[BITList] The train track optical illusion that's bewildering the internet - BBC News

[John Feltham]

> http://www.bbc.com/news/blogs-trending-35989211?ns_mchannel=email&ns_source=inxmail_newsletter&ns_campaign=news_magazine_080416 <http://www.bbc.com/news/blogs-trending-35989211?ns_mchannel=email&ns_source=inxmail_newsletter&ns_campaign=news_magazine_080416>
> 
> The train track optical illusion that's bewildering the internet
> 
> This video - of a father shuffling around his son's toy train tracks - has bewildered the internet. Can you figure out what's causing the optical illusion?
> 
> It was posted on Twitter by BBC trainer Marc Blank-Settle <https://twitter.com/MarcSettle/status/717812888740761600> on Wednesday evening, and been shared thousands of times since then.
> 
> The track on the bottom appears to be much longer than the one on the top, but when one is placed on top of the other, its clear that they are in fact the same size.
> 
> Many viewers were left completely dumbfounded.
> 
>  @StefanEJones / Twitter
>  @LodovikoZ / Twitter
> But - assuming that aliens aren't actually to blame - what causes the unusual effect? Others on Twitter were quick to point out the answer.
> 
>  @tomstafford / Twitter
> The Jastrow Illusion <http://www.michaelbach.de/ot/geom-Jastrow/index.html> is an optical illusion first defined by an American psychologist, Joseph Jastrow, more than 100 years ago. It involves two arc shapes of equal size, where the longer side of one arc is brought into contrast with the shorter side of the other.
> 
> When the images are arranged as they are in Marc's video, the top left corner of the lower piece is actually shifted over to the right, to align with the bottom left corner of the piece on top.
> 
> This image should help shed some light on the mystery.
> 
>  Jastrow Illusion
> Many of the people keen to explain the optical illusion said they remembered it being the first they were taught about in school, or even the first they had spotted when playing with similar toys as children.
> 
>  @vr_ml / twitter
> Next Story: Music fans share most embarrassing memories in Indie Amnesty <http://www.bbc.co.uk/news/blogs-trending-35980791>
>  Getty Images
> Music fans share most embarrassing memories in Indie Amnesty READ MORE <http://www.bbc.co.uk/news/blogs-trending-35980791>
> You can follow BBC Trending on Twitter @BBCtrending <https://twitter.com/BBCtrending>, and find us on Facebook <https://www.facebook.com/pages/BBC-Trending/832942320102956>. All our stories are at bbc.com/trending <http://www.bbc.co.uk/news/blogs/trending/>.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bcn.mythic-beasts.com/pipermail/bitlist/attachments/20160411/3d093bc4/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: _89126241_6384d0c3-37bf-4e64-aa74-56f4d0d0eec7.jpg
Type: image/jpeg
Size: 20468 bytes
Desc: not available
URL: <http://lists.bcn.mythic-beasts.com/pipermail/bitlist/attachments/20160411/3d093bc4/attachment-0002.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: _89126243_5f9f6c2e-10fc-48d8-b6f6-f5e4c383aeb1.jpg
Type: image/jpeg
Size: 31256 bytes
Desc: not available
URL: <http://lists.bcn.mythic-beasts.com/pipermail/bitlist/attachments/20160411/3d093bc4/attachment-0003.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: attachment.gif
Type: image/gif
Size: 51 bytes
Desc: not available
URL: <http://lists.bcn.mythic-beasts.com/pipermail/bitlist/attachments/20160411/3d093bc4/attachment-0001.gif>