We have always ignored the intricacies of human vision and taken vision for granted but there are a number of controversial issues surrounding human vision that should draw curiosity. Just like the other bodily senses, human vision does not call attention to itself in order to work. It is this aspect of vision that has made scientists to work continuously and, in most cases, fruitlessly in a bid to gain an understanding of how vision really works. Among the most mysterious aspects of human vision is the phenomenon of optical illusions in which a person perceives something that is not there from a real-life object. The object/image could be strategically designed to have that effect or the viewer may just misperceive a normal object/image.
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Optical illusions prove to be very resourceful to people who understand them but they can equally be disastrous. They make us fully appreciate the world while appreciating the fact that sometimes they should be avoided. The strange thing is that the audience to which the illusion is being applied to do not actually know that it is misperceiving the reality. This is despite the fact that in some isolated cases, determination of whether a perception is accurate may be possible.
In these cases, a keener look at the object/image may make the viewer determine the authenticity of his/her perception. However, like it has been stated above, most misperceptions appear to be accurate to the viewer and a determination of their accuracy may necessitate a discussion of the image among people with normal eyesight. This interesting phenomenon has attracted substantial research in a bid to explain how it works.
The human visual system
Substantial controversy has, for a long time, ensued about the perceptive component of vision, when a cognitive scientist discovered that human beings have the capability to see events that will happen in the future. The scientist found out that humans were able to glimpse events that would happen in one-tenth of a second. The theory seems impossible and misleading at a glance but a detailed look at the reasoning behind it makes one change his/her position about the theory. The mechanism used to explain this phenomenon has also been used by scientists to, partly, explain how optical illusions occur.
It all starts with a lag in the neurons that occurs when we are awake. After an image of what we are viewing hits the retina in form of light, a delay occurs before the image can be translated into a real world image in the brain. The lag is estimated to be about a tenth of a second. Scientists know about the delay and they have been having contradicting explanations of how we manage to see live objects without delay. The most plausible explanation that has ever been put forward for the same is that our visual system is able to generate images of events that are scheduled to happen in a tenth of a second (Jung, 2005, p. 1). This is of course possible because the brain is part and parcel of our visual system.
The aforementioned ability of the visual system to see into the future is due to a lag in our visual system can be used to demystify the phenomenon of visual illusions. Scientists have discovered that illusions occur when we see an image and our brain attempts to see the future in the image. Illusions are specifically a wrong interpretation of an image and they, therefore, occur when the attempt by the brain to see then future is wrong (Ayoub, 2005, p. 1). That is, the interpretation of the image that the brain forms is different from the actual reality.
The theory explained above is referred to as the foresight theory and it is appropriately used to explain a number of illusions. One of the illusions that the theory is used to explain is the herring illusion. This illusion is characterized by lines that come from a central point like the spokes of a bike. It also has straight lines oriented vertically on the two sides of the central point. The effect of the illusion is that the straight vertical lines appear as if they are curved.
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The explanation to this is the fact that the spike-shaped lines create some kind of a perspective that makes the viewer activates his/her foresight capabilities. The viewer therefore finds his/herself in a position that he/she is moving forwards visually. Since, the viewer is actually static and he/she is not moving, the straight lines appear to be curved. In reality, when one is moving, the shape, angular size, contrast of the object and its background and speed seem to change (Bach, 2010, p. 1). Thus the explanation of the herring illusion is right.
Human beings are able to see due to two-dimensional images formed on their retina by light rays reflected from three-dimensional objects. Any retinal images can possibly be made by a myriad of real-life situations. Scientists have thus been appalled by the possibility of interpreting the vision of a given object in a number of ways (Coren, 2006, p. 1). For instance, a shape of a cloud can be viewed to reflect a resemblance of several real life objects. This subject has therefore attracted a lot of research with scientists trying to unveil the details of how we are able to see and also demystify the phenomenon of visual illusions. Consider the example below.
Given a collection of lines that are equal in length but aligned differently as shown below, the horizontal line will always be viewed to be shorter that its vertical and diagonal counterparts.
This demonstration, therefore, illustrates the fact that we unconsciously add length to lines that are either vertically oriented or inclined at a certain angle, no matter their angle of inclination. This observation is a very good example of how we process visual information. It can also be proven when a person is told to draw a square without using a ruler. If one is told to draw a square without using a ruler, he/she will definitely draw a square that has a shorter height and a longer base. This is because the person drawing will subconsciously reduce the length of the vertical line since in normal circumstances; a vertical line is seen to be longer than a horizontal line of the same length.
