What is an optical illusion?
104076
An optical illusion is when your mind perceives and interprets visuals differently. Basically, people call it a flaw of the visual system but basically it means that you are just experiencing and sensing things that are clear to you in a different way. It happens to everyone, and usually happens when you are not looking closely... \n\nWanna try a really cool optical illusion? Try this one:\nhttp://www.brainteasercentral.com/riddle.php?riddleid=680&PHPSESSID=c0b73d7cde4995835be4fad0b5d3152b\n\nFollow the instructions on the page and see what happens. I bet you'll be shocked. =p\n\nMore info on optical illusion here: http://www.michaelbach.de/ot/
1132483
their is one in (north burlington ontario) as well  .I have also read their is one in  Oshawa ,ontario, If you go to the bottom and place your car in neutral it drags your car uphil slowly .\n____________________________________________\nscientifically it is an optical illusion \nSometimes you may find or hear of a mysterious place where objects can apparently roll uphill. This is a remarkably common illusion which is found in numerous locations around the world. Usually it is a stretch of road in a hilly area where the level horizon is obscured. Objects such as trees and walls which normally provide visual clues to the true vertical, may be leaning slightly. This creates an optical illusion making a slight downhill look like an uphill slope. Objects may appear to roll uphill. \nSpots where the illusion is especially powerful often become tourist attractions. Tour guides may like to claim that the effect is a mystery or that it is due to magnetic or gravitational irregularities or even that it is a paranormal phenomenon which science can not explain. This is not true of course. Natural irregularities can only be detected with sensitive equipment and cannot account for these places but science can easily explain them as optical illusions. \n\nThere are several things which enable us to sense which way is up. The balance mechanism in our inner ears is one system we have, but visual clues are also important and can be overriding. If the horizon cannot be seen or is not level then we may be fooled by objects which we expect to be vertical but which aren't really. \nPeople often overestimate the angle of a slope. If you are standing on a slope of 1 degrees it will seem like a slope of 5 degrees. Because of this effect the anti-gravity illusion can seem stronger than it should be even when you know the cause.\n\nEven when the true cause is understood it can be difficult to believe. If you think there is a magnetic anomaly just use two plumb lines, one made of iron and one of stone. They would hang at different angles if a strong magnetic field was acting horizontally. \nHowever, it is not always easy to demonstrate that a slope which appears to go uphill is really going downhill. The only reliable way of determining the true horizontal is by careful surveying. If a good topographical map of the area is available it may be sufficient to show which way the land is really sloping. The results will confirm the illusion. \n...\nyou can also check the info I found on the Oshawa site \nhttp://www.shopinoshawa.com/magnetichill.htm
1168605
An hallucination is a sensory perception experienced in the absence of an external stimulus, as distinct from an illusion, which is a misperception of an external stimulus. Hallucinations may occur in any sensory modality - visual, auditory, olfactory, gustatory, tactile, or proprioception (sense of balance and position in space).
888651
Been a few years since I have been there and it was great fun. I had a Blind friend with me and he was not affected. He let me know right away that there was a tilt to the house.\n\nI proceeded to tell him about the optical illusions I was experiencing so he could enjoy it with me. The tilting creates optical illusions. I also closed my eyes and could really feel the tilt. I found out later, the house is tilted at a 20-degree angle from the ground\n\nEven though I knew the secret, it did not diminish the fun. I know a lot of secrets to illusions of magic and I still enjoy watching them preformed. It is not how it is done that counts, it is how well.
909985
Nothing magically appeared. God created it. Magic is using illusion to mimic powers such as those that only God has....
780246
It is something like solar eclipse.It depends on how close to the eye you hold it.It can be anything total,annular or partial.\nIt will be partial if the axis of the disc deviates slightly from the line of view.
1002589
its the imperfections that make things seem perfect.\nall an illusion
425005
May be a daft suggestion, and I dont know if it would work but - how about sausage tubing, filled with a kapok/plaster mix... that you fill, and then twist and compact into a basin that is roughly brain sized...\n\nAs for illusions affecting the mind...\nit is the mind that creates the illusion... and I cant see there is a problem so long as we know they are illusions. The problem is when we believe the illusion.\n\nSorry... can't help more than that.
