More about the Fovea.

So, my first post so long ago was on the fovea, even if I didn't refer to it as that. I ended it with "let's see what else we can come up with!". And so, just recently I did.

It's a hypothesis of the vaguest sort, and I expected to be dismissed or disproved by everybody I discussed it with...but my visual perception professor didn't dismiss it, nor has anybody else. Still, I offer it up with this caveat: I might be wrong.

I was reading my VisPerception course packet and they went over all of the well-known optical illusions. As I was experiencing them, I was asking myself what everybody does when viewing illusions: "How can I be experiencing something so wrong?" It is pretty rare we get confronted with just how easily our perceptions are fooled.




I tried looking at this illusion with the knowledge of the fovea: that everything we see is a tiny piece of sharpness in the center of a blur and I realized something.

We don't see it like that. We see it like this.

And that makes all the difference.

The other line is actually just a rough approximation of the line that's actually there. We can't see them both at the same time. And while our eyes saccade from one to the other, our peripheral brain is constastly swapping out what it thinks about the other...based on a rough guess of a blurry image.

A hopfully clear description of the entire process:
We look at one end of one of the lines, the left end of the top line like in my fovea simulation. The blurry ends we have of the other line is much further away from the only landmarks we have, the diagonal lines. Our brain tags it as "a longer line". If we then move our eyes over to an end of the lower line, we'll notice that the inverse is true: the blurry line is "shorter". Our brain is confident because it got many rounds of confirmation.

Try this. Look between the two horizontal lines so that all the edges are in your peripheral. You won't be as fooled.

Like I said, the fact that my explanation seems "simple" and "easy" compared to the explanation in the Visual Perception course book (which said that the diagonal lines became depth cues and we viewed it with 3d and perspective in mind.) makes me feel like a bit of a crackpot. Still, I think looking at the world with the knowledge you have a fovea is a real eye-opener.

That's not a pun because it's used literally.