It all depends on how you define things. The idea of five classical senses dates back at least to Aristotle, himself a rather classy guy. In De Anima Of the Soul he argues that, for every sense, there is a sense organ. Because when you start counting sense organs, you get to six right away: the eyes, ears, nose, tongue, skin, and the vestibular system. We now know that the vestibular system, located in the inner ear, is an integral part of how we balance ourselves, but it also plays a critical role in vision, allowing us to keep our two eyes focused on things even while our heads are moving about.
Instead of a sense organ, each separate sense really only requires a different kind of sensory receptor. In the skin alone, there are at least four different kinds of sensory receptors: those for touch, temperature, pain, and proprioception or body awareness. A sensory receptor is a specialized cell that sends electrical signals to the brain in response to the type of stimuli the cell is optimized for. Even senses that seem fundamental, such as vision, are intimately entwined with other senses that seem separate.
In the moments when your heart contracts and pushes blood out to your arteries, your brain takes in less visual information from the world. Examples are flavour, which the brain constructs from gustatory taste and olfactory smell data, and wetness, which is created from touch and temperature. As you can see, there is no single, logical way to define the senses. In some ways, it might make little sense to draw divisions between them at all — considering that they often seem to blend together; the colour of food — and even the sounds of a restaurant — can influence taste, for instance.
Understanding these relationships is important when studying conditions like synaesthesia and could even shed light on consciousness itself. Indeed, once you start thinking about all the different kinds of information reaching the human brain, you might even find that you develop a brand new sense — a radar-like sensitivity to some of the other misconceptions regarding the way the brain experiences the world.
In Depth Brain. Psychology: How many senses do we have? Share using Email. By Christian Jarrett 19th November We often talk of having five senses as a universal truth.
In reality, there may be more — or fewer — depending on the way you look at the question. Christian Jarrett explains the controversy.
First, light reflects off an object to the eye. The transparent outer layer of the eye called the cornea bends the light that passes through the hole of the pupil.
The iris which is the colored part of the eye works like the shutter of a camera, retracting to shut out light or opening wider to let in more light. Then, it [the light] passes through the lens, which continues to focus the light," explained Dr. The lens of the eye then bends the light and focuses it on the retina, which is full of nerve cells. These cells are shaped like rods and cones and are named for their shapes, according to the American Optometric Association.
Cones translate light into colors, central vision and details. The rods translate light into peripheral vision and motion. Rods also give humans vision when there is limited light available, like at night.
The information translated from the light is sent as electrical impulses to the brain through the optic nerve. People without sight may compensate with enhanced hearing, taste, touch and smell , according to a March study published in the journal PLOS One. Their memory and language skills may be better than those born with sight, as well.
This sense works via the complex labyrinth that is the human ear. Sound is funneled through the external ear and piped into the external auditory canal. Then, sound waves reach the tympanic membrane, or eardrum. This is a thin sheet of connective tissue that vibrates when sound waves strike it. The vibrations travel to the middle ear. There, the auditory ossicles — three tiny bones called the malleus hammer , incus anvil and stapes stirrup — vibrate.
The stapes bone, in turn, pushes a structure called the oval window in and out, sending vibrations to the organ of Corti, according to the National Library of Medicine NLM. This spiral organ is the receptor organ for hearing.
Tiny hair cells in the organ of Corti translate the vibrations into electrical impulses. The impulses then travel to the brain via sensory nerves.
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