I haven’t posted a new Quirkology video for a long time because they are a tad tricky to create.  However, about a month ago I came across a nice use of the blind spot by bored lawyers. Apparently during a tedious court case they occasionally pass the time by covering one eye, looking at the judge with the other eye, and seeing if they can make the head of the witness disappear!

This got me thinking, and after a bit of experimentation I came up with the following video….

Hope that you like it. Getting the black bar bit to work was problematic, but we got there in the end (and my thanks to everyone involved in the creation, filming, editing and testing process, including Caroline, Emma, Sarah, Peter, William and Ringo).

When researching the idea I came across several nice blind spot demos, but my favourite allows you to map the actual size and shape of your blind spot. Have fun playing with it here.

15 comments

  1. One of the best illusion videos I have ever seen. Good job!

    I experienced a secondary illusion, possibly because I have a form of severe astigmatism called keratoconus -these kind of experiments work really well on me. When you begin to lift the bar the middle of your torso disappears in exactly the spot where the bar sat to begin with. I can see the orange wall behind you while your ghostly beheaded torso floats above. wooo!

    I experience these kinds of illusions every day in a way, as my badly distorted vision, so different in each eye, struggles to assemble the correct image in my brain. I have had many bizarre experiences of “seeing what I expected to see” and then discovering with a jolt that my brain had filled in the blanks in my visual image for me and the truth was completely different.

    Two examples, I was lying in bed, a friend came in, I said “hello Mary” and she said. “I’m not Mary, I’m Louise”, and at that moment the face of Mary, which I thought I was seeing perfectly clearly, morphed into the face of Louise.

    Another time I was walking down a completely clear aisle at a grocery store.. until.. crunch, I was standing in the middle of a giant broken bottle of pickles. At the moment of the “crunch” again my vision morphed so that my experience was of the pickles, broken glass and brine suddenly appearing beneath my feet.

    They hadn’t of course, my fatigued visual system had simply drawn the picture in my consciousness that I had seen so many thousands of times before, of what was most likely – a clear aisle. The jolt from another sense letting my consciousness know that the situation was not normal triggered the “real” image to appear.

    I think because of my condition I am able to experience what is going on for all of us all the time with our vision, pretty much without our knowledge – except when cool experiments like this one can demonstrate it so clearly.

  2. I’ve never been able to get blind spot experiments to work for me before. The video worked, but I felt sure that it wouldn’t if the background wall had been less similar in colour to your head. I also felt there was a touch of suggestion going on, because the illusion became more vivid at the moment that you said it was an amazing illusion.

    The blind spot demo you linked to worked, and I’ve uploaded a screenshot at http://outerhoard.files.wordpress.com/2009/06/blindspot.png in case people are interested in comparing results.

  3. Find an object nearby you, hanging on a wall, on your desk, anywhere. Stare at it. Stare at that object intently. Keep your eyes exactly where they are. Without moving your eyes start paying attention to the things around where you’re looking. You’ll more than likely get a kind of tunnel vision where those things around where you’re looking fade or blur to a degree.

    Our eyes work by capturing movement, taking two images and comparing them. If you look very closely at someone’s eye you’ll see tiny little movements when looking straight ahead. Start paying attention to what your eyes are pointing at, you’ll find it almost constantly moves and takes a fair bit of concentration to keep them (apparently) still on a certain point.

    This illusion takes advantage of this by having a background somewhat similar in colour to Richard’s skin colour. We see his body and the pole due to them moving around almost the entire time so they’re constantly registering in our mind while his head stays somewhat still and therefore doesn’t register in our minds. The similarity in colour is the icing on the cake for the illusion through bog standard camoflage.

  4. Lovely video…I have found another really kind of weird thing to do with this clip….If you make a tunnel with your right hand and place it in front of your right eye…and if you completely focus on the cross with both eyes…then weirdly (well with me though) if you move to the screen and back slowly then the blind spot seems to be gone (as in, i keep seeing you richard) and the crosses are two on the screen?…

  5. Very precise, how you described what would happen and how it did! Will try it out in person next opportunity, and in other ways if possible. thanks!

  6. You have to view the video in full screen and position your head so that the left eye is directly in front of the “X”. Then it’s a matter of moving your head backwards or towards the screen without any lateral movement until you don’t see Richard’s head and always mantaining the “X” in focus (even a slight movement of the eye looses the effect) This demonstrates the “blind spot” – a small area on the inside of your eye where the retina connects to the optical nerve and does not have any sensitivity. It’s not an illusion created by your brain – you really can’t see the head in these conditions. All vertebrate animals have this “flaw” in their vision but some invertebrates like squids and octopus don’t have that so their eyes are “better”.

    Final note: If the bar wasn’t whole black I think it would appear black on the middle when it passes over the head.

  7. this didn’t work for me – I tried it 5 times, then tried it using Iflcorreia’s instructions, and still no effect

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