1186661
my explanation:\nthe common "desert" mirages like in movies are fueled by human desire. say, you wish you could find an oasis, with maybe a hot chick i mean sauna to help you relax. your mind invisions this and overlays it over the dry, dull, monotonous landscape. you run to go kiss that hot chick i mean open the sauna door, and it is usually empty nothingness. utter hopelessness can also fuel this, making you actually believe a pit of sand is a beautiful spring with that hot girl again i mean sauna sitting at the edge of the spring. \n\nour good friends at Wikipedia say:\nA mirage is a naturally-occurring optical phenomenon, in which light rays are bent to produce a displaced image of distant objects or the sky. The word comes from the Latin mirari, meaning 'to be astonished'. This is the same root as for mirror. Like a mirror, a mirage shows images of things which are elsewhere. The principal physical cause of a mirage, however, is refraction and not reflection.\n\nA mirage is not an optical illusion. It is a real phenomenon, and one can take photographs of it. The interpretation of the image, however, is up to the fantasy of the human mind\n\nCold air is denser than warm air, and has therefore a larger refractive index. As light passes from colder air to warmer air it bends away from the direction of the temperature gradient (the "normal" in the figure at right); when it passes from hotter to colder, it bends towards the direction of the gradient. The diagram on the right shows a light ray coming from the sky toward the hot ground. If the air near the ground is warmer than that higher up, the light ray bends in a concave up trajectory. Once the ray reaches the viewer’s eye, the eye traces it as the line of sight, which is the line tangent to the path the ray takes at the point it reaches the eye. The result is that an inferior image for the above sky appears on the ground. The viewer may incorrectly interpret this sight as water reflecting the sky. In the case where the air near the ground is cooler than that higher up, the light rays will of course curve downwards, producing a superior image.\n\nThe 'rest' state of the Earth's atmosphere is with a vertical gradient of about -1 degree Celsius per 100 metres height. (The value is negative because it gets colder when you go higher.) For an actual mirage to happen, the temperature gradient has to be much greater. According to Minnaert[1] the magnitude of the gradient should be at least 2°C per metre, and the mirage will not get strong until the magnitude reaches 4 or 5°C per metre. These conditions can occur when there is strong heating at ground level, for example when the sun is shining on sand or asphalt.\n\n[edit]\nInferior mirage\nThe model given above explains the cause of the inferior mirage, called inferior because the image seen is under the real object. The real object is the (blue) sky or any distant object in that direction, meaning we see a bright bluish patch on the ground in the distance. For exhausted travellers in the desert it appears as a lake of water. On tarmac roads it may seem that water or even oil has been spilled. This is called a highway mirage or desert mirage. Note that both sand and tarmac can become very hot when exposed to the sun, easily being more than 10°C hotter than the air one centimetre above, enough to cause the mirage.\n\nLight rays coming from a particular distant object all travel through nearly the same air layers and all are bent over about the same amount. Therefore rays coming from the top of the object will come less high than those from the bottom. The image usually is upside down, enhancing the illusion that the sky image seen in the distance is really a water or oil puddle acting as a mirror.\n\nInferior images are not stable. Hot air rises, and cooler air (being more dense) descends, so the layers will mix, giving rise to turbulence. The image will be disformed accordingly. It may
1148084
Its all about illusion and distracting the eye. Our minds are easilly tricked.
146049
My son just did one for 4th grade.  He used Optical Illusions and their perception among age groups.  It turned out really cool.  We copied optical illusions from library books and pasted them up.  Then he made a stop-motion animation move on his computer, and explained how he did it.  He also made flip-books. It was cool.
471698
Perception is how things appear to YOU.
861756
When you look out of the window, you think that you see an image with your eyes, as this is the way that you have been taught to think. However, in reality this is not how it works, because you do not see the world with your eyes. You see the image created in your brains. This is not a prediction, nor a philosophical speculation, but the scientific truth. \n\n     This concept can be better understood when we realize how the visual system operates. The eye is responsible for transforming light into an electric signal by means of the cells in the retina. This electrical signal reaches the sight center in the brain. The signals create the vision you see when you look out of the window. In other words, the sights you see are created in your brain.
1028559
Love is only an illusion if it's one-sided.  If you find someone who loves you as much as you love them, there's no better feeling in the world.  Everyone you meet will be able to see that love between you, and that right there is no illusion.
1026711
There is a physical condition that makes you see odd things, a common one is an object floating in the sky. Try the Fortean website, \nwww.forteantimes.com\n\nA friend of mine sees Bruce Lee, dressed as in Enter the Dragon.
20255
I had always believed that it was the effect of light passing through differing layers of the atmosphere, but on doing a quick search to check my hypothesis, I found an amazing site on "The Moon Illusion" that systematically goes through and discusses an amazing number of different theories (and systematically negates pretty much all of them). Early on in the information, it says, "We know that this phenomenon is not a physical or atmospheric effect..." So much for my assumption!\n\nAfter many pages of discussion, it ends with the following words: The final word has not yet been written on this subject.\n\nYou have to check out this site -- it's pretty amazing.
756730
Yes, those are fun. I love any type of optical illusion.