Tuesday, July 31, 2012

How Our Brains Trick Us - Pareidolia

I am currently working as a TA for the Summer Science Program (SSP) which takes high school students that have been bored with their regular class work and show exceptional interest and talent in math or science and gives them five and a half weeks of lectures in astronomy, physics, computer science, and calculus, alongside a project to track and determine the orbit of a near Earth asteroid.  All of the TAs are allowed to give a guest lecture during the program.  I decided to do mine on a few of the ways our brains trick us.  This post will focus on pareidolia, with the other examples from my lecture to follow in later posts.  Some of the larger effects that I draw out from individual phenomena are actually the result of multiple psychological and biological factors working together.  I have still included them as examples because they are at least partially caused by the brain trick I am exploring.  There are too many logical fallacies and human biases to cover all of them in a 50 minute lecture.

While I have not done any original research on this topic (yet!), I’ve found that I am very interested in skepticism and critical thinking and what happens when we have a lack thereof.     The scientific method has critical thinking built into it.  It mandates that we must make our hypotheses before we see our data and that we use the rules of statistics and probability to interpret our data.  Common practices such as double-blinded studies help minimize the effect human biases have on experimental results.  But what happens once we leave the laboratory?  Surely our brains don’t stop being biased.  They don’t stop interpreting things subjectively.  How are they tricking us when we stop paying attention?

One example of our brains tricking us is “pareidolia,” the phenomenon of seeing patterns in random noise.  Our brains are excellent at pattern recognition, and, generally, this is a good thing.  It lets us learn languages, play music, do science and math, make art, and develop social skills.  But our brains overdo it.  They see patterns where ever they can.  This may be a leftover evolutionary trait.  Back when we still had to worry about being eaten, if you heard a rustle in the tall savanna grass, you had better recognize the pattern that the last time and the time before that, a rustle in the grass meant there was a lion and you’d better run.  It is much better to accept a false positive in this case (I run away because I think there is a lion, but it was really just the wind rustling the grass) than a false negative (I stay because I figure it’s just the wind and end up being eaten by a lion).  So extending this grass rustling/lion pattern makes sense. 

Recognizing facial expression patterns is also very important.  If you want to get along with the people in your group, you have to know if they’re upset with you or happy or worried.  So our brains love to see faces.  They are looking for any piece of information that will tell them what is going on, if there is any danger, if anybody looks like they are angry.  That’s why when faced with pure random noise, our brains try so hard to find a clue about what is going on, and they start to see things that aren’t really there.  Bam!  Pareidolia.

What this leads to in the wider scheme of things is cultural beliefs in things like Bigfoot, aliens, and ghosts.  One famous example of pareidolia is the “Face on Mars.”  

(Image from Wikipedia)

In 1976, the spacecraft Viking I took an image of a Martian rock outcropping that resembles a face.  Some people interpret this as evidence for intelligent life on Mars.  Others might recognize that seeing such a pattern in Martian rocks is just a result of pareidolia and our brains’ tendency to see faces when none are there.

More recently, the Mars rover, Spirit, took an image of a Martian rock formation that resembles a large, hairy, upright walking ape.  

(Image from abclocal.go.com)

This is claimed to be evidence of Bigfoot on Mars.  Such patterns tend to disappear once images are taken with better equipment or from a different angle.  When the Face on Mars was imaged again in 2001 by the Mars Global Surveyor, it's facial features are no longer visible.

(Image from http://www.msss.com/)


Pareidolia also gives us Jesus toast, Jesus tortillas, (Jesus anything, really), Homer Simpson on Mercury.

(Images are from (left to right) skepticmoney.com, skeptico.blogs.com, theness.com/neurologicablog)

Our brains can make faces out of pretty much anything...

(All images from geekosystem.com)

There is also auditory pareidolia.  Our brains gather information from the sounds around us, so they are also expecting auditory patterns.  This leads to exciting results such as listening to clips from skeptoid.com of arbitrary sine waves which sound like nothing at first

But once we are given a suggestion of what could be there

And listen to the original clip again

We start to hear patterns, intelligible speech, that wasn’t there before.  All our brains need is a little bit of a clue as to what we might be hearing in that random bit of noise and that’s enough for them to latch on to a pattern.  Our brains will take any bit of information they can get to make sense of the world around us, even if it means constructing an artificially ordered world.

But now that you know it happens, you can take care not to fall into the same trap.  Just as you wouldn’t think that because a cloud is in the shape of a bunny rabbit, it is actually a bunny rabbit, you need not think that because there appears to be what looks like Bigfoot on Mars, it is actually Bigfoot on Mars. And not all rock musicians have secret messages to Satan that can be revealed by playing their songs backward.

But sometimes Darth Vader really is on your toast:

(Image from coolest-gadgets.com)


  1. Great post, Joanna! I shared it on my blog:


    I hope this is okay. I already received some good comments via Facebook.

    Keep the posts coming. I'm really thrilled that you've continued writing after Ay20.

    And yes, sometimes Darth Vader is, indeed, on my toast