Comments on: Headless skeptic

By: De grote verdwijntrucbijAstroblogs

De grote verdwijntrucbijAstroblogs — Mon, 06 Jul 2009 18:37:46 +0000

[...] pagina en een rondje links, maar Richard Wiseman heeft er een originele variant op gevonden. Bron: Bad Astronomy + [...]

By: TuckerK

TuckerK — Wed, 01 Jul 2009 02:34:43 +0000

Didn’t work for me at all. Hrmm.

By: William Hyde

William Hyde — Tue, 30 Jun 2009 21:56:16 +0000

DaveS,

When I was an amateur astronomer we used a similar technique called “averted vision”. The explanation given was that the rods and cones off centre in the eye were more sensitive than those that typically receive more light.

William Hyde

By: DaveS

DaveS — Tue, 30 Jun 2009 20:31:29 +0000

I’m pretty amazed at all the wonder and skepticism on this thing. I learned about the blind spot in elementary school. I mean, you can do the same thing with two fingers, making one fingernail disappear, almost anywhere. Like the demonstration in the video, if you vanish a fingernail, then move that finger upward until the nail emerges from the top of the dead zone, your whole finger appears, not a finger with a hole. It’s fun to play with, and has been since grammar school.

There’s another thing I’ve always noticed. If I’m looking at a star or planet, I can actually see it much better if I look JUST off to the side of it. I wonder if it has something to do with my blind spot. (No, I don’t have cataracts.)

By: Don’t lose your head. « Communion Of Dreams

Don’t lose your head. « Communion Of Dreams — Tue, 30 Jun 2009 20:31:05 +0000

[...] June 30, 2009, 3:30 pm Filed under: Bad Astronomy, Humor, Phil Plait, Science, YouTube Via Phil Plait, a delightful [...]

By: Ryan

Ryan — Tue, 30 Jun 2009 18:38:07 +0000

Why doesn’t it work for me?
Could it that I am
I am Left handed and Right eye dominant?

Worked for me and I’m right hand / left eye dominant. If people don’t have a way to reverse this video and don’t have vision in their left eye why not just do exactly the same thing with their right eye but to a point off the left side of their monitor? There isn’t anything magical about looking at the ‘x’ in the video it is just that the guy’s head has to be in your blind spot.

By: Zucchi

Zucchi — Tue, 30 Jun 2009 12:27:04 +0000

Andy C. — if you download the video, maybe there’s a way to reverse the image.

By: Zucchi

Zucchi — Tue, 30 Jun 2009 12:25:30 +0000

Great illusion. I’ve got good peripheral vision, so I could really see his body with no head.

Evil twin: good. Evil twin with a British accent: even better.

By: Mike

Mike — Tue, 30 Jun 2009 07:32:33 +0000

You could turn your monitor upside down, Andy C.

By: Andy C

Andy C — Tue, 30 Jun 2009 07:05:32 +0000

It would be good if Richard could do a version with the right eye open instead of the left, as I have retina damage in my left-eye, so no good for me!

By: Algae

Algae — Tue, 30 Jun 2009 06:54:41 +0000

I have a congenital eye disorder that effectively blinds my right eye. Normally most optical trickss (other than 3D) work for me (spinning disks, grey spaces on a grid). I wanted so bad to see his head disappear but it seems like a stereo vision trick to me. I’m always suspicious when they ask me to cover one eye, especially my blind one.

By: Jeremy

Jeremy — Tue, 30 Jun 2009 05:41:58 +0000

@Brian D

Yeah, my curiosity is what variables would impact the presence/absence of that white spot. Motion’s clearly an issue here, as you note, and speed could prove an interesting variable.

By: ing

ing — Tue, 30 Jun 2009 05:12:19 +0000

For those who are having trouble, the blind spot is approximately 15 degrees from the focal area; that’s a ratio of about 4:1. In other words, measure the distance between the cross and Mr Wiseman’s head on your monitor and then multiply it by 4… that is how far away your eye should be for the illusion to work.

By: sylva333

sylva333 — Tue, 30 Jun 2009 03:40:31 +0000

I also had a band down the middle that went away as well, I could really tell when he clasped his hands together. I love optical illusions!

By: Ken B

Ken B — Tue, 30 Jun 2009 03:34:30 +0000

I wonder what would happen if you moved a vertical bar through the image side-to-side, rather than a horizontal one up and down? Would your brain fill in the gap with the bar, or continue with the background?

By: Stephen

Stephen — Tue, 30 Jun 2009 02:45:21 +0000

The buttons on his shirt also disappeared for me – everything in a band down the middle of his body went.

By: Troy

Troy — Tue, 30 Jun 2009 02:44:58 +0000

That’s pretty cool. As others have alluded to the blind spot is the creationist’s worst night mare (sort of the way some think the banana is the evolutionist’s worst nightmare) In a remarkable instance of parallel evolution the higher mollusk such as squid and octopii have evolved eyeballs but in their case there is no blind spot. Whereas mammalian eyes evolved from brain cells which needed to turn inside out, mollusk eyes evolved from skin cells, no inversion necessary.

By: J. D. Mack

J. D. Mack — Tue, 30 Jun 2009 02:33:41 +0000

If this video had been created by anyone else, I would have expected some bloody man to jump up accompanied by a loud noise.

J. D.

By: «bønez_brigade»

«bønez_brigade» — Tue, 30 Jun 2009 02:32:33 +0000

FWIW, the book Mind Hacks covers this blind spot effect [Hack #16, p. 46-49] and many other interesting visual (and non-visual) interactions.

By: Michelle

Michelle — Tue, 30 Jun 2009 02:25:29 +0000

Amazing. I think this is by far the best demonstration I ever saw of the blind spot.

You know, it took me a while to get it right. When he starts moving that black bar I sorta tend to go and focus on the moving thing.

By: Levi in NY

Levi in NY — Tue, 30 Jun 2009 01:52:02 +0000

Nifty! I just sent this to everyone on my buddy list.

I love Richard Wiseman. If you don’t have any Wiseman books on your bookshelf, you’re really missing out.

By: JediBear

JediBear — Tue, 30 Jun 2009 01:41:18 +0000

I couldn’t really get the effect. By the time I couldn’t see his head, I couldn’t really make out anything over there, and my face was plastered to my 15″ flatscreen. Uncorrected peripheral vision probably didn’t help the lack of focus any.

By: Wayne

Wayne — Tue, 30 Jun 2009 01:22:27 +0000

My uncle’s eyes were damaged in a high-G car crash, and originally he saw black donuts in his vision. Eventually, his eyes started filling in the blind areas, but failed to notice pictures on the walls and he said reading was like pushing a washer across the page since the letters kept winking in and out. It’s been many years now, and he’s gotten so accustomed to the blind areas that reading etc. no longer takes any special conscious effort. The brain truly is amazing.

By: TwoYaks

TwoYaks — Tue, 30 Jun 2009 00:51:58 +0000

For the folks who think it doesn’t work for them, keep trying. Unless you’re a squid, everyone has this blindspot. It’s just a matter of finding it, which (admittedly) can take some time…

By: Eric

Eric — Tue, 30 Jun 2009 00:09:58 +0000

22″ screen for me, fullscreen shows illusion appx 3 ft away.

I don’t think eye or hand dominance has anything to do with where the optic nerve attaches. I am right handed but left eye dominant, my wife is mostly ambidextrous while favoring left hand and right eye dominant and also sees the illusion.

I do wonder if there is some vertical differentiation from person to person in where the blind spot is located. When I find the blind spot, I still see his jaw moving while the upper head is completely gone. If I focus just below the X his whole head disappears.