Our day to day experience of reality and the world around us happens through our senses.
A sense is a faculty by which outside stimuli are perceived by the brain, each sense, therefore, can differ from human to human depending on how one's brain interprets said stimuli.
Our human senses are split into two different groups.
Our exteroceptors detect stimulation from the outsides of our body. For example smell & taste. The interoceptors receive stimulation from inside our bodies. For instance, blood pressure.
While we are taught there are five exteroceptor senses (sight, hearing, touch, smell, taste) and no one doubts these, having been classified since the days of Aristotle. Other researchers argue that "true senses are bodily systems consisting of a group of sensory cell types that not only respond to a specific physical phenomenon but also correspond to a particular region in the brain." (Cerretani, 2014)
From Harvard Medical School researchers to neurologists, most recognise additional human senses, however, ask how many senses humans have and you’re bound to receive a range of answers. For now, we’ll have to continue to rely on our five standard-issue senses.
Taste and Smell; are clasified as chemical senses because the receptors they contain are sensitive to the molecules in the food we eat, along with the air we breathe.
Vision needs both the eyes and the brain to process any information. The majority of the stimuli is done in the eyes and then the information is sent to the brain (often the cerebral cortex) by the way of nerve impulses.
Hearing; the ear is the sense organ that collects and detects sound waves and plays a major role in the sense of balance and body position. The sensory receptors are hair cells that are extremely sensitive to mechanical stimulations.
Touch is the first sense developed in the womb and the last sense used before death. The skin is the largest and one of the most complex organs in our bodies. With 50 touch receptors for every square centimetre and about 5 million sensory cells overall.
So for humans, our sense of vision largely dictates how we perceive the environment around us, unlike most other mammals who's sense of smell dominates their world. Vision is also the most well-developed sense in humans, in terms of complexity, the amount of brain area used, and advancement over other mammals. (King, 2012) Alongside vision's dominance smell is key and plays a large "role in social communication, detecting emotional stress in others (‘emotional contagion’) and of course during eating." (Curnoe, 2015)
Senses are a balance between the brain (neurological) and the body (psychological) if this becomes unbalanced or damaged, "some phenomena like synaesthesia and referred pain can cause a 'confusion' of our processing or understanding of input."(Muniz, 2015)
"Synaesthesia is a condition where a sensation in one of the senses, such as hearing, triggers a sensation in another, such as taste. For example, some people with synaesthesia can taste numbers or hear colours."
It is also interesting to consider what would happen should all input signals were to a suddenly cese. "We would still have the memory of their functionality, and ... because our imagination is the conscious experience of these senses and their actual functionality or employment is not necessary for us to perceive the experience of using them." (Muniz, 2015)
Cerretani, J. (2014) Harvard medicine. Available at: http://hms.harvard.edu/news/harvard-medicine/extra-sensory-perceptions (Accessed: 5 July 2016).
Human physiology/senses - Wikibooks, open books for an open world (no date) Available at: https://en.wikibooks.org/wiki/Human_Physiology/Senses (Accessed: 5 July 2016).
King, P. (2012) Which one of our five senses is best developed? Available at: https://www.quora.com/Which-one-of-our-five-senses-is-best-developed (Accessed: 5 July 2016).
Curnoe, D. (2015) Making sense of our evolution. Available at: http://theconversation.com/making-sense-of-our-evolution-44591 (Accessed: 5 July 2016).
Muniz, D. (2015) What would happen to/in our brain if we lost all five senses at once? Available at: https://www.quora.com/What-would-happen-to-in-our-brain-if-we-lost-all-five-senses-at-once (Accessed: 5 July 2016).