According to Barry Smith from the University of London, human perception is a complex multisensory process. It is shaped by the interaction of numerous sensory organs that together create our understanding of taste, movement, balance, and the surrounding world.
Neurobiologists are now focusing on perception as a distributed system where sensory channels interact with each other, forming a holistic perception of reality. A change in one of these channels, whether it be sound, aroma, or movement, can subtly influence how we perceive various aspects of the world around us.
Modern technology and hours spent in front of screens can make us forget about the multitude of sensations that go beyond sight and hearing, even though they are always active. With attention, we can notice details, such as the contrast between smooth and rough surfaces, tension in our shoulders, or the softness of bread in our hands.
Every day we encounter such subtle signals: the morning tingling from toothpaste, the sound of water in the shower, the aroma of shampoo, and later, the smell of freshly brewed coffee.
Although Aristotle identified five senses, he also claimed that the world consists of five elements — an idea that we now know to be outdated. Modern research shows that our perception is much more multifaceted than just five senses.
The diversity of our experience depends on the functioning of various sensory organs.
Most of our perception is multisensory. Vision, hearing, smell, and touch do not function in isolation; they work together to create a continuous perception of both our body and the surrounding world.
What we feel influences our vision, and what we see influences our perception of sounds. For example, different scents of shampoo can alter the perception of hair texture: the smell of rose can make hair feel silkier.
Taste, such as that of low-fat yogurt, can be perceived as richer without adding extra ingredients due to aromas. The perception of flavors in the mouth changes depending on the viscosity of the liquids consumed.
Humans have more sensory organs than commonly believed.
My colleague, Professor Charles Spence from the Crossmodal Laboratory at Oxford, claims that according to neurobiologists, humans have between 22 to 33 sensory organs.
Proprioception allows us to be aware of the position of our limbs without needing to look at them. We also sense balance thanks to the vestibular system, vision, and proprioception.
Interoception is another important aspect that helps us feel changes in our body, such as an increased heart rate or hunger. This sense also allows us to be aware of limb movement. Patients who have suffered a stroke may lack this sensation and may even think that someone else is moving their hand.
This leads to a sense of ownership: patients may feel that their hand does not belong to them, despite having sensations in it.
The intertwining of taste, smell, touch, and balance.
Some traditional sensory organs represent mixtures of several sensations. For example, touch includes the perception of pain, temperature, itch, and tactile sensations. When tasting food, we actually use a combination of touch, smell, and taste, which ultimately shapes our impression of food and drinks.
Taste sensations depend on receptors on the tongue that allow us to distinguish sweetness, saltiness, sourness, and bitterness, as well as umami. But what about fruits like raspberries, mangoes, or melons?
There are no receptors on the tongue for perceiving the taste of raspberries, and it is not a simple combination of sweet, sour, and bitter. There is no arithmetic system for fruity flavors.
We perceive them through the synergy of the tongue and nose. Smell plays a key role in what we call taste, as aromatic compounds are released during chewing or drinking and travel from the mouth to the nose through the pharynx.
Touch also influences the perception of taste and smells, determining our preferences, for example, between liquid and solid eggs or the texture of chocolate.
Visual perception can change depending on the functioning of the vestibular system. For example, when you are on a plane looking down the aisle, and then as the plane ascends, it may seem that the front of the cabin is higher, even though everything is actually on the same level.
Research shows how sensory organs shape behavior.
Research on sensory organs is a vast field, and philosophers, neurobiologists, and psychologists work together at the Center for the Study of Sensory Organs at the University of London.
In 2013, the "Rethinking the Senses" project was launched here, led by my late colleague, Professor Sir Colin Blakemore. We found that changing the sound of one's footsteps can influence the sensation of lightness or heaviness of the body.
We also learned that audio guides at Tate Britain, which address listeners as if speaking to a model in a portrait, help better remember visual details of paintings. We discovered how airplane noise affects taste perception and why it is always worth drinking tomato juice on a plane.
Interestingly, the perception of sweetness, saltiness, and acidity decreases in white noise conditions, while the umami taste remains unchanged, making tomato juice particularly appealing on board.
Everyday illusions demonstrate the complexity of our sensory perception. At our interactive exhibition "Senses Unwrapped" in the King's Cross area of London, visitors can learn about the functioning of their sensory organs and understand why they do not function as we might think.
For example, the illusion of size and weight is demonstrated using a set of curling stones of different sizes. People can lift them and determine which one is the heaviest, but on the scales, they will turn out to be the same.
There are many examples around us that show how complex our sensory system can be if we take the time to evaluate perception. So next time you are walking outside or enjoying a meal, try to pay attention to the interaction of your senses and how they enrich your experience.
Adapted from an article originally published in The Conversation
Note: Barry Smith's research on multisensory experience was supported by the Arts and Humanities Research Council, which laid the foundation for this exhibition dedicated to the senses.
