Your Brain is Playing Tricks on You (Part 1): Visual Illusions

Falling in love is an incredible feeling, isn’t it? One we don’t tend to forget very quickly. At least, that’s how it was for me and Neuroscience. I remember clearly when the falling in love started to take place. Junior year in college, reading a book called  by V.S. Ramachadran, Phantoms in the Brain: Probing the Mysteries of the Human Mind,
for my Neuroanatomy and Physiology of Human Movement class. I remember being glued to that book from cover to cover, only stopping briefly to write down a quick quote or call my parents to tell them the amazing piece of information I just learned (Yes, I still call them to tell them fun things like that :))

The amazing thing, that I’m sure you are realizing too, is that our brains are simply incredible. We have the ability to take in millions of tiny pieces of information in microseconds, integrate it within everything we believe to be true about our world and the universe and then make decisions on what that information means. It’s incredible, really. But did you know that this ultimate perception can lead to misinformation? Did you know your brain can really really mess with you?

Optical Illusions

One of the most well-known tricks of the brain is an optical illusion. Do you see a bunny or a duck?

Illusions DuckBunny

Which square is darker, A or B? (They’re actually the same color!)


By Wuhazet – Henryk Żychowski (Own work) [GFDL ( or CC BY 3.0 (, via Wikimedia Commons

So, how did your brain trick you? Your nervous system is constantly gathering information about the body and the environment through multiple different inputs: visual, mechanical, temperature, proprioceptive (the position of your joints), vestibular (your inner ear). This process is called sensation. Perception, then, is your brain’s interpretation of the information it receives. The brain receives and filters the information from various sensors and then interprets its meaning to create our experience. In these cases, your brain receives the signal (visual input) and then perceives meaning based on the information, and your experience. In the first picture, your brain likely can see either a duck or a bunny depending on how it chooses to interpret the information. In the second one, your brain took into account the shadow that the green cylinder was casting on the board– thus, your brain tricked you into thinking that tile B must be lighter than tile A (although, really they are the same!) And the third one, your brain saw the arrows in the first one as narrowing in the space, and the second as expanding it–even though the lines are the same length. Pretty cool, right?!

Magic Tricks 

I have always loved a good magic trick. I remember seeing my first “real” magic show in Las Vegas at Harrah’s Casino. I was 11 or 12 I think, and was completely mesmerized by Mac King and his comedy magic show. My family just loved it! We were amazed, and couldn’t figure out how he did what he did.

(This is actually pretty close to what that magic show looked and felt like–so enjoy being transported back to 12-year old Jessica’s life!) 

I still love watching a great magic show. From street magicians like David Blaine to bigger than life magicians like David Copperfield or Siegfried and Roy, magicians have the ability to suspend our belief, challenge our perceptions and allow us to believe we are seeing the impossible.

So what are magic tricks? How do they feel so “real” to us watching?

In a way, magic tricks are very similar to optical illusions. Magicians are truly masters at using the brain to fool us into truly seeing something that did not happen. Magic tricks work based on several key principles. First, as we discussed above, your brain constantly creates perceptions based on the sensory inputs it receives from the environment. As was shown in our “illusions” section, the perception does not always directly match the visual input as our brain integrates vision with our previous knowledge, emotions, experiences, etc. to make predictions and ultimately create perception. These predictions are precisely what is exploited during magic tricks. This great article gives the example of the “vanishing ball” trick. In this trick, the magician throws the ball up in the air several times, and finally on the last one, the ball appears to vanish out of the air. But did it really vanish? Of course not! The magician used our brain’s predictions in his favor…thus, we saw the magician continuing to look up toward the ball, we saw the hand move in a “throwing pattern.” and the brain cut a few corners to tell us the ball had been thrown! While we’re busy watching that magician’s face, the ball is then palmed away, and our brain perceives it has vanished! Pretty cool, right? (check out the article for a larger, more detailed explanation!)

Magic tricks also work by confusing our brain with conflicting inputs and playing with our attention. For example, we are much more easily tricked and distracted when we have to multitask and focus on multiple different things at once. This is common with card tricks and other illusions. Emotions (such as humor, story-telling, etc) can also lead to some brain-trickery as it again creates a distraction for the brain, forcing the brain to “predict” to fill in the missing pieces.

It’s really, quite incredible, and learning about all of this actually has made me respect magicians even more as fellow neuroscientists! Check out these excellent articles if you want to dive a little deeper and further understand more of what happens with magic tricks!

Now…You may be thinking… “What the heck Jessica? This is a “pelvic-focused” blog! Why are you writing about optical illusions and magic tricks!?” Well my dear blog reader, you’ll have to find out… Stay tuned for Part 2- Your Brain is Playing Tricks on You: Pain


2 responses to “Your Brain is Playing Tricks on You (Part 1): Visual Illusions

  1. stephanichristian

    Hey Jess! I just found your blog as I was doing some googling about pelvic PT! I just started doing Pelvic PT about 2 years ago. The hospital where I work needed a program and I was the only therapist willing to start one up! Right now I’m doing outpatient ortho 3 days/week and pelvic PT 2 days/week. So glad to see you are doing well and I will definitely start following your blog!

    -Stephani Christian (formerly Mathews, fellow duke 2010 grad 🙂


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