Let’s start with a simple yet somewhat counterintuitive truth: we don’t see the world as it is, we see the world as it is useful for us (from an evolutionary perspective).
Our brain works like a filter lens. It filters reality in such a way that makes us aware of certain elements around us that are useful to us (for our survival generally or in a particular situation) and unaware of other elements that are less useful.
This means that our brain does not work like a camcorder – it does not passively receive sensory information. Rather, it dynamically shapes what we perceive with our senses through the lens of evolutionary biology – for our survival, generally – and through the lens of cognition (memories, emotions, judgements, intentions) contextually.
Here are 6 surprising facts about how we perceive the world around us:
#6 – Color vision: why do we see in color?
However we look at it, our vision is limited. We can only see light of wavelengths from about 390nm to 750nm on the electromagnetic spectrum. The other wavelengths are still there, but our eyes simply cannot detect them.
Yet, our eyes are able not only to detect wavelengths on that particular range of the electromagnetic spectrum, they are also able to differentiate between wavelengths in that range. This capacity to differentiate between electromagnetic radiation of different wavelengths is what gives us color vision.
What we have to remember, though, is that colors do not exist in the physical world. There are just electromagnetic waves of different wavelengths. Colors are the product of the way our eyes and brain perceive the world.
As humans, we are trichromats, which means we have three types of color-sensitive cone cells in our eyes that allow us to differentiate between the different wavelengths of light. Of all placental mammals, only primates and most species of New World monkeys are trichromates. Most other mammals are dichromats – they have two types of color-sensitive cone cells, which make them only see colors on the yellow-blue spectrum.
Why is this significant? Think for a moment about the tiger’s orange coat. Surely it would make the tiger easily stand out among the green of the jungle! However, you have to remember that when we (as Trichromats) see this:
most other mammals see this:
What all these trichromats have in common is that they are highly social animals. So can trichromacy be somehow related to this? In fact, it does. According to Dr. Mark Changizi, what is also common to trichromat primates is exposed facial skin (ie. faces not covered with fur). When the skin is exposed, these primates can communicate their emotional state based on the level of hemoglobin and oxygen in the blood. A green hue of the skin usually indicates sickness (low hemoglobin, oxygen), red indicates blushing or excitement (high hemoglobin, oxygen), blue – cold, lethargy (high hemoglobin concentration), and yellow – fear or bloodless (low hemoglobin concentration).
In other words, we see color not because color exists in the physical world but because color vision is useful for communication.
#5 – Hearing filter
Imagine yourself entering a relatively quiet room to read a book. As you come in you hear a clock ticking or the noise of crickets outside. Yet, within a few minutes, as you settle in your couch and start reading – and if the noise is not too pronounced – you no longer notice the noise. How is this possible? The noise is still there, yet you don’t notice it (unless you consciously make yourself aware of it again).
The reason for this phenomenon has to do with how the brain modulates attention and conserves energy. One of the primary functions of the brain is to maintain vigilance in the face of danger. The process goes like this: once a threat is detected the brain disengages from its current activity, the motor center physically reorients the body to direct the senses toward the threat. Then a cognitive assessment of the situation takes place, together with physiological arousal and reaction to the threat.
The problem is that this process – when activated – requires an enormous amount of mental energy. That is why as the brain monitors the environment for possible threats it must prevent false alarms. To do so the hippocampus compares incoming stimuli with past memories, and designates them as either novel or ordinary. If a stimulus is considered ordinary (clock ticking), and is not relevant to the task at hand (reading a book), the brain will filter out the noise and thus conserve mental energy.
#4 – Vision filter
If a “hearing filter” does not sound convincing, how about a “vision filter”?
Just as before, the concept behind the vision filter is that we cannot be aware of all the stimuli in our field of vision – ie. as a camcorder would record it. In other words, the brain filters what we see in such a way that we are mostly aware of those things that are useful to us – for survival, or for a particular purpose – and unaware of other things that are less useful (even though those things are within our field of vision).
There is a famous experiment called the Monkey Business Illusion which demonstrates this phenomenon well:
Nearly 40% of people who watch the video for the first time do not see that which is supposedly in plain sight! That number goes up to 80% when people are also asked to keep track of who’s passing the ball.
We’ve seen how our brain filters what we hear and see not based on what is actually out there but rather on what is useful for us in a particular situation. Next, we’ll see how our brain shapes what we see based on what we expect to see.
