Everything that we see around us is the illusion only. What we see around us is actually not the way they are in reality. For us, the sky appears flat to us, the sun seems to move across the sky to us. All these are nothing but the optical illusions which our eyes have created. Generally Optical illusions can be attributed to the visual perceptions of ours or the intellectual interpretations of ours. According to the study the past experiences of a person, the desires and the influences from different persons or events are also responsible for the creation of the optical illusions.
Due to erroneous vision or mistaken judgments the visual illusions may take place. When there is an error in estimating the distance of an object and the viewer it is an example of judgment. Sometimes, a bright object appears larger than a dark object even if the dimensions are the same. When the objects having the contrasting colors are kept closer, one may mistake one color for the other. It is an error which happens during sensing the object. Our brain has the tendency to group things into four different types which are similarity, continuity, closer and proximity. The similar color objects are grouped together to get a particular shape. Our brain always searches for patterns. The brain tries to find the continuity in whatever it sees. When short lines kept at space are arranged in a circular way the brain perceive it as a circle. The objects kept closely are grouped together. One of the natural phenomena which is commonly talked about or can be seen in the nature is the formation of mirage. In case of mirage the light rays coming from an object bend and the object appears in a place where it is not exactly present. For some there seems to be no difference between the hallucination and optical illusion but there is a very minute different between the two. In case of hallucination, an object appears though it is not there and it is more of an individual’s experience.
According to Wundt, the laws which deal with the formation of retinal image and the eye movement are responsible for the optical illusions. When the light falls on an object ,the light gets reflected by the object and an inverted image of the object gets created on the retina in the eye. The brain then interprets the image and then we are able to perceive the object the way it is really present. When the perception does not match with the actual physical dimensions of the object , it is considered as the optical illusion. When a flat surface is represented by a shade of colors, it seems to be very deep. When an object has some specific geometrical structures these create an illusive effect on the viewer. When the eyes are raised in a horizontal plane, the effort involved is more than that of the effort needed to turn the eyes. This difference of effort makes the eyes to feel that the vertical distances are greater than that of horizontal one of the same magnitudes. The involuntary movements of the eyes cause angular movements.
The chromatic and spherical aberrations are caused by the lenses. Eyes have abnormalities such as eccentricity and astigmatism. All these aberrations or abnormalities lead to optical illusions. The wave lengths of different colors vary so their angle of reflection and refraction also vary. Due to these differences chromatic aberrations happen and as a result optical illusions like “advancing” or “Retiring” colors are caused. When one keeps the eyelids almost closed, because of the movement of the eyelids, objects seem to be moving. When one eye is closed, the distance and direction of an object cannot be judged accurately. The distance and direction of objects seem to vary depending on the concentration of the objects placed in the area. If a line is divided into smaller partitions then the partitions seem to appear shorter than a single line of the similar length as the partition. We can conclude by saying that optical illusion works based on the principles of light and the how the light is interpreted by the eyes.