I can't believe I'm going to join in this fray....

The bottom line is those lines look sloped. All the science in the world isn't going to make them look straight. The same can be said for audio illusions. Just because something can be scientifically measured to tell you it should sound a particular way, doesn't mean it's going to sound that way to you.

I'm not trying to join either camp on this issue, but your optical illusion example doesn't really help your case.

OK...that's the last I'm posting on this. I feel dirty now...I've got to shower.