: Dorling Kindersley.

Evans, Mark. (1992). ASPCA pet care guides for kids guinea pigs. New York: Dorling Kindersley.

Flade, Johannes E. (1987). The compleat horse. New York: Prentice Hall Press.

Fogle, Bruce D.V.M. (1997). The encyclopedia of the cat (Volume 1, The senses). New York: OK Publishing.

Gurney, Peter. (October 19, 1999) Re: color perception in guinea pigs [Online]. Available email: jmdebruler@chicago.avenew.com from pggps.gurney@virgin.net.

Kelsey-Word, Dennis. (April 30, 1999). Health problems. Guiena pigs today, p. 32.

McBane, Susan, & Douglas-Cooper, Helan. (1991). Horse facts. New York: Dorset Press.

Martinello, Marian L. (1998). "Spring Break" Page 2. [Online]. Equibas Company. Available: http://www.readylady.com/springbreak_folder/springbreak2.html. [Dec. 6, 1999].

Mills, Bruce, & Carne, Barbara. (1998). A basic guide to horse care and management. New York: Howell Book House.

Morris, Desmond. (1997). Cat world. New York: Penguin Reference.

Nelson, Stephen. (1995). Guinea pig as a new pet. New York: T.F.H Publications.

Pavia, Audrey. (1997). The guinea pig. New York: Howell Book House.

Probst, Sarah. (June 15, 1998) Through the eyes of your canine. [Online]. University of Illinois, College of Veterinary Medicine. Available: http://www.cvm.uiuc.edu/ceps/PetColumns/hameye.htm. [Dec. 6, 1999].

Ritter, William. (1982). The T.F.H. book of guinea pigs. New York: T.F.H Publications.

Rutherford, Alice Philomena. (1992). The Reader_s Digest illustrated book of cats. New York: Reader_s Digest Association.

Seddon, Tony. (1988). Animal vision. New York: Facts on File.

Sinclair, Sandra. (1992). Extraordinary eyes. New York: Dial Books.

Sinclair, Sandra. (1985). How animals see. New York: Facts on File Publications.

Smith, Carina A.P.V.M (1991). Easy health care for your horse. New York: Prentice Hall Press Equestrian Books.

Steinkamp, Anja J. (1996). Your first guinea pig. New York: T.F.H. Publications.

Stoneridge, M.A. (1990). A horse of your own. New York: Double Day.

Sullivan, Mary Ellen. (1999). Cows on parade in Chicago. Kreuzlingen, Switzerland: Neptun Verlagsauslieferung AG.

Sylvester, Patrica. (1993). The Reader_s Digest illustrated book of dogs. New York: Reader_s Digest Association.

Timney, Brian, PhD. (April, 1998). What Horses See. Equus, Issue 246, pp. 28-36.

Vernot, Jackie. (October 15, 1999). Telephone interview.

Vogel, Colin. (1995). The complete horse care manual. New York: Darling Kindersley Publishing.

Wessner, Cecilia (Nov., 1999) How do scientists know that dogs are colorblind? For Your Information. Popular Science, p. 101.

Ziesmann, Jurgen. (July 17, 1998). Re: What animals can see in color? How is it determined? [Online]. The MAD scientist network. Available: http://www.madsci.org/posts/archives/oct98/905228364.Zo.r.html [1999, Sep. 25