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I’ve been always interested in sensory hypersensitivity, but in the past I limited my research with eight senses (vision, hearing, tactility, olfaction, gustation, proprioception, interoception and vestibular system). However, I’ve met a few individuals (on the autism spectrum) whose experiences made me re-think my approach (as their sensitivities could not be classified as any of the traditional eight) and add more categories.
How many senses are there?
The question of how many senses exist has been a topic of discussion for centuries.
Aristotle, a renowned philosopher (384-322 BC), is often credited with being the first to enumerate the senses in his work De Anima.
While it is possible that others may have categorized the senses before him, it is undeniable that the Big Five senses have been recognized for thousands of years. These senses, which are familiar to all of us, are what most people refer to when discussing the concept of sensory perception:
- Sight (vision)
- Hearing (audition)
- Touch (tactility)
- Smell (olfaction)
- Taste (gustation)
Aristotle and his followers believed that our senses serve as a gateway to reality. However, they do not reveal the entirety of reality, though the information they provide is quite substantial. Furthermore, our senses offer a reliable way to perceive reality, particularly at their most basic level.
Advancements in neuroscience have shown that we possess additional senses beyond the traditional five, such as, e.g.:
- proprioception (the body awareness),
- Interoception (perception of the stimuli originating inside the body; perception of the physiological feedback from the body), including:
- thermoception (the sense of heat),
- nociception (the perception of pain)
- equilibrioception (the perception of balance)
Some researchers distinguish even more senses, for instance, Guy Murchie (1978) considered 32 senses, which he divided into five categories:
The radiation senses:
(1) Out of the traditionally identified senses, vision is in this category. However, sight here also includes seeing polarized light and seeing without eyes, such as the heliotropism or sun sense of plants.
(2) The sense of awareness of one’s own visibility or invisibility and the consequent competence to advertise or to camouflage via pigmentation control, luminescence, transparency, screening, behavior, etc.
(3) Sensitivity to radiation, including radio waves, x-rays, gamma rays, etc.
(4) Temperature sense, including ability to insulate, hibernate, estivate, etc. (This sense has its own separate nerve networks).
(5) Electromagnetic sense, including the ability to generate current (as in the electric eel), awareness of magnetic polarity (possessed by many insects) and a general sensitivity to electromagnetic fields.
[Sensitivity to radiation (other than visible light) is the ability to see radiation, for instance, under experimental conditions or during spaceflight it is possible to actually see cosmic rays as points or streaks of light (Gerald 1972). Though most humans are unable to consciously perceive most forms of magnetic radiation because the frequencies are beyond those of visible light, [but it is possible] at least theoretically… to register electromagnetic radiation that lies outside of the normal range” (Jawer 2009).
Sensitivities to magnetism and electricity are well researched in some animals; and there have been reported cases of individuals who can hear radar as buzzes and hisses (Frey & Messenger 1973), someone who receives radio broadcasts through his teeth (Murchie 1978), and it seems that for some autistic individuals this sensitivity can be everyday experience.]
The feeling senses:
(6) Hearing, including sonar and the detection of infra- and ultrasonic frequencies
(7) Awareness of pressure, sense of weight, sense of balance, awareness of one’s proximity to someone or something in their surroundings, and a broad sense of what Murchie calls ‘feel’ – particular touch on the skin, awareness of intra- and intermuscular motion [proprioception], tickling, vibration, cognition of heart beat, blood circulation, breathing, etc.
(8) Feel, particularly touch on the skin and the proprioceptive awareness of intra- and intermuscular motion, tickling, vibration sense, cognition of heartbeat, blood circulation, breathing, etc.
(9) The sense of weight and balance.
(10) Space or proximity sense.
(11) Coriolis sense, or awareness of effects of the rotation of the earth.
The chemical senses:
(12) Smell (with and beyond the nose)
(13) Taste (with and beyond the tongue)
(14) Appetite, hunger and the urge to hunt, kill or otherwise obtain food.
(15) Humidity sense, including thirst, evaporation control and the acumen to find water or evade a flood.
The mental senses:
(16) Pain: external, internal, mental or spiritual distress, or any combination of these, including the impulse and capacity to weep.
(17) The sense of fear, the dread of injury or death, of attack by vicious enemies, of suffocation, falling, bleeding, disease and other dangers.
(18) The procreative urge, which includes sex awareness, courting (perhaps involving love), mating, nesting, brooding, parturition, maternity, paternity and raising the young.
(19) The sense of play, sport, humor, pleasure and laughter.
(20) Time sense and, most specifically, the so-called biological clock.
(21) Navigation sense, including the detailed awareness of land- and seascapes, of the positions of sun, moon and stars, of time, of electromagnetic fields, proximity to objects, probably Coriolis and other sensitivities still undefined.
(22) Domineering and territorial sense, including the capacity to repel, intimidate or exploit other creatures by fighting, predation, parasitism, domestication or slavery.
(23) Colonizing sense, including the receptive awareness of one's fellow creatures, of parasites, slaves, hosts, symbionts and congregating with them, sometimes to the degree of being absorbed into a superorganism.
(24) Horticultural sense and the ability to cultivate crops, as is done by ants who grow fungus, or by fungus that farms algae.
(25) Language and articulation sense, used to express feelings and convey information in every medium from the bees' dance to human literature.
(26) Reasoning, including memory and the capacity for logic and science.
(27) Intuition or subconscious deduction.
(28) Esthetic sense, including creativity and appreciation of music, literature, drama, of graphic and other arts.
(29) Psychic capacity, such as foreknowledge, clairvoyance, clairaudience, psychokinesis, astral projection and possibly certain animal instincts and plant sensitivities.
(30) Hypnotic power: the capacity to hypnotize other creatures.
(31) Relaxation and sleep, including dreaming, meditation, brainwave awareness and other less-than-conscious states of mind like pupation, which involves cocoon building, metamorphoses and, from some viewpoints, dying.
(32) The spiritual senses: include conscience, capacity for sublime love, ecstasy, a sense of sin, profound sorrow, sacrifice and, in rare cases, cosmic consciousness.
Even more senses:
Eco-psychologist Michael J. Cohen has proposed a total of 54 senses, which he has organised into four categories. See the full list here.
Our senses are integral to our perception and interaction with the world. They are vital for our comprehension of the environment and are crucial for our overall well-being. This expanding understanding of our sensory capabilities sheds light on the intricacies of human perception and cognition.
References
Guy Murchie (1978) The Seven Mysteries of Life: An Exploration in Science & Philosophy. Houghton Mifflin Company, Boston. (pp. 178-80).
Michael J. Cohen (2007) Reconnecting With Nature: Finding wellness through restoring your bond with the Earth. 3rd edition, Ecopress.