The way our senses interact with each other means that we actually have many more senses than the 5 proposed by Aristotle.
Stuck in front of screens all day, we often ignore our senses to beyond hearing and vision. And yet, they are always in action. When we are most alert, we feel the rough and smooth surfaces of objects, the stiffness in our shoulders, the softness of bread.
In the morning, we can feel the tingle of toothpaste, hear and feel the water running in the shower, the smell of shampoo and, later, the aroma of fresh coffee.
Aristotle told us that there were five senses. But he also told us that the world was made up of five elements, and we no longer believe that. And modern research shows that we can, in fact, have dozens of senses.
Almost all of our experience is multissensorial. We don’t see, hear, smell and touch in separate parts. They occur simultaneously in a unified experience of the world around us and ourselves.
What we feel affects what we see and what we see affects what we hear. Different scents in shampoo can affect how we perceive hair texture. The scent of roses, for example, makes hair appear silkier.
The flavors in low-fat yogurts can make them richer and thicker in taste without the need to add more emulsifiers. The perception of odors in the mouth, going up to the nasal passages, is modified by the viscosity of the liquids we consume.
There are scientists in the field of neuroscience who believe that there are between 22 and 33 senses.
Among them is the proprioceptionwhich allows us to know where our members are without having to look at them. Our sense of balance depends on the vestibular system of the ear canals, as well as vision and proprioception.
Another example is the interoceptionthrough which we notice changes in our own body, such as a slight increase in heart rate and hunger. We also have a feeling of control when moving our limbs: a feeling that can disappear in stroke patients, who sometimes come to believe that someone else is moving their arm.
There is also the sense of property. Patients who have suffered a stroke sometimes feel, for example, that their arm does not belong to them, even though they still feel sensations in it.
Some of the traditional meanings are combinations of various senses. Touch, for example, involves pain, temperature, itching and tactile sensations. When we taste something, we are actually experiencing a combination of three senses: touch, smell and taste – or gustation – which combine to produce the flavors we perceive in food and drinks.
Taste encompasses the sensations produced by receptors on the tongue that allow us to detect salty, sweet, acid, bitter and umami (tasty). What about mint, mango, melon, strawberry, raspberry?
We do not have raspberry receptors on the tongue, nor is the raspberry flavor a combination of sweet, sour and bitter. There is no palate arithmetic for fruit flavors.
We perceive them through combined functioning of the tongue and nose. It is smell that contributes most of what we call taste.
It’s not about inhaling odors from the environment. Odorous compounds are released when we chew or drink something, traveling from the mouth to the nose through the nasopharynx at the back of the throat.
Touch also plays an important role, connecting flavors and smells and defining our preferences for eggs with soft or firm yolks, and the velvety, luxurious texture of melted chocolate.
Vision is influenced by our vestibular system. When aboard an aircraft on the ground, look into the cabin. Look again when you are climbing.
You will have the impression that the front of the cabin is higher than you, although, optically, everything is in the same relationship as it was on the ground. What you “see” is the combined effect of vision and your ear canals, which tell you that if you are leaning back.
The senses offer a vast field of investigation, and philosophers, neuroscientists and psychologists work together at the Center for the Study of the Senses at the University of London’s School of Advanced Study.
In 2013, the center launched the Rethinking the Senses project, led by my colleague, the late Professor Sir Colin Blakemore. They discovered how modifying the sound of our own footsteps can make the body seem lighter or heavier.
They learned how the audio guides at the Tate Britain art museum, which address the listener as if a portrait sitter were speaking, allow visitors recall more visual details of the painting. They discovered how aircraft noise interferes with our perception of taste and why we should always drink tomato juice on planes.
Although our perception of salty, sweet and sour is reduced in the presence of white noise, umami is not, and tomatoes, and tomato juice, are rich in umami. This means that aircraft noise will enhance the salty flavor.
In a most recent interactive exhibition, Senses Unveiledat Coal Drops Yard in King’s Cross, London, people can discover for themselves how their senses work and why they don’t work the way we think they do.
For example, the illusion of size and weight is illustrated by a set of small, medium, and large curling stones. People can lift each one and decide which one is heaviest. The smallest one seems the heaviest, but people can put them on a scale and find that they all have the same weight.
But there are always many things around you that show how complex your senses are, you just need to stop for a moment to take it all in. So the next time you go for a walk or enjoy a meal, take a moment to appreciate how your senses work together to help you feel all the sensations involved.
