Look at this picture of a girl spinning. (Solid black figure, so should be safe for work, but for some odd reason, there are tiny nipples visible on close examination.)
You will either see it spinning clockwise or counter-clockwise, and if you concentrate, you can switch the rotation.
I see rotating counter-clockwise by default, and there are three methods I found to switch the rotation:
Concentrate on the grounded leg and unfocus your eyes. This only works for me to switch it from CC to C, not the other way.
Do the same thing concentrated on the shadow to switch the rotation to CC.
This is a method I found by myself when I hummed a song while looking at the picture. To switch it to clockwise rotation, hum a tune in your head; to switch it to counter-clockwise rotation, do simple math problems. One of the main reasons for my asking this question is that I want to see if this works for other people or if it’s just confirmation bias on my part.
I heard that the rotation you see is based on which “side” of the brain you’re using, with the creative functions being dominant producing a clockwise spin and logical functions being dominant producing a counter-clockwise spin; is this scientifically sound?
That is officially the best optical illusion ever.
I can only get it to switch direction by focusing on the ground foot. And then I can only get it to go from clockwise to counter clockwise, not back again. I have to look away from the image to get it spinning clockwise again.
These optical illusions never work on me. I can’t get the girl to switch directions and I stared at the colored grids for a good ten minutes without anything happening. I’m not sure why, I suppose it could have something to do with my lazy eye (though the second one may be my attention span, my eyes may have wandered without me noticing).
Dr. Angry works though, that’s a nice one.
As for the first one, I’d have to guess it has to do with focus, depending on which part of the model or scheme you’re focusing on, you end up registering different parts of motion more easily.
Edit: I got the one in the OP to work, I had to turn my head away from the computer to the right and look at it out of the corner of my left eye and then slowly turn towards it, the opposite didn’t seem to work for switching it back though.
Edit2: Nevermind I can get it consistantly to switch by moving my head to the side, looking at it, and concentrating on seeing it go the other direction while I can only barely see it. Left eye for Clockwise, Right Eye for widdershins.
I believe that the illusion in the OP has the girl not spinning but more like swinging.
She makes a half rotation anti clockwise and then swings back clockwise. ( Extended leg swings to point to the left of the screen then swings back to point to the right and continues). Now I think that they are just passing a sine wave through this motion and depending on where you come in depends on which way you will see her rotating.
To switch direction: look just to one side so the illusion is in your peripheral vision. You should now see the swinging I was talking about. Now just switch your attention back to the illusion for the direction you want to see based on the current swing movement.
Is there a logical place that the light source could be where, if she were spinning clockwise, her raised foot, while furthest from the viewer, could create a shadow closer to the viewer than the planted foot? It seems to me that that light source would have to be on the opposite side of her of the viewer and not too high up, hence, the light source from the clockwise image should be in the picture, and it isn’t. I wonder if that’s part of what’s supposed to seperate the left/right brain thing.
I see it clockwise most of the time despite it seeming less logical.
Then again, it’s 4:40am, and I might not be thinking this through clearly.
Are those ghosted imprint lines she leaves necesary for the illusion? If so, why?
Interesting. If you block off everything above her mid thigh, at least for me, it appears that her raised leg appears from behind her planted leg, goes left until it has rotated in front of her plant leg, and then suddenly dissapears at the same time the raised leg reappears behind the plant leg going the other direction. In other words, behind-left-front, behind-right-front, behind-left-front, etc.
I see clockwise by default, but can readily change by looking at the shadow cast by the extended foot. I love stuff like this, because it reminds me to have a healthy respect for the limitations of perception and cognition, which I find very useful in evaluating political and religous stuff
