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Your Deceptive Mind: A Scientific Guide to Critical Thinking – Part 3



Your Deceptive Mind

This article is part three of an in-depth summary of the brilliant course:

Your Deceptive Mind: A Scientific Guide to Critical Thinking 

In this article:

  • Why seeing isn’t believing
  • Why you can’t trust anything you think you see or perceive
  • Attentional blindness
  • Change blindness
  • Optical illusions
  • The McGurk effect
  • and more…

Let’s begin:

TWA Flight 800

In July 17, 1996, TWA Flight 800 crashed shortly after takeoff. There were many eye witnesses who reported seeing a missile or a streak of light going into the plane. However, an exhausted FBI and National Transportation Safety Board investigation concluded that there was no missile.

Therefore, what did all of those eye witnesses see?

The red panda

In 1978 a red panda escaped from the rotterdam zoo. The story of the escaped panda ran in the local papers following which there were hundreds of red panda sightings all over the city. However, it was soon discovered that the panda was killed just outside the zoo, and that it had died prior to the story and all of the sightings.

So what did all of those hundreds of eye witnesses see? It could not have been a red panda.

Is seeing believing?

Is seeing believing?

It’s actually more accurate to say that believing is seeing.

The truth is you cannot trust anything you think you see or perceive. There are simply too many flaws in the ways our brain constructs these perceptions.

Our perceptions are not passive. It’s not like a tape recorder or a film camera where the details are recorded as they come in. In fact, our brains actively construct a picture of what is going on around us based upon on a tiny fraction of all the sensory information that’s coming in, which introduces many opportunities for distortions and error.

Over centuries, magicians have learned how to exploit the foibles of the brain’s sensory processing. They have developed a practical knowledge of how to decieve you, how to do things right in front of your face without you seeing or perceiving that these things occurred. They use this knowledge for entertainment, but it is possible for these same tricks to be used for nefarious purposes.

Artists have also learned how to exploit the ways in which our brain processes information in order to create special effects. For example, they have developed laws of perspective and dimensionality, resulting in the ability to create a three-dimensional image on a two-dimensional canvas.

Optical illusions

Perhaps the simplest demonstration of the constructed aspect of our sensory input is optical illusions. By definition, all types of illusions occur when the brain constructs sensory perception in an incorrect way, causing a misperception of reality.

Generally, objects in our world appear to be stable and accurate with respect to reality. Psychologists refer to this property as constancy.

Optical illusions, by definition, represent an exception to constancy—a time when objects either are not stable or do not accord with reality. There is some kind of internal inconsistency or paradox in what we think we are seeing. This is because the brain has to make assumptions about what’s likely to be true, and then it processes the sensory information based on those assumptions. Most of the time, those assumptions are correct; when they’re not correct, that results in an optical illusion.

Seeing what’s not there

Nobody is immune to optical illusions, so even being a trained pilot or observer does not make your brain construct things differently.

For example, in 1997 a military helicopter reported seeing what they thought was another aircraft that was about to collide with them. They took evasive action.

However, it turned out that what they were viewing was simply a small metallic mylar balloon. The trained pilot who you would assume would be able to tell the difference between an aircraft and a balloon, was unable to do so. His brain made wrong assumptions about distance, and everything else flowed from there. Your brain could see the object as being far away, large, and moving very rapidly, or it could see it as close, small, and moving very slowly. Your brain can construct it either way. The pilot thought he was seeing a large, aircraft moving quickly towards him, when in fact it was a small balloon just drifting by.

Another “UFO”

Another example in Stephenville, Texas, on January 8, 2008, witnesses saw a UFO that they reported was one mile long. Investigations revealed however, that what they were seeing were actually flares that were dropped by F-16s and that the witnesses constructed the UFO by connecting the dots of light.

This is something that our brains do when it’s constructing our perception of the world around us, it will fill in lines or connections where it thinks they should be based on assumptions about what it thinks it’s seeing. In this case three disconnected dots were perceived as being part of one massive mile long object.

The battle of Los Angeles

Another example of how it’s possible to see something that isn’t there simply because of the situation, is the battle of Los Angeles

This is the air raid over Los Angeles, California, that took place on February 25, 1942, during which over 1,400 anti-aircraft shells were fired. Eventually, it was concluded that the entire air raid was simply a false alarm, and was probably the result of war nerves towards the beginning of WWII. It might have been triggered by something as innocuous as a weather balloon.

However, because it was the beginning of World War II, once these shells started to fire, the soldiers who were manning these anti-aircraft guns were firing these shells at something, they thought they were seeing planes invading the west coast of the United States.

Difference senses influence each other

Another dramatic example of how our brains construct pictures in our heads from available sensory input is the fact that the different senses can actually influence each other. Our brains will compare different types of sensory input in order to construct one seamless picture out of all of them, and it will adjust one sense or the other in order to make things match.

