Everyone learns about taste, touch, smell, sight, and sound when they’re growing up, but could a mere five senses really encapsulate the whole of human experience? Believe it or not, there are a number of senses either simplified for primary school or that you may never have even noticed you have.
In total, modern scientists understand the average human to have up to ten senses, with over 22 sensory organ systems in total.
How do you know which direction is down? Why is a rollercoaster exciting? Our sense of balance relies on sensory organs known as vestibules. Located in the inner ear, three canals monitor movement via small sensory hairs. As these hairs are stimulated, they send messages to the brain conveying the direction of movement.
Our sense of gravity comes from the movement of sacs next to the cochlea. These sacs contain millions of tiny crystals which stimulate small hairs signaling position.
Damage or overstimulation of the vestibular system is what causes vertigo and car-sickness.
Close your eyes and touch your finger to your nose. You just used your kinesthetic sense. Kinesthesis or proprioception is your ability to sense your body parts in relation to each other. It’s a sense controlled by the parietal cortex—the portion of the brain responsible for movement and touch—that combines with our sense of touch an balance to allow us to move with precise coordination.
Damage to this sense can hinder bodily movement and even cause people to lose the ability to sense 3-D objects via touch. This sense is easily impaired by alcohol and is famously tested by law enforcement officers as part of sobriety tests.
Feelings of heat have nothing to do with touch. You may be able to feel a warm mug of coffee while touching it, but you can also sense radiant heat. These signals are captured by heat receptors in your skin and passed on to the brain. These receptors sense changes in temperatures. Accustomed to your body temperature, when they sense a decrease in temperature, that’s cold, and an increase is warm. Many chemcials— like alcohol —can affect or even trick this sense, making ice or liquor burn.
This sense combines with touch for us to sense something as wet. The soft feeling of a liquid paired with a cooling in temperatures is added up in our brain to mean moisture or water.
Though pain and damage can be perceived by our senses of touch and kinesthesis, we also have specific receptors dedicated to sending pain responses to the brain. Important for self-preservation, this sense covers our skin along with much of our internal organs. This sense fires whether activated by physical, thermal, or chemical pain.
Many things can be used to manipulate this sense, and it is often intentionally disabled by physicians. The most direct way to disable this sense is to cut off its pathway to the spinal cord and brain, which is what anesthesia does.
What makes you hungry or have to pee? Interoception is any sense felt by special receptors inside your body. Scientists still aren’t sure how every aspect works, but scores of stretch-sensing and chemoreceptors signal all sorts of bodily conditions to the brain.
First observed by 19th-century naturalist Charles Darwin as the sensation of “viscera,” our internal sensations have even been linked to how we feel emotions—lumps in our throats, butterflies in our stomachs. Beyond those, our brain makes thousands of sub-conscious adjustments based on feedback from our internal organs.
Beyond the dedicated sensory systems we have, our brain combines them in ways that allow us to perceive all manner of other virtual stimuli, including the passage of time, fear, and all manner of decision-based chemical reactions in the brain. As scientific research continues, our list of senses—or even our understanding of what senses are—grows as well.
