vortex (mis-)explanation

[ctw]

I absolutely agree with Randi that the effect shown in the original photos is an optical illusion but his explanation seems clearly wrong. In the original photos, the person on the left looks smaller. In Randi's reproduction, he looks taller on the left. I think the angle of the board in the photo is probably because the ground is sloping - but the slope isn't obvious because where the ground meets the vegetation at the back it is horizontal, and the fence post slopes the other way. In fact the person's feet on the left are obviously lower. Hence correcting the photos for the slope of the board (in the rotated photos Randi presents) does remove the illusion - and indeed, this would not remove the illusion if the actual figures were different sizes due to different depths as Randi is suggesting.

CTW

(first post of a long-time lurker)

 

[Raphael]

Randi just did it right. The Vortex guys are sloppy.

 

[ctw]

Randi just did it right. The Vortex guys are sloppy.

Well, Randi used an alternative (and arguably a better or more subtle) method to create the same general effect. However it was not at all 'right' as an explanation of the original photos. Seems a bit of a case of being too clever, and hence missing the obvious explanation (ironic for Randi to do such a thing!)

CTW

 

[Bruno Putzeys]

If you know how to overlap two pictures visually (the cross-eyed view), you'll notice that the vortex pix register perfectly except the white board. The white board moved between shots.

I must say that I failed to see an illusion at all in the vortex pics.

 

[ctw]

Well, I have to say I am a bit disappointed. I emailed Randi with essentially the same comment as my OP here last week. He makes two further mentions of the vortex in this week's commentary, but neither address what I think is the central point: he claimed to provide an explanation of the original pictures, but demonstrated it with a method that produced *exactly the opposite result* to that shown in the pictures (i.e. person on left looking larger vs. smaller).

Anyone silly enough to think the original pictures are anything but an optical illusion (and as others have pointed out, a very weak one, the heights really don't seem much different) would be quite justified in asking "How can showing the opposite effect be proof of a correct explanation?". I work on scientific models: it isn't usually seen as a good result if the model I build produces the opposite result to the experimental data.

Randi (in the first commentary) makes much of the small angle of the board indicating its orientation in depth, and that the person on the right is slightly more front-on than the person on the left, and that turning the photos makes the illusion go away. Each of these points would be incorrect if his demonstration was the right explanation. Am I really being overly picky in expecting that if you are going to give an account of how some claimed paranormal illusion was created, you should be expected to give a coherent account that creates the same illusion, not a mixed up account that creates the opposite illusion?

CTW

P.S. Also disappointed noone said 'hello' on my first post...

 

[brettDbass]

Well hello, ctw.


I just thought Randi had done the illusion left-right whereas the original had been done right-left.
Mind you, I really didn't pay much attention to that bit; as you say it was obviously a poorly executed optical illusion. At least when Randi did it it was done well.

 

[ctw]

Well hello, ctw.

Thanks.

I just thought Randi had done the illusion left-right whereas the original had been done right-left.

A simple left-right flip would require 1. the board to slope the other way in the original, 2. the person on the left to be more face-on in the original 3. the illusion not to be changed by rotation of the photo, because the two people would actually be different sizes in the picture plane.

CTW

 

[Hastur]

CTW, Randi DID get the same result as the vortex photographs. It's not the EXACT SAME setup, but it IS the same setup for all purposes -- orientation and perspective makes one side seems larger/smaller than the other. The mechanism is described and demonstrated adequately; your point is just a nitpick red herring.

 

[ctw]

Let's see:

The vortex photographs present a (rather pathetic) illusion of change in height using the mechanism of people being in different positions on a slope.

Randi presents a (rather good) illusion of change in height using the mechanism of people being at different positions in depth.

Randi says these two things are the same mechanism, providing a chain of
reasoning about details in the photos to support his argument (n.b. he didn't
say something like "In general, producing this kind of effect is trivial, look,
here's another way to do it" - HE claimed it was the SAME setup).

I point out the two things are not the same, and that the chain of reasoning is fatally flawed because it produces the result A>B, when the effect to be explained was A<B.

You say this is a 'nitpick red herring'.

I wouldn't want to argue about something important with someone using this
standard of logic, but as it is a pretty trivial issue I think at this point I will just let it go...

CTW