Optical illusions are enjoyed by many people. Not only are they entertaining, but they also reveal information about the workings of the human eye and brain. These two organs are the most important parts of the human body for processing information. Even people with 20/20 vision and high IQs can be fooled by optical illusions.
Fooling the brain
Negative retinal afterimage can be a positive thing, at least in terms of letting you appreciate optical illusions. According to Professor Michael Bach, this is the name of a process that fools the brain into thinking it's seeing something it's not. It's caused by an adaptation of the photoreceptors in the retina when an individual forces her eyes to fixate on a point for an extended period of time, according to the University of Utah.
Why negative retinal afterimage occurs
Negative retinal afterimage occurs when your retinas are subjected to the same hue for several seconds, because of stimulation of the ganglion cells, according to Bach.
Positive retinal afterimage
There is also a phenomenon called positive retinal afterimage, although scientists don’t understand this so well. An example of positive retinal afterimage is the effect you see when you wave a sparkler through the air, according to ophthalmologist James Ver Hoeve.
Stellar optical illusions
A star constellation is not really a group of stars in the same way that the planets of the solar system are a group. According to University of Wisconsin research fellow Chris Dolan, star constellations are totally imaginary.
The facts about star constellations
Star constellations are groups only in the visual sense, because they create 2-D shapes or signs humans can recognise. In reality, the stars that make them up can be vast distances away from each other, in different parts of the universe.
There are several optical illusions relating to objects that appear to form the characteristics of a face. "The Face on Mars" photograph of the Cydonia region of the planet taken by the American Viking 1 Orbiter on July 1976 seems to show a face on Mars' surface. Humans are good at recognising faces and can see them in unlikely places, such as the fronts of cars. This phenomenon is called pareidolia.
Moon size illusion
The moon size illusion makes the moon look bigger when it's on the horizon than when it's high in the sky. In reality, the moon remains the same size. This optical illusion has been appearing for thousands of years, according to NASA. This optical illusion is not fully understood by scientists, but there are many different hypotheses as to what causes it.
Touching the moon
You can make your own optical illusions using an object that is 384,400 km from Earth. The object is the moon. For example, you can take a photograph of a friend pretending to touch or hold the moon if you frame your shot correctly.
Corpses can create optical illusions
According to author Eric Gryzymokowski, corpses can create an optical illusion. Gryzymokowski challenges the belief that human hair and nails continue to grow after death, claiming it is a myth. In fact, the skin shrivels, creating the appearance of continued hair and nail growth.
Optical illusions can save life
Gryzymokowski also refers to another death-related optical illusion. This one is designed to prevent death and injury in Vancouver, where road bumps have been painted with a 3-D image of a young girl playing with a ball to slow down speeding drivers.
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