Do you have a sixth sense? How about a ninth sense?
If you’re human you have at least twenty-one senses according to recent studies and writers can use every single one of them to bring our characters to life.
For years everyone has been taught, from kindergarten through high school biology, that we have five senses–seeing, hearing, smelling, tasting, and touching, and maybe possibly a sixth sense for those into the paranormal. But this is old news. Really old news. The idea of five senses dates back to Aristotle and science has progressed a great deal since his time.
So, if you ask researchers today how many senses humans have, you’ll receive a variety of responses. For years, scientists have been arguing about the actual number. Recently, the most common answer is around twenty-one.
Some researchers believe that our basic five senses can be split into sensory subgroups. Sight, for instance, can be further divided into the senses or perceptions of brightness, color, and depth.
Other scientists argue that senses are unique entities, not subgroups. In this theory, each sense consists of cell types that respond to a distinct phenomenon and then sends a signal to a specific region of the brain. With that definition, we have more than five senses.
The increased number of senses surprises most people, until they become aware that they are using most of them every day just to survive. Writers can utilize these senses to enliven and enhance their writing.
In addition to those already mentioned, here are the remaining senses:
Equilibrioception. This is balance, that sense that keeps us standing upright, coordinated by the vestibular region of inner ear with a little help from our eyes. You can use this sense in describing fast-moving sports, fights, or states of drunkenness.
Interoception. These are multiple sensory receptors found on internal organs. They each have a different function depending on location:
The feeling of being full or satiety is controlled by stretch receptors in the stomach after one eats. We’ll take notice of this sense on Thanksgiving. And likely ignore it.
Then, there are chemoreceptors in our blood vessels monitoring oxygen and carbon dioxide levels, which will quickly inform us that we can’t get enough air or that we are suffocating. That’s where the panicked feeling that you can’t breathe comes from.
There are stretch receptors in our lung tissues that sense how full our lungs are.
Your breathing rate is controlled by the combination of how full your lungs feel and how much oxygen you are receiving. Some people also believe yawning could be a response to these sensory inputs.
Then there are those pesky chemoreceptors out of our control which tell the brain you need to vomit. Now!
Itch. Another annoying but necessary sensory perception is itching, which can occur with or without touching anything. It tells your brain something is irritating your skin, which could be anything from bugs or poison ivy to dry skin. Sometimes just thinking about it makes our skin itch and we want to scratch. This sense draws our attention to a specific location on our skin.
Magnetoreception. Some people have a natural sense of direction and/or navigation and always seem to know which way is north or how to get home. They, like homing pigeons, are employing a sense of magnetoreception. They’re ‘feeling’ the surrounding magnetic fields.
Nociception. This is the sense of pain. In the past, pain was considered a response to touch, but it’s really a specific experience in its own part of the brain. Current researchers suggest that pain is actually three different senses, each relating to different kinds of pain occurring in different locations: pain in our skin (like a sunburn or a splinter) is different from pain in our bones (broken bones), and different from pain felt in an internal organ (for example, angina is heart pain, while gas and bloating are intestinal pains). All pains have a similar function, however, which is to tell your brain you are in trouble.
Proprioception. This is body awareness. If you close your eyes or go blind, you still have an idea where your hand is or if your legs are crossed.
Try going downstairs in the dark or with your eyes shut. You have a sense of where your hand is as you reach for the banister. You know where your foot is and you know when you expect it to touch the next step. (What if that step wasn’t there?)
Without this ‘sense of yourself’ you’d have to watch your hands every second to see if they are going in the correct direction and grabbing the right thing. Or you’d need to stare at your feet to see when your shoe is nearing the floor. Without this sense we couldn’t walk or even pick up a fork without problems.
Body awareness is affected by one’s alcohol consumption and by some illnesses. Police are checking proprioception in some of the field sobriety tests.
Thermoception. This is the sense of temperature, of feeling warm or cold. It comes from temperature sensors in our skin and travels to the brain via our spinal column. It helps tell your brain to do something quick so you don’t freeze in the snow, walk into a fire, or dehydrate in the desert heat.
Temporal perception or Chronoception. This is the basic sense of time passing, the sense that controls our circadian or daily rhythm.
