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Sunday, September 22, 2013

The Spinning Silhouette Optical Illusion

I never get bored with this illusion. With sheer mental power you can make her rotation shift direction. It takes some practice to do it!



Brit Brogaard said...

I noticed that the shift occurs more quickly if you focus on the upper body part rather than her legs.

Noah said...

This version shows "how" to see both directions.

Brit Brogaard said...

Thanks! That's great.

Noah said...

It's one of my favorites too. Like a super sophisticated take on the classic duck-rabbit.

Alan said...

I agree--this is indeed one of the best illusions ever. Thanks for the post Brit--though I have seen this before, this gave me a chance to think more about it.

Comment: The gif link with the color strands is terrific for enabling one to focus on one side as opposed to the other in order to make the change. I'd also note that that gif moves more slowly than Brit's version (at least on my device), which might affect switch-ability.

Comment 2: On Brit's more rapid version my strategy is to reverse motion by looking down at her shadow and focusing on her foot. That seems to enable me best to reverse the motion at will.

Comment 3: I wonder how such an illusion might be used in empirical free will studies to examine the mechanisms of how we "choose" to make the switch.

Brit Brogaard said...

Hi Alan,

Re: Comment 2: Yes, that works for me, too.

Re: Comment 3: That would, indeed, be interesting. Presumably some fMRI paradigm would need to be used. Or do you have some other experimental method in mind?

Lindsey H. said...

Still can't figure this one out. I can't tell if it's the starting point of the rotation that changes or the direction of the rotation. I love these things and I consider myself a smart person, but for the most part, I'm terrible at them!

Alan said...

Brit--I don't because unlike you I'm clueless about how to conduct such an empirical study except by spitballing.

Ok. Pose the illusion. Establish that one direction is recognized by a subject by data input and at the same time require that the subject TRY to reverse the direction. Suggest to subjects different strategies for reversal (head focus, feet focus, the red/blue line focus) and then measure by MRI efficiency relative to task and relate to report of task. See if one focused task is more efficient subjectively than others as measured by objective data in relation to report by MRI data. If one MRI datum of location in the brain is more strongly correlated to subjective reports of reversal, then a spot of FW strength is more empirically established. Wow--that took my last gulp of wine to enunciate!

Brit Brogaard said...

Lindsay: Alan's suggestion might work for you. Sometimes you just have to stare at it for a while. For most people it happens only after paying attention to the figure for a couple of minutes. It's supposed to be the direction that changes but when it happens for you, it may seem like the figure stops and then starts moving in the other direction.

Brit Brogaard said...

Great suggestion, Alan! It would be fun to carry it out.

Adam said...

If you focus your eyes on the foot in the center and blink yours eyes very rapidly, you can make it apear that she is not spinning but rather staying in place and kicking one leg to the left right rather violently.

Marcel said...

Yeah, this illusion is pretty interesting.

Makes me wonder if it really is sensible to look at the principles of belief revision without looking at the principles of belief acquisition. For me it seems like an argument that they should be thought of as intertwined.

However, as some are interested in multistable perception from a neuroscientific point of view, there were some experiments done with this paradigm, for instance: