senses behavior attention survival

You Can't Observe A Lot Just By Watching

“Are you watching closely? Abracadabra.” How magicians use our brains against us.

How do magicians do magic? Have they been touched by sparkly fairy powder or found the end of the rainbow? What do they do in order to perform a trick? They divert your attention to buy time for the magic to happen. Ready for a little experiment? Follow the instructions on this video.

This video is a well-known experiment performed by Daniel Simons and Christopher Chabris. They showed the video to participants to study how people react to changes in the visual field and how visual attention works (or doesn’t). Simons himself reflects how amazing it is given that “Although 90% of people are convinced they would notice the gorilla, only 50% actually do” [1].

What is going on? Your attention might not be working as you would think it should. Let’s go back to the magic. A good trick needs a compelling story behind and it also needs to make you focus. It doesn’t matter if you’re trying to discover the trap or just enjoying the ride. You will be swung through the inner mechanism of the tale until, surprise, abracadabra. And the magician knows it.


Fig 1. Animation extracted from The Prestige (link Edited by Matias Andina.

The magician moves the coin because your brain is attracted to movement [2]. He talks to you to illicit your auditory channel, to center your attention where he wants. Why? Why does he need you to be so involved in the story? The magician tests your focus, reinforcing the fact that you must pay attention to something completely irrelevant. By doing so, he focuses all your brain energies into the distractor. When you stare directly at it, you lose resolution of everything else.


Fig 2. Magicians prompt us, challenge us, divert our attention using every sensory channel they can. Image from “The Prestige”, edited by Matias Andina.

Fixating our eyes is the way we see the world in super resolution. Scientists use the term foveation, because the word is fancy and the fovea is the place in the retina that has the best resolution. Everything else we see outside this zone will suffer from a blunt loss of information. Fig 3 shows you an exaggerated example of what you actually perceive. If you keep your eyes fixed at the coin, it is hard to tell the artwork on the magician’s ring or which finger it is on.


Fig 3. Example of foveated image. Both the focus and blur are exaggerated, normally you would perceive it smoother. The actual foveated image depends on many real distances (your fovea size, distance between your eyes and the monitor, etc.). Edited by Matias Andina.

Here’s another example of how different competing stimulations can mess with our perception depending on where you direct your attention.

Is this going to be on the test? Phenomena like these are found in everyday life. If you grab a blender and mix 2 parts of perception attentional modulation, with 3 parts competing stimuli (noises, odors, …) and one big emotional event, you can create a very distorted reality that will be stored as a false memory. False memories are recollections of events that did not happen. I’m OK remembering the time when I discovered teleportation, but when you need someone to testify whether a car ran into the intersection during a red light or identify faces in a prison lineup, false memories can cause big problems [3].


Fig 4. Image taken from “The Usual Suspects” ( Edited by Matias Andina.

I really like how deep – yet beautifully simple – Yogi Berra’s quote is: “You can observe a lot just by watching”. I titled this article in the opposite direction because I wanted to emphasize that it’s not enough to observe, no matter whether it’s a magic trick or a crime scene. Our brains have more intricate and sometimes colliding mechanisms to interpret the world through the projections of our senses. I wonder if Yogi Berra would say the same, now that we know that parts of what we perceive (and remember) might not be real.

Note: Throughout the article I used a loose, non-scientific, definition of attention. I also used brain energies, focus and other terms/analogies to refer to attentional processes. Attention itself is an abstract topic that escapes the aims of this post. My main intention was to bring the reader into the world of attentional modulation of perception and open the door into the unknown for those brave investigators who dare to satiate their need for knowledge.

References: [1] [2] Abrams, R. A., and S. E. Christ. “Motion Onset Captures Attention.” Psychological Science 14, no. 5 (2003): 427-32. doi:10.1111/1467-9280.01458. [3]

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