Your eyes see waves of light, not coloured squares.

Without my glasses? 480p.

Are you sure they are not seeing particles of light?

@bugrimmar, you cannot equate human vision to a resolution unless you specify the distance and size.  I imagine there is a visual maximum your eyes are capable of seeing, but it is definately not measured in resolution.

 The individual will also be a variable, perhaps listed by age or some such.

It is dependant on your eyesight, so I asume they are going off 20/20. As to those people who keep saying that you don't see in pixels, that is not the point. The original poster is asking how much detail in an HDTV a human eye can process.

Its kinda like how many frames per second a human eye can process.

How many gigs is the human brain?

It depends on how far you're from the TV, as someone's link shows.

If your face is glued to the screen, you can distinguish the pixels and even the subpixels (red/green/blue). If you're far enough, you can't tell 480p from 1080p.

And what OS does your heart use?

I think it's like 4 terabytes

And there was a similar thread about this subject a few months ago, if you go here it might give you the answer you want.