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By on December 27, 2010, with 99 Comments

Peter Tse from Dartmouth College (USA) has re-invented the classic afterimage optical illusion. If you haven’t encountered afterimage illusions before, I strongly recommend visiting #Afterimages category before reading through rest of this entry. So why is this illusion different? By using it, you can reveal if your brain predominantly sees horizontal or vertical lines! To begin, you’ll need to fixate the colored image (one on your left) by looking at the fixation spot for about 60 seconds. Now shift your eyes to the fixation spot surrounded by rectangular outlines. Which afterimage did you see first? You can manually shift which afterimage you experience by attending to one rectangle and then the other. If you attend to the vertical outline rectangle you will see the afterimage corresponding to it, and if you attend to the horizontal outline rectangle you will see the different afterimage corresponding to it. Now wasn’t this great?!

  • Louie

    I saw the vertical one first. The stripes look pink and white. The horizontal one just looked like a dark shade of gray to my eyes. I couldn’t see the stripes horizontally.

  • http://www.facebook.com/people/Lasse-Kiilerich/742482478 Lasse Kiilerich

    Horizontal…but is’nt that the color that stands out the most?

  • qwertyuiop

    i saw horizontal first

  • Shriya

    I don’t actually get this…it’s confusing:(

  • Mary

    Very interesting! It was HARD to concentrate on the dot for 60 secs, it kept trying to change the colours I was looking at. Then, when I did transfer to the other blank rectangels, they were slightly diagonal, not in the same horizontal and vertical directions. I also found that when I blinked, the other orientation came into view. But I started with the horizontal only.

    • http://www.facebook.com/people/Peter-Gorham/1046321338 Peter Gorham

      Same as my experience. With each blink, the orientation changed.

    • Kelly

      Same here too. But I saw the vertical ones first. It was only after 10 seconds or so that I could see both vertical and horizontal images at the same time!

  • Daniel

    i saw horizantal first… but couldn’t the lightness of the blue and yellow and the darkness of the green and black effect this?

  • http://www.facebook.com/people/Mitchell-Taco-Nash/540775439 Mitchell Taco Nash

    Wow! That IS cool. I liked this illusion. Totally worth sitting still for 60 seconds.

  • ZL123

    I can’t do it *cries*

  • ohmygosh

    I see the vertical lines first

  • http://www.zomgmo.com Sharpie

    horizontal first

  • layneee

    wow that was cool while i was reading i could see the horizontal lines. Super cool illusion :)

  • breandan

    Um…both. When I looked at the blank side I saw plaid. Guess I’m just a bit strange. LOL

    • liz

      I saw a checkerboard.

    • Berenise

      me too!was red and white for me

  • Cybe R. Wizard

    I think you instead get the darkest (vertical) lines first in the after image. If the image is rotated 90 degrees don’t the same lines (the darker) appear first?

    • Tested the color theory

      I actually turned my laptop sideways to see if the color rather than the direction of the lines was what made me see the lines vertical or horizontal. My brain picked up he black lines (which turned to pink/ white) both times! Vertical to start, then horizontal (when the sideways laptop rendered them so). I’m not sure what this expirement actually proves, but it is interesting that everyone sees it differently!

  • bg4life


  • http://www.facebook.com/people/Mike-Brown/1155429974 Mike Brown

    All I can see is the vertical one, I can’t make the horizontal box appear :(

  • http://www.headprimer.com chewhorse

    That’s all fine and good (horizonal/vertical illusion) but what does it mean (orientation). Just knowing which your brain prefers isn’t enough, there has to be a reason (no matter how mundane) therefore, a hint as to what it all means scientifically or otherwise should be explained otherwise it’s really useless as far as curiousity is concerned.

    • Renee

      Loved it (saw vertical first), but I agree…what does this mean? Maybe left/right side of brain?