Wine snobs fooled

One example of this is the 2001 wine test by Frédéric Brochet where he colored white wine with red food coloring. He then gave the “red wine” to wine tasting experts and asked them to describe what they were tasting. The experts described the white wine as if it were a red wine, their very highly developed and sophisticated wine tasting sense was fooled merely by the color of the wine they thought they were drinking.

Cheap vs expensive wine

In a related study Frédéric Brochet placed the same exact wine into different bottles, with either cheap or expensive labels. Wine tasting experts were then asked to compare the different wines and rate them. They rated the wine with the expensive label in glowing terms, while denigrating the same exact wine with the cheap label as unworthy.

Here we can see how perception can be greatly influenced by expectation even among experts.

The McGurk effect

Another example of how our brain uses different types of sensory input in order to construct its picture is the McGurk effect which describes the fact that what we hear is dramatically influenced by the mouth movements that we see.

Our brain adjusts the sound in order to make it congruous with the lip movements you see, so you actually hear different consonants when this is happening.

This is another dramatic example of how our brains modify, author and construct our sensory input.

Temporal synchronization

There is also temporal synchronization. Activities that combine sounds and sights, such as clapping hands, seem to be simultaneous, but the light traveling from someone clapping their hands travels much faster than the sound waves propagate. Therefore, the two sensory inputs do not arrive at your sensory organs at exactly the same time. It also takes slightly different amounts of time for your brain to process those two types of information.

However, when we look at someone clapping their hands, the two events appear to be simultaneous. That however, is a constructed illusion in your brain. Your brain synchronizes the two events because it knows that they’re supposed to occur at the same time. In fact, as long as the visual and auditory information are within 80 milliseconds of each other, your brain will perceive them as being simultaneous.

Paying attention to sensory information

Attention is immensely important to perception because we are constantly bombarded with an overwhelming amount of sensory information, and we cannot possibly pay attention to even a significant fraction of it—let alone all of it—at the same time. We filter out most sensory information that reaches us and pay attention to only what our brains deem to be important.

In some experiments of attention, subjects watch a video and are instructed to focus on one type of activity that’s occurring in the video while at the same time, something else very dramatic is happening in the video right before their eyes. About 60% of people who watch the video are completely unaware of the dramatic events occurring right before their eyes simply because they were instructed to attend to a different part of the video.

Inattentional blindness

In fact, only the center of our visual field is highly detailed. If you hold out your thumb at arms length, the size of your thumb is about the area where you have 20/20 vision if your vision is normal and healthy. Everywhere else you have extremely poor vision. You can’t pay attention to every part of your peripheral field at the same time. Inattentional blindness describes the notion that we are blind to things that we are not attending to.

Change blindness

There is another closely related phenomenon called change blindness, where we do not notice sometimes even dramatic changes that happen in our environment.

For example, several experiments show that when interacting with an unfamiliar person, someone you don’t know personally, that person can change outside of your view and about 60% of the time subjects won’t notice that they’re talking to an entirely different person than they were just a moment ago before the swap. Even a dramatic change such as that, changing one person to another, can escape our noticing.


An example of our ability to only attend to a small number of things at the same time is multitasking. The term multitasking is used to define doing more than one thing at the same time, but research shows however that people can’t do this, we can’t attend to more than one thing at the same time.

What people do when they’re multitasking is they shift their attention back and forth between or among the things that they’re doing. But they can only give attention to only one thing at a time.

In experiments, only 2.5% of people are able to talk and drive at the same time without a reduction in their driving performance. That’s a very small number. Everyone else has a significant decrease in their driving performance. That’s why it’s not a good idea to talk on your phone whilst driving, and why many states have laws that prohibit it.

Eyewitness testimony is notoriously unreliable

Eyewitness testimony is also notoriously unreliable. Eyewitnesses are subject to suggestion, they have a false confidence in their own
accuracy, and they’re subject to confabulation, or making up details.

Our brains construct a narrative, a story, a consistent reality out of what it thinks it perceives ,and part of that construction involves subconsciously filling in missing pieces. That’s called confabulation, and this is done subconsciously and automatically, and people will think that these pieces that they added were perceived, that they were actually out there in reality.

Perception is a construct

Perception is a construct. That’s the bottom line lesson here. It is something that is happening inside your brain. Each individual sensory stream is interpreted and modified, the different streams are then combined, compared, and then altered based on that comparison. We attend to a very small subset of that information, which we weave into a complete story by adding confabulating pieces as needed. The end result is a story that is largely fiction.

If we understand the limits of our perceptions, then we will not overly rely upon them. Instead of saying, “Hey I saw it with my own eyes seeing is believing!”, we’ll say, “I think I saw this, but honestly I don’t know, and I can’t really know exactly what I saw because it was something that was constructed by my brain.”


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