How optical illusions may help diagnose autism

Check out this simple optical illusion:

Watching this illusion, it appears like a spinning cylinder. In reality, it is two columns of dots moving in opposite directions. There is no curve, no spinning, no roundness at all. Just black dots moving one way and white dots the other.

However, your brain isn’t looking at the dots. Your brain just sees the big picture. That’s what your brain does: it takes all the data and stimuli that it receives from your senses and creates an image of the world.

And sometimes, like with this illusion, that image is wrong.

It is our brains greatest strength and greatest weakness. On the one hand, our brain is capable of constructing complex images from a multitude of datum. On the other hand, those images can be misleading.

Magicians use this quirk of neuroscience to deceive audiences. We rely on the fact that your brain will assume that if it saw a coin go into your left hand then there really is a coin there. Audiences will swear they saw a coin in a hand that never even had a coin in it.

Now, that same quirk could be used to diagnose autism. According to the researchers behind the illusion, people with autism view the cylinder in a very different way.

“Everybody reports the spontaneous and unpredictable changes in the cylinder’s direction,” says Professor Burr from the University of Sydney in an interview with the Sydney Morning Herald. “But not everyone perceives the figure in the same way.”

People with autism have a tendency to focus on detail rather than the big picture. This explains why they often spot minor details others miss but are completely unaware of larger, more complex systems such as social cues.

They may notice that you have worn the same shirt four times this week but they won’t notice that it annoys you when they keep pointing it out.

According to Burr’s research, people who score higher on tests for autism are less likely to see the cylinder.

Of course, it isn’t as simple as putting kids in front of an optical illusion and measuring the odds of them showing up on the autism spectrum.

“This is not a particularly strong study,” says Professor Cheryl Dissanayake of the Olga Tennison Autism Research Centre. "It’s not even talking about an autistic population"

A 2010 study suggests people with autism have a more complex relationship with illusion. In the study, people with autism were more likely to be fooled by magic tricks that rely on reading social cues, the opposite of what you would imagine. It is a fascinating study and well worth checking out.

Or maybe the researchers are finding patterns where they don’t really exist….

For more information on the science of deception, check out Deceptology.

Nicholas J. Johnson is a Melbourne magician and author.

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