Casual Fridays: Who can see illusions?

A couple weeks ago I discussed the Troxler Effect in my column on SEEDMAGAZINE.COM. Some people said they couldn't see the illusion, so I thought it might be interesting to play around with the effect and see if people can see it under different circumstances.

For this week's Casual Fridays study you'll see a variety of different illusions, some of which will be easier to see than others. Give it your best shot at experiencing the illusion -- we'll see if we notice any patterns next week!

Click here to participate

As usual, the study is brief, with about 10 questions. However, because each illusion takes a little time, it might take as long as ten minutes to complete. Also, the study includes a vimeo video. If you can't see these at work, you might want to wait until you get home to respond. You have until Thursday, October 1 to complete your response. There is no limit on the number of respondents. Don't forget to come back next week for the results!

(Just a reminder: All Casual Fridays studies are non-scientific. This doesn't mean we can't use scientific principles to assess what's going on, but we can't make general claims based on the results)

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You should have had a "is the circle disappearing faster?" question; it would have been interesting to see if the different shades of blue/green had different time effects...

The Troxler illusions were strong and rapid for me. It did not take a full 15 seconds. The waterfall illusion did not work, but I have experienced it in the past on more than one occasion. Once after looking at a real waterfall I looked at the cliff face beside it and there was a strong impression of upward movement.

Does "have you ever seen a UFO?" mean "Do you believe you have seen an alien spacecraft?" or "Have you ever seen something flying that you could not identify?" There is a huge difference. I very much doubt whether I have ever seen an alien spacecraft, but I have certainly seen a UFO in the second sense, so I answered yes.

It would have been a good idea to put a note in each of the ring ones saying "This isn't the one you just did." At first I assumed I'd hit the "previous" button instead of the "next" button and just re-entered my answer without redoing the test.

I interpreted the UFO question differently than Nigel (#3 comment).

I also wasn't sure what the magician question meant by "fooled" -- Just that I don't know exactly how the trick was done? (Most of the time for professional magicians)?

"Fooled" in the sense that I didn't see the end of the trick coming? (Rare, given that most tricks have a predictable ending.)

Or, fooled into thinking that the magician actually did what the trick purports to do -- levitation, telepathy, etc? (Never.)

By Marc Fleury (not verified) on 26 Sep 2009 #permalink

Another, more difficult study proposal: figure out what's going on with people like my girlfriend, who has an immediate headache/nausea reaction to a glimpse of just about any optical illusion.

By Pierce R. Butler (not verified) on 27 Sep 2009 #permalink

I couldn't get the effect to work completely after the first post, and the same with the first sample on the survey... both seemed to only have patches blank out and never the whole thing. The other editions worked fine, but I definitely started to get a headache by the last green circle on the survey.

I saw it like you did, I guess, Joel, but I started to feel sick by the end. For me, most fast animation or flashing light (such as a fan between me and lighting or driving on a tree-covered road in the sun) produces much the same effect, nausea and eventually migraine. I wonder if the illusion of patches (or nearly the whole thing) coming and going was like it flashing to me.

I couldn't see the balloon one at all.

The blue rings tended to fade away entirely; the green ones took longer to fade, then only went to a shade of gray but never quite disappeared.

Waterfall/balloon did nothing.

The magic and ufo questions are offputting in the ways other commenters have mentioned. If a saucer landed in front of me in Lincoln Park and Klaatu and Gort got out I'd have to be impressed -- but I'd be much more impressed by a blue Police Box.

By ChicagoMolly (not verified) on 28 Sep 2009 #permalink