However, we can be deceived by our senses. For example, optical illusions - A visually perceived image that is deceptive or misleading. Take figure one as an example – the two circles in the middle are placed next to each other and one is surrounded by large circles while the other is surrounded by small circles. The first central circle appears bigger than the second central circle, but they have identical sizes.
Also, our sensorial perception can sometimes be altered by environmental, emotional, or physical factors such as stress, medication, extreme fatigue, extreme temperatures and many others. For example, some people claim that they have seen oasis in the desert, but what most of these people experience is a hallucination – “hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid, substantial, and located in external objective space” - due to the extreme heat, that affects their ability to perceive the reality of the situation i.e. the inexistence of an oasis.
There is also the fact that sense organs are unique and characteristic in different species. For example, dogs have a very good sense of smell, whereas their sight is not as developed as humans’. If dogs don’t rely mostly on their vision, unlike humans, this means that they have a different perception of the world. Similar situations occur without moving away from the ‘human world’ – as a person loses a sense, another sense tends to over-develop, as in the case of blind people which tend to develop the ability of hearing. So, not only is their world different because they can not see, but because their ability to hear is more developed than the one of any ordinary person. Therefore, it can be argued that as we interpret what we perceive, using our sensorial perception, we create our own reality, which can never be said to be an absolute vision of reality.
Also, perception is selective: we don’t – and can’t – be aware of everything that is happening in a given situation. As human beings, we don’t hear every existing sound, we don’t see every person in an area, and we don’t notice everything that occurs in a given environment... If our sense organs were not selective during the perception of things, our reality would be nothing alike to what it is today.
Furthermore, if a sense is a "a system that consists of a group of sensory cell types that responds to a specific physical phenomenon, and that corresponds to a particular group of regions within the brain where the are received and interpreted.”, then each time we perceive something through our sense-organs we automatically interpret it. As human beings it is almost impossible to stop ourselves from including our values and judgements in our interpretations. Therefore, it can be said that our perception of the world depends, not only upon our senses, but also upon our culture, values, beliefs and personal opinions. So, for example, some people believe that the death penalty is right and fair as those who commit severe crimes ( such as murder or rape) deserve to be killed, while some (e.g. most Christians) believe that it is wrong and that it only encourages and contributes to a violence vicious cycle. The same occurs for abortion – some people believe that abortion should be allowed, as it is a personal choice to terminate a pregnancy- , while others see it as murder. Also, different people interpret messages in films/books/etc differently, according to their beliefs and awareness. So, if different people have different perceptions of the same situations, it can be argued that perception is not 100% reliable.
To conclude, perception is a vital source of knowledge and it is essential for our daily survival. However, we cannot simply take the evidence perceived by our senses for granted – not only because we can be deceived and misguided by them (optical illusions, hallucinations, …), but also because our senses are highly selective and our perception is distorted by our beliefs and opinions. So, if our perception of the world and of the vision of reality is mainly composed by our selective and distorted perception, this means that our world is composed by what we, unconsciously, chose it to be composed of, if our vision of reality is composed by what we unconsciously want to perceive as being real according to our beliefs, and if our senses can ultimately be deceived then we can’t always trust our own perception of things, as it will never be an absolute and impartial analysis of information perceived by our senses.