Thus a perfect square will always be seen as being taller than its width. As it has been explained, this is because our brains will add length to vertical lines automatically as it processes the lengths of the sides of the square (Bryner, 2008, p. 1). Scientists have had sleepless nights about this phenomenon figuring out the reasons why the brain seems to misperceive the lengths of vertical and horizontal lines, and a myriad of other phenomena.
Reasons for the imperceptions
Optical illusions are not generally physical but it proves a very difficult task to explain what really causes them in some cases. Undoubtedly, some significant errors of judgment may occur before one experience an optical illusion. For instance, if one misperceives the estimate of the distance from a given mountain, this can be deemed as a judgment error (Ackerman, 2003, p. 1). In other cases, other forms of errors can be appropriately used to explain misperceptions. For instance, if a white paper is placed on a pink background and a person perceives it as being pink, this can be appropriately termed as an error of sense.
It can be realized from the above cases that questions in psychology are bound to arise when one attempts to explain misperceptions in this perspective. The visual sense delivers specific data that can not solely translate to image perception. This data includes, light, color, intensity of color and light, direction, etc. These are taken to be sensations that are so basic that their analysis will prove to be challenging.
A further discussion of this section would lead to many details of the controversial psychology that surrounds the visual perception of images and objects but basically, the physical sensations do not have much to do with optical illusions. The most common perspective that is used to explain the occurrence of misperceptions and the resultant optical illusions is an evaluation of the intellectual component of human visual system.
Although the optical structure of the eye is at times responsible for optical illusions, most optical illusions are caused by the dynamism that is associable with the human intellect. This is to say that most optical illusions are related to the human intellect, a subset of the visual system in human beings. With this information, it is apparent that the actual image formed on the retina from the object contributes an, arguably, small percentage to our perception of the image (Bach, 2010, p. 1). Thus our perceptions may turn out to be inadequate in one way or another but the good thing is that they are mostly satisfactory in a pragmatic sense. It is this fact, that most of the perception is determined from within, which makes optical illusions a common phenomenon.
Our visual system has a lot of visual information to process in our lifetimes. The world is full of physical objects that are very different in orientation, shape, location, size, etc. It is thus impossible for any single description of a visual system to fit all these objects and how they are processed by the visual system. With this kind of enormous information to process, it is logical, and research has shown, that the visual system depends heavily on probabilistic approaches when processing visual information. This means that once the image of a real-life three-dimensional object is formed on the retina, the brain has a number of interpretation options to choose from.
It, therefore, subconsciously processes the various options of interpretation and chooses the image interpretation that seems to be more probable than the others based on the experiences that the individual viewing the object has had in the past (Ackerman, 2003, p. 1). With this reasoning, therefore, optical illusions occur when the most probable interpretation of the image that the brain chooses is actually different from the real object that forms the image on the retina of the viewer.
As it has been evidenced in the discussion above, there are a number of real life objects and/or images that are bound to attract misperceptions as far as human vision is concerned. These objects/images attract misperceptions due to the fact that the brain is a central component of the human visual system and its processing of images is highly depended on past experiences of the viewer. Optical illusions have been defined as a product of the aforementioned imperceptions in which a viewer perceives an image that is not actually there based on the visual experiences he/she has had in the past.
The numeracy of optical illusions has, for a long time, challenged scientists. They may be beneficial to an individual or even dangerous or disastrous depending on their application. Optical illusions have, for a long time, been used by artists to create certain impressions depending on the intentions of the artist. Architects or painters may use or avoid to use them depending on the effects that they may have on their work.
Illusions have also been widely used by stage artists to make the audience imaginative. Magicians and acrobats have also widely applied optical illusions in their work to create specific impressions on their audiences. Illusions may also have devastating effects like in cases where a person misjudges the distance between him/her and an approaching object like a vehicle for obvious reasons.
Ackerman, S. (2003). Optical Illusions: Why do we see the way we do? Web.
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Ayoub, C. (2005).Optical Illusions. Web.
Bach, M. (2010). 88 Visual Phenomenon & Optical Illusions. Web.
Bryner, J. (2008). Key to all Optical Illusions Discovered. Web.
Coren, S. (2006). Optical illusions. Web.
Jung, C. (2005). Optical Illusions are Everywhere. Web.