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April 10, 2004 10:51 AM   Subscribe

The McCollough effect is a visual illusion somewhat similar to regular color aftereffects, but the working mechanism is different, and despite a wealth of theories, not entirely explained. Once the effect is established, it does not seem to go away and can last for days or even weeks. Proceed at your own risk.
posted by ikalliom (22 comments total)
this sort of thing is why snow crash will kill us all in the end. I love it.
posted by dorian at 11:25 AM on April 10, 2004

That's kind of creepy; I saw the bars as red and green before I even looked at the extra image. Maybe it's time to cut back on the Cocola.
posted by headspace at 11:39 AM on April 10, 2004

posted by ROU_Xenophobe at 11:53 AM on April 10, 2004

Blit was fun reading, thanks
posted by roboto at 12:45 PM on April 10, 2004

i don't know why, but i looked at part 1, and read the entire thing before clicking the colored part, and when i scrolled back up to the black and white--without having seen the colored part--it had already worked for me. ??
posted by ifjuly at 12:48 PM on April 10, 2004

Same here. The horizontal lines were pre-coloured magenta (I guess, magenta's not in a box of crayolas so it's not a real colour!). Though the vertical stripes were solid black. After staring at the coloured tiles I saw a green haze around the horizontals but the vertical stripes were still black.
posted by substrate at 1:19 PM on April 10, 2004

It's weird that anyone had pre-coloring (maybe expectation can influence the effect?) but after just 2 minutes or so I'm still seeing green around the horizontal lines 2 hours later.
posted by abcde at 1:31 PM on April 10, 2004

I used to get this effect when i looked at smallish tile patterns (like those found in bathrooms, etc.) as a kid. Nobody else saw it, and my parents thought I was crazy.

As it turns out, I'm not.
posted by zpousman at 2:21 PM on April 10, 2004

I got the green haze, but not magenta, even after repeated tries. Did anyone else have a similar response?
posted by F Mackenzie at 2:38 PM on April 10, 2004

I saw colors from the start, too. Before I looked at the colored grids, the vertical lines looked deep red but my brain didn't know what to do with the horizontal lines--first they were very dark green, then black, then dark blue-green. After looking at the colored grid both sets of lines were brighter and more steadily colored.

Two hours later: The horizontal lines are still as green as they were, but the vertical lines have faded back to the very deep red I saw before looking at the colored grids.
posted by hippugeek at 2:57 PM on April 10, 2004

F Mackenzie: Same.
posted by abcde at 2:59 PM on April 10, 2004

Cool link. Thanks!
posted by jeblis at 3:24 PM on April 10, 2004

The folks seeing it automatically may be suffering from monitor mis-calibration. Print it out and try again...
posted by daver at 3:48 PM on April 10, 2004

I didn't see any colors from the start. After looking at the colored versions for one minute I didn't notice any change, really. But after two minutes I flipped back and the green haze was there. It took three minutes of exposure for me to see the purple haze.*

*Ironically, the Jimmy Hendrix song is 2:50 - coincidence? :-)
posted by stevis at 3:56 PM on April 10, 2004

Three minutes, got nothin'. Maybe I'm just that much of an introvert. Whatever, you people are wearing me out.
posted by Eamon at 7:19 PM on April 10, 2004

This is the best illusion link I've ever found.
posted by snarfodox at 10:59 PM on April 10, 2004

As for those with "pre-coloring" even before knowing what to expect: could be related to Synesthesia. Though the more intense forms of synesthesia are fairly rare, several studies have shown less severe 'blending' in varied levels to occur more widely.

When I was at UCB, one of my friends was a synesthete involved in a study under Vilayanur S. Ramachandran. The study had to do primarily with color-character association, but also delved a little deeper into intersensual combinations (seeing sounds, the texture and shape of colors, etc).
posted by quasistoic at 5:23 AM on April 11, 2004

Wow. 16 hours later and the haze is just as strong. Creepy.
posted by stevis at 7:45 AM on April 11, 2004

Moooowhahaha! I wasn't so naive as to actually look at it! You are now all under aLiEnMiNdCoNtRoL! Into the sausage-grinder you go!
posted by five fresh fish at 9:29 AM on April 11, 2004

I didn't see anything, which was kind of disappointing. And I'm fatigued and wearing half-dried-out contact lenses right now, but still, nada.

But the page does say "The duration can be changed by the consumption of coffee and other psychoactive drugs", so maybe that's a factor.
posted by Asparagirl at 11:19 PM on April 11, 2004

i stared at those ugly green and magenta stripes for the duration of a 15 min phone call and i get nothing. the grids still look black and white, even coming back to them later. i'm seriously extroverted as well so, uhm, hmm.
posted by t r a c y at 12:22 AM on April 12, 2004

I've done this before, but after posting, I stared for five minutes before going to sleep. Some 40 hours later, the colors are already quite weak, but the green is definitely still in there.

Although the McCollough effect is visually nothing spectacular (so if you didn't see it, you didn't miss the fireworks; on the other hand, monkeys have it too), it has several interesting properties. It does not decay when there's no sensory input. This has led people to speculate that the effect is related to some kind of self-calibration feedback loop in the visual system, which would automatically learn statistics of the visual world and correct the pure data from eyes accordingly, and not a simple case of neurons becoming fatigued after firing for too long, which is the reason for regular afterimages.

However, color and orientation processing are in some ways quite independent. Orientation perception occurs already at the first levels of the visual cortex, which is arranged like a stack of pancakes, one layer on top of another in the back of your head. Color perception is thought to happen a little deeper (which is exactly why we don't know it as well). It is not clear what the purpose of such a feedback loop, combining color and orientation, would be. The effect does not transfer between eyes, so it is related to quite low level processing anyway, where the images of the two eyes have not yet been combined.
posted by ikalliom at 6:11 AM on April 12, 2004

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