#3 – Predicting the future
Contrary to common wisdom, we do not see the world around us in “real-time.” In fact, about 0.1 of a second goes by from the time light hits the retina and the time our brain processes the signal into a visual perception.
A one-tenth of a second visual delay can create some serious problems in the real world; if an object flies at you at a speed of 10 m/s, it would hit you before you even notice it was a meter away. Conversely, if you are running (or driving) at a high speed, seeing things around you at a 0.1 second delay could easily lead to disastrous situations.
To compensate for this neural lag the brain projects where objects in the environment are likely to be one-tenth of a second into the future. In the real world, this mental projection usually corresponds to where objects actually are in the present. The following experiment demonstrates how this mechanism unravels in the virtual world:
Since the background is moving back and forth, the brain automatically projects where the box is expected to appear in relation to the background 0.1 seconds in the future. The difference between what the brain projects (ie. what we perceive) and what is actually happening creates this visual illusion.
But that’s not all. Scientists have discovered that if you are moving around in a familiar environment your brain would predict what it is likely to see based on previous experiences. Only when there is a significant difference between what you expect to see and what is actually there the visual cortex becomes more active in processing the information. Otherwise, the brain can conserve energy by relying on stored mental images.
#2 – Grounded cognition
Why does holding a hot drink make us perceive people as warm? Why does sitting in a hard chair make us more rigid in negotiations? Why does holding a heavy clipboard make us consider decisions as more important?
According to Neuroscientist Daniel Wolpert we have a brain “for one reason and one reason only — and that’s to produce adaptable and complex movements.” As humans evolved higher-level abstract thinking, such thinking utilized the same neural pathways as those used for physical sensations and movement. So, for example, when we think about getting something from the fridge the same neural pathways are activated as the physical actions involved in actually doing so.
Similarly, when we employ higher-level abstract thinking or metaphorical language these too are intimately related neurologically to concrete sensory or motor functions. In other words, our cognition is neurally grounded in bodily movements and sensations. So sensing temperature can trigger feelings of intimacy, weight to importance, cleanliness to morality, and so on.
Here Professor Lawrence Barsalou of Emory University explains Grounded Cognition:
#1 – Belief filter: the interpretor
So far we’ve seen that we have color vision not because there are colors in the real world but because it’s useful for communication. We’ve seen that our brain filters what we hear and see based on what is useful for us evolutionarily, and that we see the world not as it is but as our brain predicts it to be. We’ve also seen that how we interact with the environment shapes how we think.
Now let’s go a step further. We’ll show how people’s need to find answers to the most important questions of life has less to do with some spiritual search for meaning and more with the fact that we evolved a mechanism which actively interprets the phenomena we experience. In other words, we form beliefs about ourselves and the world around us because these beliefs are useful for our survival.
So what exactly is this mechanism? Dr. Michael S. Gazzaniga, in his article The Interpreter Within: The Glue of Conscious Experience, explains:
The answer appears to be that we have a specialized left-hemisphere system that my colleagues and I call the “interpreter.” This Interpreter is a device (or system or mechanism) that seeks explanations for why events occur. The advantage of having such a system is obvious. By going beyond simply observing contiguous events to asking why they happened, a brain can cope with such events more effectively should they happen again.
Yet, the answers we seek do not have to be based in reality. They merely have to be consistent with our experiences and perception…
We revealed the Interpreter in an experiment using a “simultaneous concept test.” The split-brain patient is shown two pictures, one presented exclusively to his left hemisphere, one exclusively to his right. He is then asked to choose from an array of pictures the ones he associates with the pictures that were presented (or “lateralized”) to his left brain and his right brain. In one example of this, a picture of a chicken claw was ﬂashed to the left hemisphere and a picture of a snow scene to the right. Of the array of pictures then placed in front of the subject, the obviously correct association was a chicken for the chicken claw and a shovel for the snow scene. Split-brain subject Case One did respond by choosing the shovel with his left hand and the chicken with his right. Thus each hemisphere picked the correct answer. Now the experimenter asked the left-speaking hemisphere why those objects were picked. (Remember, it would only know why the left hemisphere had picked the shovel; it would not know why the disconnected right brain had picked the shovel.) His left hemisphere replied, “Oh, that’s simple. The chicken claw goes with the chicken, and you need a shovel to clean out the chicken shed.” In other words, the left brain, observing the left hand’s response, interprets the response in a context consistent with its own sphere of knowledge—one that does not include information about the snow scene presented to the other side of the brain.