I got it 100% right :
Can You Pass This Tricky Eye Test? | Playbuzz
This one it's different than the two I did in past, but it's a similar principle. And like the two earlier I won perfect.
Some images are too small, with some JPEG artefacts making difficult.
The red test, the most difficult, it's easier looking to the HD version instead of the main test tinny images, where artefacts size became not relevant.
http://cdn.playbuzz.com/cdn/e99f31fc...aed317d035.jpg
So... the test itself prove artefacts are bad thing, even when minimal.