Friday, September 18, 2015

The McCollough Effect

Note: I'm going to postpone the next book club until the first week of November 
because I've got a lot of traveling coming up in October. 

Optical illusions that produce colored afterimages are fairly common, but there's afterimage phenomenon that's so long-lasting that I won't show the induction image directly on the blog.

It's called the McCollough Effect, and it's basically a pattern of black, red, and green bars. Staring at them for more than a few minutes can lead to afterimages that strangely last for days. Ten minutes of looking at it can affect your vision for 24 hours.

In this video (Link to YouTube video), Tom Scott introduces the phenomenon. The video is safe to watch because the exposure to the image is too brief to cause induction.

On this MoviePilot website you can read an informal description about how it works. Here's a more scholarly presentation. If you want to try it, you can follow instructions on the MoviePilot page or on this flash video presentation

But—warning—please only try it if you're willing to experience the colored afterimages for hours, days, or even weeks.

I haven't tried it because I'm in the middle of a painting right now. If you decide to give it a try, please share your experience in the comments. I wonder if red-green colorblind people would see any effect. I'm told that the effect can be reversed by gazing at the original induction image, rotated 90Âș counterclockwise for half of the time that you spent looking during the initial induction.
MoviePilot website to see the image
Flash video presentation on a Boston University site that induces the illusion.
Via Design Taxi "This Image Can ‘Break Your Brain’, Change The Way Your Mind Works
McCollough Effect on Scholarpedia -- For scholarly analysis of the phenomenon.

Note: I'm going to delay the next GJ book club about Harold Speed's book on painting until the first week of November because I've got a lot of traveling coming up in October.


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Sam Borg said...

If any of you still want to try it but are afraid of your painting career taking a three month nosedive, from what I've read and observed, this illusion seems to be completely dependent on the super-specific stimuli of something lined to the same orientation and relative spacial properties of the original induction images. The after-image will actually dissipate if you look at the affected images turn your head 45 degrees and even reappear if you go the full 90! Although you might get an initial, white square in your vision that goes away fairly quickly, you shouldn't have a color after effect unless you start looking at black and white lined images that closely resemble the red and green ones in terms of line spacing. If you do it for just a minute or two you can get the effect very lightly. It shouldn't affect anything major.

I think the above info is what actually makes this illusion so cool. You get to watch your brain interact with a visual cue and adapt to these expectations in real time. It's reminiscent of the Blakemore and Cooper kitten experiment, where they used intense visual conditioning to make kittens actually not able to perceive lines oriented a certain way. There's a great demonstration video of the experiment on Youtube for those interested.

MoStarkey said...

Like you, I'm in the middle of a project and I know I'm sensitive to this sort of thing. So I won't go exploring this too soon. But it was great to see it has an actual name. When I was in college I played with color patterning and got similar effects. I knew I was on the right track when the pattern vibrated and I felt like throwing up. You can get some neat illusions and it's worth experimenting. But you want to be careful.

Sizun said...

I once stared at a red trafic light a bit too intently and when I turned my head to the white truck along my car I saw a green spot on it. This spot remained for some time, although certainly not the whole day...