Time passing may seem different depending on what we do (we tend to think time passes fast if we’re having fun) or at different stages of life (younger people are more accurate in guessing the passage of time, while older people feel time passes faster and faster every year), but we all have a sense of time passing.
Finally, some people believe in ESP, the extrasensory perception, which could now be relegated to being the twenty-second sense instead of the sixth. More studies, of course, are needed to see if this is a true sense. Anyone with ESP care to make a prediction?
In the natural world we notice that many of the animal senses are more powerful than the human versions. In addition, there are a vast range of senses that humans do not have, often quite strange and unbelievable. (A debate exists whether perhaps some unknown senses are hidden in human DNA and we just haven’t developed them, or maybe we aren’t aware of them. Not yet, anyway.) But we can still write about them.
So, if you write about animals or superheroes or alien forces, you should investigate some of these:
We know dogs have a limited sense of color vision, but they have an extraordinarily keen sense of smell, millions of times more sensitive than humans. Much scarier, bears have an even greater sense of smell than dogs, picking up scents miles and miles away. Some animals can also smell across time (wow!), knowing which scent came before another, like they’re stacked in layers.
Cats can see at night, their large eyes requiring a small fraction of the light required by people. Eagles and some other birds have spectacular distance and night vision.
Bats and snakes can see infrared light, which is beyond red on the electromagnetic spectrum. Infrared is invisible to humans. The main source of infrared is thermal radiation, which allows warm objects to be seen at night by those creatures with infrared vision. Snakes use their tongues to sense heat signatures of prey and can follow its movements.
The Electromagnetic Spectrum
Bees and dragonflies and jumping spiders see ultraviolet (UV) light. Seeing ultraviolet light means you can see beyond violet, the shortest wavelength on the visible spectrum. So these creatures see patterns and markings that the human eye cannot see. UV light is used by art historians and curators to see the layers of pigment in paintings and to discover what might be in deeper layers.
Certain kinds of shrimp can see ‘all the above’ plus they can also see polarized light and, to boot, they can move their eyes different directions and see all 360 degrees around them. Next time you eat shrimp, think about that.
Birds, bees and cows can navigate by using their sense of the magnetic fields. Monarch butterflies can navigate across generations, hatching somewhere in the USA and later migrating to trees in Mexico where their ancestors once lived. Imagine taking off and going to the exact ancestral home of a long dead ancester in another country or on another continent without having an address nor a living relative to guide you. That is one unbelievable sense.
Sharks and the platypus sense electric field changes in the waters around them. Most naturalists feel that alligators have the most acute sense of touch of all creatures, feeling the faintest of faint vibrations with sensors on their skin.
Cephalopods, like the octopus, have chemoreceptors in their skin to sense their surroundings, so they can change their own skin color, texture, and patterning to camouflage themselves. Some beetles (that need to lay their eggs in dead trees) can sense a fire many miles away.
Elephants hear low frequency sounds that are infrasonic, which lie far below our hearing range. They can also sense seismic vibrations in the earth with the pads of their feet.
Dogs and mice hear higher frequencies than we do, hence dog whistles and plug-in pest repellents.
Some birds and other animals can sense what nutrient is missing in their diet (without a blood test or a dietician) and then seek out the necessary food. Don’t you wish you could do that?
Amazing stuff! And scientists aren’t done researching our sensory worlds. They’re likely to discover many more extraordinary abilities in nature and then utilize that information to invent things to enhance human existence.
Sensory details add depth to any description, so feel free to explore more than just the original five senses in your characters’ experiences.
Do you have a favorite sense to write about? Can you imagine a sense you wish you had?
Kathryn Sant is a retired obstetrician who has witnessed the births of thousands of future readers. She has published a middle-grade novel, Desert Chase (Scholastic), and under the pseudonym BBH McChiller she is a co-author of the fun, spooky Monster Moon mystery series. Curse at Zala Manor is Book 1, Secret of Haunted Bog is Book 2, and Legend of Monster Island is Book 3. She is currently working on two middle-grade boys’ adventure novels and the next Monster Moon book.
Her interest in adventure, research, and genealogy has led to a love of world travel, exotic adventures, and museums of all kinds. But she also enjoys quiet evenings reading with her dogs at her side.
(Clock photo by dreamtime. Other photos by Kathryn Sant.)