We’ve all been there. You smell a traditional dish and reminds you of your grandma. Or you’re having a nose block and can’t taste anything at all. You disagree with your friend on what the color of the dress is. And you think you saw a familiar face in the way floor tiles. How is it that when you squint, you are sometimes able to see clearly? Why do we do that? What’s happening in our heads? Read further to find out. This is the first part of a three-part series.
Humans are a unique species on this planet. The one aspect that sets us apart from the rest of the animal kingdom is this mental capacity to introspect, to ‘look inwards’ (Sapiens, as in Homo Sapiens means ‘wise man’ in Latin). This in no way means that this ability and the related need is perfect. Take, for instance, the simple act of observing an object. How does the brain help us perceive the world around us?
We may consider the perception of the world around us is a straight shot of what the eyes and ears offer. Right? Well, there’s a lot more that happens and is interesting to learn that what our eyes, for example, sees is very different from the final image we get to experience. The brain handles a lot of raw data that isn’t ordered or coherent to start with. But the creative genius that it is, the brain then goes on to fine-tune and provide an output that is a precise illustration of an image or a sound or even taste. This very same awe-inspiring ability of the brain though has its share of misfires.
Back in school, I learned that there are five senses (vision, hearing, taste, smell, and touch). Seems there are more senses like proprioception, balance, and appetite. But the latter are internal features that help us understand the state of our bodies. The main five senses help us in understanding our surroundings.
The sense organs themselves are very functional in nature. They pass on a ton of information through an intricate neurological network to the brain, which then adds more clarity to help us interact with the world. Let’s look at how each of these senses is weird, inter-connected and trick us every day.
Smell (Olfacoception)
Did you know that one study discovered humans can smell around 1 trillion odors? Not only that, the perception of smell is the first sense to have evolved and is the first sense that the fetus develops in the womb (the developing baby smells what the mother is smelling). There’s one more special aspect of this sense. The olfactory neurons are one of the very few types that regenerate. Scientists are working towards using this and rebuilding damaged neurons (those in the spine, for example).
This ‘Wolverine factor’ might be necessary, since these neurons interact directly with the outside world. So, this is what happens when you ‘smell’ something. Any substance can trigger the olfactory neurons through chemicals (that add an odor). They send electrical signals to the olfactory bulb (a library of odors) which forwards it then to the olfactory nucleus and the piriform cortex. Once the brain has an understanding of this, you ‘smell’.
The olfactory bulb not only maintains a repository of odors but is situated right alongside amygdala and hippocampus, being a part of the limbic system itself. This explains why certain smells trigger memories in us. Companies, eateries and even stores try to exploit this smell-memory partnership, but with limited success. But there is another way to trick people into provoking emotions. Just give the right name for it.
Let’s not get too hyped up about our ability to smell though, since odors can not only fool your nose, the brain itself gets very limited information from the olfactory neurons. We also aren’t good at judging based on smell (and without visual cues). Now, illusions are harmless as they are a result of ‘misreading’ the information. Hallucinations are a serious matter, the result of the malfunctioning of the system, resulting in people often smelling a ‘burnt odor’ and requires immediate medical help.
Taste (Gustoception)
The next sensory system that is set-off by chemicals is taste. Smell and taste work in tandem with the former having a significant effect. Although conventionally taste is divided into five categories (salt, sweet, bitter, sour and umami), there are others as well (astringency, pungency, metallic etc.). Many believe that taste receives far more attention than it deserves as it is the weakest sense.
Taste is so unreliable at times that many of the experts who seem to have a good understanding of the various types of a particular food product (wine, cheese etc.), may be able to do so thanks to their brain and not their tongue. A little bit of creativity does help at times.
Remember how we fail to taste when a cold hits us or the nose gets clogged? This shows how taste, being a weak sense has to depend on other senses, especially smell. Robert. M. Weiler showed in a 1999 study that when blindfolded and noses plugged, people couldn’t discern if what they tasted was an apple, potato or onion (when they had to taste only one). In a normal scenario, when we ‘taste’, it’s to do with the odor the food carries in most cases. But the brain interprets it as a taste since a large portion of the sensation arises from the mouth. The next time you think a food tastes very good or otherwise, you should consider this point. It may be much to do with the smell.
Notes
Burnett, D. (2016).The Idiot Brain. 1st ed. London: Guardian Faber Publishing.
A 2014 study conducted by Caroline Bushdid and her team investigated the previous existing claim that humans can smell up to 10,000 odors. The study helped discover that the range is a lot more than that.
A 2001 experiment conducted by researchers Herz and von Clef showed that people reacted differently to the same smell when the associated product was named differently.
Proprioception is the sub-conscious knowledge of the spatial presence of our limbs. Balance is the act of maintaining an upright posture in standing or locomotion, regulated by the inner-ear. Appetite refers to the natural instinctive desire for food. It should be distinguished from hunger, which is the body’s craving or need for food. [Source: The free medical dictionary]
Astringency is a tactile taste felt as a dry, rough feeling in the mouth and contraction of the tongue tissue. [Source: Science Direct]