How much would that be? In answer I guess most people would offer something that would depend on visual acuity, or the absence of visual obstruction. While it seems perfectly normal that what you see is what you percieve, quite the opposite is true.
A recent physics article in physorg.com explained it as follows:
This is a consequence of the eye's main characteristic, namely as a detection threshold. Below a certain threshold number of incoming photons, the eye remains blind (no light is seen), whereas above the threshold the efficiency (i.e. the probability of seeing) is close to one.
In their calculations, the authors also considered the influence of experimental imperfections, such as photon losses, which are inevitable in a real experiment. They found that the setup is surprisingly robust. A strong Bell violation can be obtained even in case of high losses, demonstrating the presence of entanglement. This is a very astonishing feature since entanglement is generally an extremely fragile property, highly sensitive to experimental imperfections such as losses.
I may have this wrong, but what I think it means is that our eye’s make things up, in this particular case it is photon’s, but it could be just about anything you see.
If you can imagine your perception as a flat screen TV in which there are increasingly more pixels dead, our perception of the degrading picture will remain as it was without any dead pixels.
But perception is not the only ability that can be influenced by entanglement? It also plays a role in something known as the placebo effect.