Wow im confused

me too!!!!!!!!!!

Pay attention when it's in "13" mode-- one person has cut off hair and one has cut off soles of their shoes. So the extra person comes from you not noticing that not all halves have been put together exactly in line again.

There's also some trickiness going on with the faces. In "12" mode, look at the 2nd guy from the right. If you watch his face you'll see that the neck line of his T-shirt becomes his chin in "13" mode.

Actually, if you pick almost any feature you can see that it's either missing on one guy in "13" mode (like the head-tops and shoe soles mentioned by Dan), or is "simulated" by some other feature. Pick some feature, and then follow is from each of the guys in "12" mode to see where it ends up. Then by process of elimination, the one remaining guy in "13" mode is either missing or simulating that feature. Another interesting one is that the 4th guy from the left has no eyes in "13" mode. What you think are his eyes are really just the sides of his nose.

Our minds are pretty forgiving when looking at drawings. We tend to fill in a lot of details that aren't really there. (This is also why we aren't particularly bothered that Bart Simpson only has 4 fingers and no nostrils.) This illusion takes advantage of this by stealing random details from different people to make an additional person. Even though this results in most of the people missing certain details, our minds fill in the rest.

I made an image using frames from the animation to show what Dan was talking about.

The first frame is the initial "12" phase. I used colors to match each bottom with each top. The second frame show the arrangement of tops and bottoms during the switch. The final frame shows the "13" phase. Two of the characters are missing the other "half" of their image.

Also, some of the characters end up noticibly shorter, as if giving up height to create the "thirteenth" person. This is akin to the missing features that Lawrence noticed.

that was so easy there is 13 people in both pics

I have figuredit out nothing finifhes one guy and soit makes a new one wach closely

An wonderful illusion. All the twelve guys contributes some part of his body to make up the thirteenth guy. In the thirteen picture each guy has lost something from his body and is shorter as a result.

in the 12 mode, people are "created" with a part of the upper half of the image AND a part of the lower half. in the 13 mode, 2 people are created by using only one half: the left guy has no "upper-half"-ingredient, and the 6th guy (from the left) has no "lower-half"-ingredient..

tha one that made this must be a ADHD person... good job!!

It takes a little work to figure it out, but the "extra" man is created by having 1 man NOT have a new top and 1 man NOT have a new bottom when the shift is made.

In other words, if the shift was a direct match up, each bottom would have a corresponding top. So 12 bottoms would match up with 12 tops, creating 12 men. But when you don't match up a top with a bottom, you have 11 complete men and 2 "half" men. And in this case, the missing halves are so tiny, our eyes don't see anything as missing in either of these 2 "half" men. Therefore, it effectively creates the illusion of 2 "whole" men rather than the true "half" men. So when you add up the original 11 men with these 2 illusionary whole men, you get 13 men total.

Looking at the 13th mode, the guy in row 1/bottom has no top, and the guy in row 2/top has no bottom. So rather than matching these two "men" up to make 1 man, they are split which creates 2 men.

What I did was color code each man while they were in the 12 man mode, numbered them, and then did the split which is what showed the "extra man" and where he came from. To reproduce what I did, take the 12 mode picture and color each man a unique color. Then split the picture, reproducing the 13th mode picture which now mixes the colors. You can now see which top goes with which bottom. If you were to chart it out, it would look like this (using the 13 man mode, counting from left to right, each row being counted from bottom to top):

Man 1 = NO top + 1 bottom
Man 2 = 7 top + 2 bottom
Man 3 = 8 top + 3 bottom
Man 4 = 9 top + 4 bottom
Man 5 = 10 top + 5 bottom
Man 6 = 11 top + NO bottom
Man 7 = 12 top + 7 bottom
Man 8 = 13 top + 8 bottom
Man 9 = 1 top + 9 bottom
Man 10 = 2 top + 10 bottom
Man 11 = 3 top + 11 bottom
Man 12 = 4 top + 12 bottom
Man 13 = 5 top + 13 bottom

It's really very simple once you see it, but the illusion is very good without close examination.

EXCELLENT I LOVE IT THIS IS WHAT ILLUSION MAN!

It is really confusing. :-p

that weird is, hai?

It seems that this illusion was around way before PC's were.
Paper and cissors did the trick. It was even more astonishing then! You could shift the three pieces of the "puzzle" yourselve to see there was no "trick"
Still amazing!

Thank you for the fun this provided.

i agree with walrus..im lost and i cant pay atenton that long to see complexitys explanation
=^.^=

One group of men has one less than the other.

the torso from the guy all the way in the right in "12" mod makes the new guy, and gets legs. the right slide dosent move all ath way over, it only moves to 1 guy from th right. this is why the torso dosent end up on anyones legs

there is 12 and 13 cant ya teel

To Brian D
You can't count if you think that there are 13 in both pictures. You sould go back to pre-school!!!

i still got 13
=^.^=

Watch on the 12 mode watch the guy on the very right side on top and follow him untill he stops and you will see that there wasn't any body there in the 12 mode

i finally understand it!!! it was so confusing at first but when the change is made two people do not change

Laurence said: Another interesting one is that the 4th guy from the left has no eye in the "13" mode.
WRONG.
Look closely-- You see 2 eyes above the nose. They ARE the eyes. Not the nose.

Great

all of you that think its wierd guess what your all are wierd cuz there are 13 people ` `
-

my head is hurting

IT MOVES!!!! wow

this was doin my head in! til i found this website http://www.moillusions.com/2006/05/count-people.html
its the same sorta thing n explains it really well :)

1st 13 2nd 12 cuz people lose body parts when it animates...ew
=^^=

ok...wat!! this doesn't make sense would anyone like to try to explain this to me??

