<p>Looks like these are variations on the Hermann grid illusion, wiki page here: <a href="https://en.wikipedia.org/wiki/Grid_illusion" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Grid_illusion</a></p>

<p>As the wiki page notes, the first-pass explanation of this was lateral inhibition, but this is not really 100% satisfactory. 
There's a nice quick walk-through of the old explanation and the problems with it here: <a href="http://web.mit.edu/bcs/schillerlab/research/A-Vision/A15-2.htm" rel="nofollow noreferrer">http://web.mit.edu/bcs/schillerlab/research/A-Vision/A15-2.htm</a> 
A journal paper version of this stuff from the same lab is:
Schiller, P. H., &amp; Carvey, C. E. (2005). The Hermann grid illusion revisited. Perception, 34(11), 1375-1397.</p>

CC BY-SA 4.0
2018-08-24T21:29:38.030Z
2018-08-24T21:29:38.030Z
steveLangsford
<p>How does neuroscience explain the following optical illusion? Look at tiles. You will see spots of shadow near all corners. The shadow will be missing from some corners very near the center of your attention.</p>

<p>So, the brain has ganglia that detect horizontal and vertical edges as well as more complex edges. They work best with high contrast edges. That's all I know right now that might be relevant. Thanks in advance. </p>

<p><img src="https://i.sstatic.net/Zza8M.png" alt="tiles">
<img src="https://i.sstatic.net/ogluE.jpg" alt="tiles in a bathroom"></p>

<neuroscience><perception><vision><optical-illusion>
Why do we see shadows in the following black-and-white optical illusion?
Peter Blackson
# Why do we see shadows in the following black-and-white optical illusion?

(Asked by: username_0 on 2018-08-24)

How does neuroscience explain the following optical illusion? Look at tiles. You will see spots of shadow near all corners. The shadow will be missing from some corners very near the center of your attention.

So, the brain has ganglia that detect horizontal and vertical edges as well as more complex edges. They work best with high contrast edges. That's all I know right now that might be relevant. Thanks in advance.

![tiles](https://i.sstatic.net/Zza8M.png)
![tiles in a bathroom](https://i.sstatic.net/ogluE.jpg)

**Tags:** neuroscience, perception, vision, optical-illusion


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## 1 answers

### Answer by username_1 on 2018-08-24. Score: 2

Looks like these are variations on the Hermann grid illusion, wiki page here: <https://en.wikipedia.org/wiki/Grid_illusion>

As the wiki page notes, the first-pass explanation of this was lateral inhibition, but this is not really 100% satisfactory.
There's a nice quick walk-through of the old explanation and the problems with it here: <http://web.mit.edu/bcs/schillerlab/research/A-Vision/A15-2.htm>
A journal paper version of this stuff from the same lab is:
Schiller, P. H., & Carvey, C. E. (2005). The Hermann grid illusion revisited. Perception, 34(11), 1375-1397.


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