I finally worked it out

This puzzle has bugged me for years. Take a right angled triangle and split it up like this, call it triangle1

Now rearrange the pieces like this to give triangle2

The overall triangle is still the same size 13 by 5, none of the pieces has changed, so where does the hole come from?

Not convinced? Here’s an animation.

Draw it out yourself and cut it up with scissors. It works. It is true, or so it seems. Of course it's a subtle trick. It all looks convincing to the eye and, given the accuracy of drawing on graph paper and cutting with scissors, it works on paper.

The solution? The easy way to see it is to superimpose triangle1 on top of triangle2.

Hey! there's a bit left stuck out along the hypotenuse - that bit is the trick. Here's a blowup:

In truth, triangle1 is a smidgeon smaller than a real 13 by 8 triangle, triangle2 a gnat's hair bigger. That slender difference, surprisingly, adds up to 1 and that's the size of the hole.

Just as a last observation, look at the whole (integer) numbers needed to make these shapes.

The main triangle is 13 by 5
red is 8 by 3
blue is 5 by 2
yellow and green have sides of 1, 2, 3 and 5
the hole is 1 by 1 but really zero

Er...
0,1,1,2,3,5,8,13

Where have I seen that before? Of course, now that's interesting!
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svg code for images adapted from here. See also Missing square puzzle. Grow into these trousers... >>

Wicked illusion

Do NOT try this if you suffer from epilepsy or any strobe-light induced disorientation or nausia!

If you've done acid or mushrooms it's a doddle :)

1. Go to this link http://www.neave.com/strobe/


2. Stare at the moving pattern for ½ a min


3. Look at your hands

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Via the Bad Astronomer, from Richard Wiseman on Twitter (whatever that is). Grow into these trousers... >>

A rather amazing optical illusion

Via Amazing Illusions.

Who do you see? Well it's old Albert E. obviously. Now get up and back away from your monitor, as far as you can. Who is it now?

Grow into these trousers... >>

The more we study, the closer we get

A couple of weeks back I posted about our bizarre perception of reality regarding the strange Thatcher Effect.

Well, it's not just people who are mentally challenged by this phenomenon. Monkeys are too (I know I that's a picture of chimpanzees, which are apes same as ourselves; so behaving 'like a monkey' goes much further back in time).

Researchers from Emory University, Atlanta showed monkeys normal pictures of other monkeys, either upside down or right way up, until the first monkeys were shit-faced bored of looking at pics of other monkeys.

Then they showed them 'Thatcher effect' doctored images. The image upside down... still bored shitless. Image right way up... hey watzat? The monkeys noticed the difference and suddenly paid attention.

A subtle but insightful result. We all can tell something is wrong with these images, but not say what it is. It's important because troup/mate/sibling/offspring/friend verification is important for social groupings. Much of this is visual, especially in humans, and an individual's face is exactly who they are.

This confronted me a recently when I had to visit my doctor's surgery. I met someone I hadn't seen for years. Recognition was instant; but he called me by name and I could not remember his. I remembered the charity work we used to do, where he used to live, his zippo lighter, the pub where we used to meet up, his stint in the army, where we met up again, where he lives now, how many children he has. But I could not remember his name.

After I had seen my doctor and was leaving he was still there, 'See you later Brian' came from nowhere, and I still can't remember his wife's name.

Ramble over...
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Thanks to Cryptozoology Online for the HT and here's the reference:

"Thatcher Effect in Monkeys Demonstrates Conservation of Face Perception across Primates, Ikuma Adachi, Dina P. Chou and Robert R. Hampton", Current Biology (2009) in press (abstract only, unless registered). Grow into these trousers... >>

Our bizarre perception of reality

I used to have a page, torn from a magazine, showing a girl's face upside down (no smirking!). She looked really attractive till you turned the page the right way up. I always found it very disturbing and something which I could use to catch other people unawares (ie mindfuck).

It's called the Thatcher Effect, after some grocer's daughter.

Here's a great demo, without Thatcher.

Celebrities Look Better Upside down


And here's another to help explain it.

Head spin trick
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A most amazing optical illusion

Look directly at the falling ball and it falls straight down.

Look off to one side and it falls to the left.


You don't believe me do you? See it here. Grow into these trousers... >>

Happy birthday Charles Darwin

Now click over to Richard Wiseman's blog for a great Darwin illusion thing. Grow into these trousers... >>

A great new blog to visit

If you enjoyed the Amazing Colour-changing Card Trick you may be interested in a new blog by professor of psychology, magician and quirkologist Richard Wiseman. Though he's only been posting since the New Year, Wiseman's entertaining style is beginning to emerge as he writes on tricks, illusions and the unusual. This should a site to watch out for.

A word of warning though:
Tree Lobsters! - beware these posts. Grow into these trousers... >>

I want one of these

Forget lava lamps and oil wheels, I want one of these:

Time Fountain - Optical Illusion
Grow into these trousers... >>