Look at the second row there are three people (13) and then there are two people (12)Because that is the way it is drawn. Can't you see it!

one time there is 12, the another...13...im SO confused!!!!lol

this is a easy one. theres a extra person in"12" mode that makes you think another person is added. when one thing changes, to "13" mode, its juts that nobodys cut off.

As has been mentioned, one man's hair is missing, and another man's soles are missing. You may wonder what harm this could do. But the results are significant. When the man on the left loses his hair, where do you think it goes? It goes to another man who already had hair, but a slightly more abundant tuft of it. Now that we've given him his new hairdo, what do we do with his old one? Give it to someone else with even MORE hair. You can think of it as starting with a penny, and convincing a friend that he might as well trade you two pennies for your one penny, since the difference is negligible. Then trade those two pennies to another friend for a nickel. By the end of the day you could have made a full dollar, just as by the end of the animation you can make up an entire man. The tuft of hair that we started with gets larger and larger until it has become the man with the missing soles. If you don't believe me, you can watch the whole cycle yourself: Look at the smallest tuft of hair on the man on the left. Every time the animation moves, see where you land, and switch your attention from either the top to the bottom, or the bottom to top, whichever is appropriate at the moment, and continue this process until you have no where to go. At this point, you have either reached the man with the missing soles, or the man with the missing hair. If you are willing to wait 24 shifts, you will see the entire cycle. Notice how each time the "half-way line" creeps either up or down ever so slightly after each shift. It goes to show you how little, negligible changes can add up to a tremendous result! It's the idea behind calculus!

there are 13 and a turd

the 12 mode is the origanal,full version cos the second one has 2 incomplete

so cool

I think that the following 3 images allow to understand easily what is happening:
http://www.lucbollen.be/12to13/12to13-image1.gif
http://www.lucbollen.be/12to13/12to13-image2.gif
http://www.lucbollen.be/12to13/12to13-image3.gif

Note : I elaborated from the image provided by Jokermage, and the textual explanation is provided above by Complexity and Daniel Walsh

You can count that before and after the move, there are 12 "parts of body" above and below the line. But after the move, 2 such parts are left alone...

So many theories, all wrong. Look at the "12" men and watch the guy in the back row furthest to the right. When he slides into the "13" men picture he has his foot cut off and becomes the "13":th man because he is the only person not sliding into another part of body. Simple as that. You can easily verify this by watching the "13" men picture and see that he has no friggin feet!

I finally got it! if you print this out and cut it through horizontily exactly where the shift is then cut the five top images on the left vertical to separate them from the 7 images on the top right(make sure you include the little pieces of hair) (use the pic with 12 people) put the right side back where it was. now take the left side and put it on the right side off the one that is there. now slide both to the left until it matches up as 13 people. you will notice that you took the hair of the first person on the right when you moved things but when you slide them over you don't slide anything back on top of him. you take 12 parts off the top to move them and when you replace you put nothing back on top of the first person so figure it out from there.

if you print this with 12 men, you can, I did it. Cut through horizontily on the exact line where it shifts then cut vertically through the top piece where it splits. ( the first guy on the left on the bottom should lose the very top of his hair) there will be 4 body parts in the part you cut out off the left side and 7 on the part you cut from the right (that is a total of 12 parts you cut off of the bottom so when they get moved they should go back on 12 parts of the bottom) Take the right side that you cut with the 7 parts on it and put in back where it came from, now take the right side piece with 5 parts on it and set it to the right of the other, slide them to the left until they are in the position for 13 people, you will notice that the top 12 pieces that came off the top only slide 11 spaces to the left and does not replace the part you removed from the 1st person on the bottom left . So, you know there is an extra piece on the top (you now have to count the missing hair on the first person on the bottom left as a piece of the top which now gives you 13 pieces on the top above the shift line. The extra person in the top of the second row becomes the extra person derived from the fact that you slid her over into a blank spot. If you slide the right top piece you cut out with 7 parts on it over so that the 1st on the left covers the 1st part you removed from the left (the top of the bottom left guys head) and you put the part you remove from the top left and put the position it takes up in the animation, you will see that a peson shows up between the two sides. this is the 13 person. when you slide everthing 11 spaces she is in the top second row but if you moved over 12 spaces which how many parts you removed from the top things will start to clear up. NOW for what is really happening! take the part that is moving from right to left. (the part with 7 parts on it) take it and put the 1st part over the guy who lost his hair on the bottom left , now turn this piece counterclockwise so the second part is on top of the second part of the bottom. that is two people, next shift it so the piece of hair, 3rd part over is with the top person in the 1st row(1st 3 parts or the top put with the 1st 3 parts of the bottom) here is the place where you can see what happens, take the top piece your working with (the one with 7 parts on it ) you already saw where the parts should on the 3 if you moved over 12 instead of 11 spaces. now line up the 4th part of the top piece with the 4 part of the bottom and then the fifth part of the bottom with the fifth part of the top and wahlaw! the bottom man in the second row and the man directly above are the same guy! The extra women in the 2cd row top should actually be where the man in the second row middle is. If you can follow my directions, You will see what happens. all of the rest of the explanations with #of people and colored people and 60" people and whatever are whooeee.

The sixth guy from the left during the "13" mode is there, but when it switches to "12" mode, he's gone. When they're seperating the picture, it leaves his shoes behind, and another person takes his place, but when it's switching back over, he leaves nothing behind. So they're not really seperating him, it looks like they're just adding another person because they seperated his shoes and left part of them behind.