This Optical Illusion Lets You See Your Own Brain Waves

This Optical Illusion Lets You See Your Own Brain Waves

The pinwheel-like drawing above is nothing but black and white lines. When you look at it the right way though, something strange and beautiful happens: it begins to flicker. You may think it's just a regular old optical illusion at first, but actually, you're looking at your very own brain waves.

To see the optical illusion takes a little bit of work. Look at the pinwheel shape and then stare at a spot that's just a few inches away from it. When the pinwheel is in your peripheral vision, you should start to see the center flicker, kind of like a really bright star does. The effect also works as an afterimage. So once you find a spot that gets the flicker going, stare at it for about a minute and then look at a blank white wall. You'll see the inverse image of the pinwheel, flicker and all.

In a new paper, neuroscientists Rodika Sokoliuk and Rufin VanRullen argue that the flicker you're seeing is actually a physical manifestation of your brain's alpha waves. Alpha waves were the first neural oscillations detected by Hans Berger, the inventor of electroencephalography (EEG) — hence the name "alpha" — and represent rhythmic changes in brain activity. Typically, they cycle at a rate of about 10 Hz, or 10 times a second. That frequency is partly how Sokoliuk and VanRullen made the connection between the flicker and the alpha waves. Asked to compare an artificial flicker with the one in the pinwheel, most subjects of their study selected one with a frequency of 9.1 Hz.

The frequencies matching could be a coincidence, but Sokoliuk and VanRullen also found a direct correlation between subject's alpha wave activity and the presence of the flicker. They explain in the paper's abstract:

The occipital alpha rhythm of the EEG was the only oscillation that showed a time course compatible with the reported illusion: when alpha amplitude was strong, the probability of reporting illusory flicker increased. The peak oscillatory frequency for these flicker-induced modulations was significantly correlated, on a subject-by-subject basis, with the individual α frequency measured during rest, in the absence of visual stimulation.

Pretty cool, right? In a way, the pinwheel serves as a nice reminder that our brains are still working. At least they are for most of us. [Discover]

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    What did I tell you about animated GIFs? That flicker will give someone a fit!

      that flicker is just my monitors refresh rate :P

      The rate at which the after image flickers is probably affected by the number and thickness of the surrounding gratings. Would be cool to see if they also get alpha waves to similar stimuli (different number and thickness of gratings) or whether they get oscillations in different frequency bands. If it is true that they get alpha oscillations for all similar stimuli, then it might be a physical manifestation of alpha waves. That said you might be able to say the same about many other optical illusions with motion after effects. Cool study though

    I got nothing....guess Im off to the hospital to tell them my brain has stopped working.....if IM lucky I might get to meet the people IM going to give my organs too.......

      I think im at the other end of the radar bro,
      im seeing the 'spoked' image, but colourful swirls radiating from the center, almost looks like a flower...
      yeh, I think I will meet you at the hospital too...

    Owww, Migraine.
    You bastards.

    Please show an illusion that makes real money fall into my hands. I love money.

    It's not like this phenomenon in itself is new. I remember being sent various images by email, such as this classic ( back in the '90s or early 2000s, before there was a website for everything.

    It's interesting that it only works in peripheral vision, but it's also interesting to have a possible explanation for this effect.

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