As you read this, you’re almost certainly using your sense of touch. You might be scrolling through this article on your phone, or using the scroll function on your laptop instead. Either way, touch is involved.
Although we use it often, our sense of touch doesn’t always feel as compelling as our other senses. When recalling a memory, we tend to latch on to what we saw, heard, and maybe smelled, not what we physically felt. However, touch is one of the most important senses for helping us navigate the world, as anyone who’s ever accidentally touched a hot stove will know.
How does our sense of touch work? Where does pain factor in? And, why doesn’t touch feel as visceral as our other senses do? Let’s delve in and answer all of these “touchy” questions.
First, Your Skin Encounters an Object
We all know what it means to touch something—to come into physical contact with an object. Even if a layer of clothing or another barrier is in the way, our skin is still able to register that we’re touching something.
That’s because your skin contains sensitive receptors poised to take in information about the world around them. Even if you don’t touch an object, your sense of touch can still be engaged–you can feel the temperature of a room, for example, or a breeze hitting your skin.
When compared with the other senses, touch often seems deceptively simple. While our eyes, ears, noses, and tongues are delicate and complex organs, the skin doesn’t seem quite so interesting. In the past, even neuroscientists haven’t studied how touch affects the brain as much as how the other senses do.
However, touch does a lot more than it seems to at first glance. For example, we can feel different types of touch, such as vibration, pain, and texture. Our sense of touch also helps us understand where we are in relation to a room or other people in it.
Different kinds of sensory nerve receptors in your skin enable you to experience the world through touch. Your body actually has three different types of touch receptors to make sense of what you come into contact with:
- Nociceptors: These receptors sense pain in the simplest form—they can tell when skin cells get damaged. However, they can’t distinguish between different types of pain.
- Thermoreceptors: These receptors are responsible for detecting temperature. Some of your thermoreceptors detect heat, while others detect cold.
- Mechanoreceptors: These simply report any contact with the skin, whether it’s a light gust of air or the firm grip of a handshake.
Some parts of the body are even better at sensing touch than others. For example, your soles, palms, lips, and genitals all contain Merkel cells, which make these areas far more sensitive to touch than your other body parts.
Next, Your Nervous System Signals Your Brain and Body
From these receptors, signals get passed through your neurons and the nervous system to your brain.
Depending on the type of touch involved, the neurons can take a different pathway to reach your brain. Each type of receptor sends its signal along a unique path. However, these touch messages are all destined for the same part of your brain: the sensory cortex.
Sometimes, you react to touch before the signal reaches your brain. For example, when you touch something dangerously hot or painful, you’ll quickly move to protect yourself. That’s because the signal went straight to your spinal cord and was processed there, triggering a reflex before you had time to think about it.
Of course, the information processed by your spinal cord does eventually make its way to your brain. However, it will land there after you’ve already reacted to the situation.
Finally, Your Brain Figures Out What to Do
At the sensory cortex, your brain unpacks the touch signals that it’s received and makes sense of them. The sensory cortex contains a “map” of your nervous system, so you can quickly and easily figure out from where on your body the sensation of touch came.
And, while touch may seem to be the sense that’s least likely to stick in our minds, research suggests something surprising: hearing is the sense that’s worst for memory. We can remember touch about as well as we can remember sight, even though sight often feels easier to remember.
Touch actually leaves a powerful impression on our memories. For example, one study found that blindfolded research participants who touched an object were later able to easily point out what they had touched just by looking at it, even though they’d never seen that object before.
However, when touch-related information is stored in our memories, we rarely seem to be consciously aware of it. This could be why touch doesn’t seem to be a compelling sense in terms of memory, even though it’s among the senses that we recall the best.
Touch might be the sense that we most often take for granted. Perhaps because it was one of the first senses that we evolved, it’s so primal as to seem commonplace and dull. But touch plays a critical role not just in how we interact with the world, but in how we remember it later. You might still be scrolling through this article on your phone, but that scrolling process feels a little more interesting now, doesn’t it?