  • http://www.facebook.com/people/Anadi-Kulkarni/642890304 Anadi Kulkarni

    i got horizontal! pretty cool

  • Sean

    Cool! I saw the horizontal lines

  • Honey

    I LOVE THIS ONE, first i saw horizontal, but then i could see vertical tooo, and i can switch between them… this is AWESOME!!!!!!!!!!!!!!!§

  • Darren

    I See both horizontal and vertical. weird?

  • Farewell

    It started out horizontal then when I blinked it changed and I could keep changing it :) pretty trippy x3

  • wiktor

    for me it was verticle

  • judy

    That was very odd and now I am seeing stripes everywhere I look.

  • ironarjen

    Nice but isn’t this a bit of a fluke? There are many aspects that affect this such that it is no longer an honest optical illusion. 1st: Human vision is slightly more horizontal than vertical (both eyes cover a circle). Second:there are colours that might affect your preference. Third, the horizontal lines are on top of the vertical lines. 1 and 3 will render a preference to horizontal whereas it is known we actually do prefer vertical since from an evolutionary point of view, vertical objects are of greater importance. I think to get a more honest idea you should also check this with a 90 degrees turned picture.

    • http://beavers.com Orack Bobama

      On what do you base that the horizontal are on top of the vertical. It is just as easy to say that the vertical lines are on top of the horizontal.

    • http://dasapierce.com dasa

      ironarjen – good point – I turned the illusion sideways – I get dark blue vertically. I got the same dark blue horizontally as presented. The color is dominant over any vertical or horizontal bias.

  • hazar

    i see vertical ones.

  • http://www.foxnews.com Vincent Van Goh

    Totally worked – vertical

  • http://BowlingTracker.com James Smith

    Cool. At first I saw the vertical bars, then was able to “shift” to the horizontal bars and then back and forth before the effect wore off. At one point I was able to see both in the after image.

  • catzrules

    i saw the horizontal first. anyone else?

  • Mitch

    Vertical first then horizontal.

    Interestingly, before even getting to the after-image, I began to see the pattern as columns of three dimensional ridges. Initially the “shadowed” side was on the left, but with some coaxing. I could shift the ridge tops over so the shadow was on the right (as if the light source switched).

    With a little more effort, I could switch to horizontal rows of ridges.

    My guess is that which ever way you view the ridges is the way you will view the after-image. That was my experience. And,if I alternated rapidly between vertical and horizontal ridges on the right, I ended up with a checker board after-image.

    This is an excellent, multilayer-ed illusion.

  • http://moillusions.com Lil’ Smily

    i dont get this…

  • fossda

    i saw the vertical ones first. 1st comment!

  • a person

    thats so cool!!!!!!!!
    I’m horizontal

  • Florin

    I see the vertical ones and after a few second the orizontal ones and so forth , that’s strange:))

  • patch

    Horizontal. :)

  • glp

    not sure what is supposed to happen here. I see the checkered aftermath illusion, not necissarily one or the other. I see both just as the colored image is. I can then force myself to see one, but i see both if i stare at the dots, moving my eyes to a direction cause only one image to appear. Poor illusion. Im pretty disapointed in the last few weeks illusions.

  • http://beavers.com Orack Bobama

    kind of wierd. Initially it was horizontal, then one blink, and it turned into vertical stripes.

  • Sitroentje


  • Voigt_Meister

    Excellennt after image. I saw the hoizontal lines first. I can shift between vertical and horizontal quite easily.

  • http://beeterz.com Oxyman

    horizontal outline – I saw them so what does this say for me???

  • http://www.facebook.com/people/Matias-Hosiasson/743778493 Matias Hosiasson


  • Linda Walter

    Alright, I see the horizontal lines first and the vertical followed when I concentrated on that box. But…..what does it mean??

  • Erin

    I saw vertical first!

  • William Lim ‘nkm’ Miaw

    failed on me

  • SnowBerey


  • Bill Weaver

    I think it has more to do with the colors, because when I did it the first time I saw the vertical image, then I turned my head sideways and did it again that time I saw the horizotal image.

  • A Snail

    Horizontal for me to start with, flipping between them was relatively easy.

