Your brain, your senses and the illusions in between
What is this trickery?
I noticed this post popping up on social media again recently and it got me thinking about perception…again.
If you haven’t seen it before, notice the red can. Zoom in a little and you’ll see the entire picture is in fact printed in black, white and teal only.
There’s a famous saying that says “seeing is believing” but that’s not always the case.
Most all sensory information is processed by the brain automatically, without conscious awareness. This helps us to interpret things quickly and efficiently.
When we see something, our brain quickly analyses patterns, shapes, colours, and other visual cues, relying on past experiences and built-in shortcuts to make sense of what we're seeing.
For example, certain illusions might use patterns that make our brain think something is moving when it's not, or they might use colours and shading to make us see depth or shapes that aren't really there. Ergo, the infamous red (not red) Coca-Cola can.
Since these processes happen subconsciously, we're not aware that our brain is being tricked. We just see the illusion and perceive it as reality, even after we logically know it's not true.
But it’s not just what we see that can give us false information. All of our senses can be tricked.
1. Auditory Illusion:
You may have come across the “green needle / brainstorm” auditory illusion. https://www.youtube.com/watch?v=qXxV2C1ri2k
2. Tactile Illusion:
The Rubber Hand Illusion tricks your brain into believing a fake hand is part of your own body. When the rubber hand is stroked you will feel it as if it’s your own hand. If you wear a hat for a long time and then take it off, it can still be felt. Try twisting your tongue upside down, and run your finger along the front, it will feel like the finger is moving in the opposite direction. Weird right?
3. Taste Illusion:
Expectation based on colour. Our brain associates certain colours with specific flavours due to past experiences. For example, you might expect a red drink to taste like cherry or strawberry, a yellow drink to taste like lemon, and a green drink to taste like lime or apple.
Here’s a fun little experiment by Doctors Xand and Chris Van Tulleken:
In hypnosis, there is a suggestibility test known as “The Lemon Test”. Here’s an incredibly simplified version you can do right now:
Close your eyes and visualise, in as much detail as you like, taking a cold ripe lemon out of the fridge, imagine holding it in your hands, put it down and cut it into quarters, pop one of the juicy quarters into your mouth and bite down. Unless you’re trying pretty hard to resist, you will have noticed you have more saliva in your mouth then you did a moment ago. Your brain has produced the saliva as if you were actually eating the lemon.
4. Olfactory Illusion:
A few years ago, there was a study that resulted in some very red faces in the wine tasting / wine snobbery (I admit to being one) world. A researcher dyed a white wine red and gave it to 54 wine science students. The budding experts overwhelmingly described the wine as they would a full-bodied red. It was not only the wine that was red, their faces must have been a picture.
Even when you know how or why you’re seeing or experiencing an illusion, it’s not easy or in some cases not even possible, to make a conscious choice to override them.
Is an illusion the same as a hallucination?
No.
As with illusions, hallucinations can occur in any of the five senses. The difference however, is that hallucinations are unique to the individual experiencing them and are not shared.
A hallucination is a perception in the absence of any external stimulus. In other words, it’s a sensory experience that occurs without any input from the external environment.
More often, hallucinations will occur as a result of mental health conditions (such as schizophrenia or bipolar disorder) substance use, neurological disorders, sleep deprivation, or extreme stress.
In general, sensory illusions are not harmful and are a natural part of how our brains process sensory information. They can actually be quite fascinating and provide insights into how your marvellous mind works.