Comments on Ero Carrera's blog: Right, Left, Right, Right, Left... and the Dancing...

Wanna know how to see it spin both ways? Just look...

2008-01-24T19:40:00.000+01:00

Wanna know how to see it spin both ways? Just look at it from 2 different angles. Either tilt the monitor or move your head sideways.

My friend and I were looking at it and both of us always seem to see the exact opposite and then suddenly it occured to us to just turn the monitor towards the other guy, We discovered at that instant our perception of how the girl moved changed. It seems to be a trick with the angles.

But It still could have something to do with which half of the brain gets to process it first. Or it could be due to the differential delay in the propagation of the optical impulse to wherever it gets processed. Dont know what it is called. Hey we are just amateurs.

- Hemchand
http://chad.skillda.com
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Everybody wants to live forever, but nobody wants to be old.

Further thought on my last comment.

This ex...

2007-12-22T18:21:00.000+01:00

Further thought on my last comment.

This experiment says something about the hard-wired algorithm in our brains that takes a 2D image from our optical nerves and converts it to a 3D model with which our conscious mind can work. The first observation is that it fills in missing details without us being aware of that (as is evident by us not perceiving the dancer as being of ambiguous orientation and rotation).

The second is that when additional details appear that conflict with the current model, it can instantly change the output model. This doesn't seem to happen very often, which is why the dancer is so surprising to us.

This might be similar to the neural phenomena that Escher always played with. He didn't use animation, though.

Commenting on an old post, but the previous commen...

2007-12-22T18:11:00.000+01:00

Commenting on an old post, but the previous comment about the shadow is relevant. The shadow of one of the feet is *not* moving ambiguously, as the rest of the image is. This is because the shadow implies a specific orientation for the surface on which she is standing, and that defines one perspective in which she is rotating counter-clockwise.

Interestly, most people see her rotating clockwise at first. Then when you lower your gaze (away from the anatomical distractions...) and look at the shadow, it instantly reverses to counter-clockwise. It's neat how the brain automatically flips its perception when given an additional piece of information.

Another trick to reverse the direction of rotation...

2007-11-30T04:26:00.000+01:00

Another trick to reverse the direction of rotation is by focusing on the shadow of the image.

Looking from the corner of the eye works great for...

2007-11-25T23:32:00.000+01:00

Looking from the corner of the eye works great for me too. I can reverse the direction of rotation with little effort.

Hey Ero,

Yeah, your technique seems to work...

2007-11-25T22:14:00.000+01:00

Hey Ero,

Yeah, your technique seems to work for me too. Seems like the high tech finger technique disambiguates the situation sufficiently for the brain - nice!

The original animation is most definitely amusing... Seems like 9 out of 10 times, I start off seeing it "rotate" clockwise. It seems near impossible to "change direction" while still looking at it when it's "rotating" clockwise like this.

But on the other hand, on the rare occasions that I do start off seeing it "rotate" anti-clockwise, somewhere along the line it seems to "change direction" (usually under a couple of minutes into staring at it).

So perhaps there is an ongoing neural bias component that is continuously present in addition to any initial bias. I've also noticed that looking at the animation from the corner of my eyes (doesn't matter which eye) makes it easier to willfully "change direction".

Amusing indeed :-)

Cheers
Nishad