    The flashing advert started to get annoying whilst looking for 60 seconds :)

  • Nikolai

    Mine had Squares going up diagonally. Is there something wrong with my eyes? e_e

  • asianpearlkeeper

    I saw horizontial but they are brighter colours. Did that change anything?

  • dylan

    :/ i saw both at one time

  • Felix Ruber

    Waffle ???

  • DetectiveKitty

    I say vertical lines first….

  • shino

    i can see horizontal and vertical at same time :/

    • Thhp

      same. :/

    • Ro Mc

      I originally saw horizontal, then each time I blinked it switched between vertical and horizontal again. After about 10 blinks, I saw both interlayered at a slightly skewed angle (with the top of the verticals leaning to the right) – haha maybe I stared for too long.

    • Ella Bella Farmersita


  • tinkel

    vertical first

  • robith nuriel haq

    yup, it definitely is vertical

  • FlickerFly

    I saw horizontal than vertical than both…

  • mia

    i saw horizontal first

  • mini_2

    I saw horizontal first!

  • Nyasha Maenzanise

    horizontal first

  • Darryl Huang

    at first vertical but when i blinked i saw horizontal

  • AppaloosaGirl

    I saw horizontal, then I blinked and it was vertical, and then I blinked and it was horizontal again. After I think 5 blinks it stayed horizontal.

  • barnabas

    its difficult both

  • Natalii

    I saw vertical then without blinking i saw horizontal then it kept switching

  • Penny

    Horizontal but orange and blue

  • Mina

    Horizontal and when I blink it goes to vertical, blink again to horizontal again etc… cool :P

  • BJ

    horizontal 1st then both 4 me

  • Smocking ace

    verticall firsttt

  • Crow

    At first I saw squares, then horizontal stripes, then vertical stripes

  • Jamie

    I wonder if the colors have anything to do with what you see first… I saw the horizontal first, but I wonder if I would see the vertical first if the colors were switched (if the horizontal stripes were black and green and the vertical stripes were blue and yellow).

  • Rob

    This is one of the best one’s on here! I saw vertical first but was able to shift and see either one at a time! Really concentrate and focus on the white dot for 30 seconds!

  • Anonymus

    i see vertical first!

  • AshtonC1997

    WHOOAA! At first I see horizontal and if I blink I see vertical and I blink again and see horizontal and soo on, until the image fades from my eyes! :DDD AMAZING!!!

  • Alex

    I saw… pink dots. ¿?

  • cool froggy

    Horizontal first…

    its sucha weird word now just thinking about it…


  • Shuuc

    lol i saw both at the same time :DD

  • Heather

    Vertical! but changed with each blink

  • Liz

    Well, if I blink alot I see the vertical, THEN if I blink again some more,I see horizontal, but I think the one that stood out the most was the vertical.

  • someone

    at first i only saw the horizontil, but now i can see the vertical

  • Yay

    I saw both. But they were diagonal.

  • Stephanie

    I saw horizontal first, then I saw vertical, and then they kept on switching when I blinked.

  • http://this.com well


  • http://insetologia.blogspot.com Cesar Crash

    I saw vertical first, and I thought it was obvious because the verticals are darker, than it has a higher contrast to the white background of the page.

    • emily

      really? i saw horizontal first…

  • TheRhyslightning

    I found that I can’t see the lines unless I blink rapidly and in doing so I found that If you blink hard you see the Vertical lines but if you blink not so hard you see the horizontal lines…

    Hope this helped

  • Berenise

    My comments appear with a time difference of 5 hours! Was fun to notice.
    (Still can not get used to globalization)

  • Someone

    I first saw the horizontal~

  • Stefan Brinks

    I saw the blue and yellow horizontal stripes first.

  • Derpy

    I somehow saw Diagonal lines.*

    *I guess i didn’t look long enough…

  • Mevin1

    I saw vertical first. Then I turned the image 90 degrees, still saw vertical lines, but different color. Then i turned the original image 45 degrees, I saw all the lines diagonally.