Seeing is believing – or is it?

We all perceive things that others don’t, simply because much of what we perceive of the worlds is within our minds, not in the world itself. It matters not what we each perceive, but how what we perceive forms our assumptions about the world, which inform our actions. Consider that 3 in 100 people regularly perceive hearing voices and seeing being that 97 in 100 people do not regularly see. 1 in 3 of these people are not at all bothered by the additional perception, 1 in 3spend a lot of time in and out of health institutions and the other 1 in three suffers in silence. The point here is that 2 in 3 people who hear voices and see beings do not use the health services to continue living their lives. If seeing and hearing these beings was the problem, then 3 out of 3 would be using health services. It is those who have not found ways of working their perceptions for their own gain that have the troubles.


Many of our reactions to the world are based on how we perceive the world. Perception is the interpretation of the sensory information that we are given to create a landscape of what the world around us is. Part of that perception is pattern recognition which helps us to predict what is coming next. We have many senses, the most common of these is sight, hearing, touch, taste, and smell (there are more, such as motion, temperature and so on – about 15 all up).


Despite your expectations, perceiving the world accurately, on average, is not vital to your survival. You are making many assumptions all of the time about what you think is there and these assumptions are often wrong. 


I will focus mainly on sight for this article, since it is commonly regarded that sight is the dominant sensory input and the most immutable. Sure we see the world for what it is? Consider the phrase “seeing is believing”, which is made up of the idea that to see something is to know it is real.


Take a gander at the video clip here.



In this video, you see what looks like an ordinary room. The girls are the same height, but when one goes to the right she seems to grow and as she goes left she shrinks. I appreciate that this room is artificially created to fool you, however it illustrates a point, which is that what you perceive is not necessarily what you perceive. After all, the girl does not actually change size at all, the room shrinks. Your memory of how rooms work tells you that rooms are square, thus objects in what looks like a square room must be the same size, therefore the girl must be growing and shrinking. In essence your expectations have fooled your mind.

In this perceptual illusion the dancer seems to be spinning. When you watch it, you will see that the dancer appears to spin in a particular direction. If you watch carefully, you can change the direction that the dancer spins. This is done via changing your expectations (I found staring at the shadow the dancer casts as a good way to switch directions). You haven’t changed the video image, but you have changed your interpretation of the images.

Of course vision is not the only perceptual sense that can be fooled. listen to this video clip. Play it twice to hear what I refer to. It is the same video the second time around, but you will perceive it to be a higher pitch rather than starting from where you first thought it should start. All the senses can be fooled by stimuli, or rather our perception of all of our senses can be fooled. Try sitting in the bus and sitting behind the driver. Look at the road passing in the reflection of the glass blocking you from the driver (if your bus is designed that way). After a while you will probably begin to perceive motion in reverse.

Moving back to sight, consider colour. Most of us have colour vision, yet half of the human species is partially colour blind. I can’t currently find a reference for this (sigh), but it is mostly manifest in the differentiation of blue and green. When does a colour stop being blue and start being green? Well, ask a sampling of men and women whether this colour is blue or green:


Yes, you have to pick one. Most women will call this colour green, while most men will call this blue (computer screens may cast this colour improperly and muck up this experiment, but drag someone to the fabric or paint store and see where they have a range of colour and argue about the different representations of teal and aqua). Part of this is a cultural definition but most of it is genetic. The part of the genes that corrects for colour blindness is on the second x chromosome that men don’t have. While this can influence fashion sense, it generally does not significantly affect survival. The point of this bit of the article is to point out that what you are expecting to see i the world is not actually what you probably are seeing in the world, but id isn’t harming you.



Much of what we perceive of the world is not really the world at all, it is merely expectations, what we expect to see, and thus our mind fills in the blanks. Consider the most efficient use of brain space – interpreting masses of information given to our brain from our eyes, or to assume much of the information from our memories of what is probably there. Try this exercise – pick an object and stare at it. Try really hard not to move your eyes or blink. Now notice that your peripheral vision shrinks, except for any moving object – don’t look away! If you manage to stay still enough, you may notice that your eyes are wiggling… see if you can still this too. If you succeed, and few do, you will notice that your vision fades. This is because we only see the bits that change. To see stationary objects, our eyes wiggle back and forth, helping as define different objects. Yet if we fix our attention on one thing much of the rest of our visual perception becomes simplified with only gross changes being picked up as relevant.


Hopefully we have established that much of what you perceive is not actually what you sense, it is informed by what you sense, but filled in with memory and expectation. Here is a good trick to do with babies. Put a ball on the table, place a cup on the ball. Lift the cup and the child sees the ball again. Now put the cup on the ball, move it to the side of the table and let the ball drop into your hand without shifting the height of the cup. Now lift the cup and see the look of surprise in the babies face. This illusion is called object permanence. We expect things to be where they were, whether we see them or not, and are surprised when they aren’t. This is the primary tool of the stage magician – distract you and mess with your object permanence.


We humans tend to apply the laws of motions physics to people in an attempt at something close to object permanence. That is, we assume that people continue doing whatever it is we have seen them do before, even when we don’t see them directly or at all. This can make it hard for us to see when people are not doing as they have always done as we shortcut seeing what people are actually doing and assume that they are continuing as they always have. This can be quite devastating to those of us who wish to change, by the same token, we can expect that people will and have changed, when they haven’t, creating the reverse of the perceptual illusion with equally potentially devastating results. While we can save ourselves troubles by seeing what is really there, often this is not actually easy or possible, so we need to keep an open mind about what may truly be. This takes more effort and more resources, and in times of stress we don’t always have these.