![neurolove:
FLASHBACK-[Image Source]
What color are the centers of the white lines crossing?
This is a type of optical illusion. How do these optical illusions work? There have been a few different explanations proposed for this, but I like the simple/oldest one. Our brain uses information from the eyes that relies on lateral inhibition. This means that several photoreceptors (the things that perceive light) talk amongst themselves and send on a signal based on the contrast of an area (dark vs. light, though you can also do colors vs. other colors). They typically do this in circular patterns where one photoreceptor is the “center” and other photoreceptors are the “surround” (a circle around the center). Think of stars at night- they are white in a dark sky. These would maximally excite a group of cells that integrate the information from the photoreceptors (the one in the center sees light while the ones in the surround see darkness). Because of lateral inhibition, the signal would be extra strong when there is better contrast (as in the case of stars- or in the reverse kind, of dalmatian spots) and less strong when there is not as much contrast (think of a big gray sheet). You have the best vision when you look straight on where lots of photoreceptors are concentrated, but in the outsides of your vision, it’s not as concentrated and the receptive fields (how much of the world you perceive with each cell) are larger.
In this illusion, you have some photoreceptors whose fields will be with the center dots and have that complicated white and darker surround that is crazy kinds of contrast- too much contrast within the surround that can’t tell the center what is going on properly. Your photoreceptors are trying to have that inhibitory struggle to define where the dark and light are but can’t do a perfect job of it as you get further from the fovea (the place where photoreceptors are most concentrated), which is why the crosses look gray. I know it’s complicated, but I will try to explain more about vision later.](http://25.media.tumblr.com/tumblr_m09mmditGo1qb6etto1_400.jpg)
La fixette de l’hôtelier helvétique, c’est donc le canard #hypothèseconfirmée http://t.co/NwqbBelk
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La fixette de l’hôtelier helvétique, c’est donc le canard #hypothèseconfirmée http://t.co/NwqbBelk
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Aller, du trouble musculo-squelettique pour tout le monde : Les DRH craignent un climat social explosif en 2012 http://t.co/wQu6hNt9
Aller, du trouble musculo-squelettique pour tout le monde : Les DRH craignent un climat social explosif en 2012 http://t.co/wQu6hNt9
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Sujet du jour #Celsa : faut-il pendre les planneurs ? Finalement ? Si ça ne tient qu’aux étudiants, on peut même brûler l’agence avec #fête.
Sujet du jour #Celsa : faut-il pendre les planneurs ? Finalement ? Si ça ne tient qu’aux étudiants, on peut même brûler l’agence avec #fête.
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RT @lemondefr : “Ce qu’il ne faut pas dire au niveau du langage” http://t.co/eSH5iTkd
RT @lemondefr : “Ce qu’il ne faut pas dire au niveau du langage” http://t.co/eSH5iTkd
