Do You See What I See?

By Jeremy Ireland on February 9, 2021 in Other

Flip her over. Photo: Dennis Thatcher

Do you remember those three-dimensional optical illusions you’d see in the puzzles section of the Sunday paper? At first glance they’d just look like an odd psychadelic pattern that kind of made your eyes hurt, but after a while a three-dimensional image would take form. These images, known as stereograms, enable a two-dimensional image to be interpreted by the brain as a three-dimensional one.
If you could never see the three-dimensional image, don’t fret. Just like hating coriander or not being able to smell asparagus in your pee, there is a minor genetic component to it, all three of which I am privy to. That said, it’s fair to say that the majority of any illusion comes in the form of a ‘cognitive illusion’, in other words the brain is processing what it sees and trying to translate it into something tangible. In the case of our stereogram, the brain is processing the difference between what our left eye sees and what our right eye sees, allowing the mysterious three-dimensional shape to appear.
With a 3D movie, the film actually contains two slightly offset images, but unlike a stereogram we use special glasses with a green lens and a red one in order to view it. It’s worth noting here that it’s not the glasses achieving the illusion; the three-dimensional effect is actually achieved in the film production process. From 3D films we go to ‘virtual reality’, a totally simulated experience. Here, by putting on a VR headset, and possibly some hand controllers, the user can immerse themselves in a completely new world, such as a video game or military training.
The main point is that all of what we see, hear, smell, taste and touch are messages that get translated into an electrochemical language that is then delivered deep within the brain. It basically boils down to sensation and perception, a process that we often take for granted.
Let’s put it to the test with my all time favourite, the Margaret Thatcher illusion. To start, we need an upside down picture of Ms Thatcher (see above), then flip the picture horizontally so it’s the right way up. What do you see? Suddenly she turns into the Iron Lady. In the inverted state the face looks almost normal, but the right way up it becomes grotesquely hideous. Margaret might be pleased to know that it’s not just her that gives this effect, but it does demonstrate the relationship between sensation and perception.
There are many other classic illusions used in psychology texts to help teach the idea of sensation and perception. The Neckler cube changes direction the more you stare at it. There’s also the Penrose triangle and the Rubin vase, just to name a few. Despite these illusions being quite obvious within the visual domain, the important thing to realise is that there is more than one interpretation of the physical image. For example, with the Rubin vase some people will see two faces facing each other and some will just see a vase.
What’s the take home message here? What you see is not necessarily a true reflection of what the world presents, a concept we can use across many platforms. What we really see is an interpretation or perception by our brain of a message delivered by the physical world. What is the relationship between physical reality and psychological reality? Well, like many other things that rely on our brain, our sensory systems and perceptual process reflect the combination of nature and nurture. On that note, I’m determined to bust that stereogram.