Bug illusion

[King_Cool]

I have ben bugged the last coupple of days with what i thought was a bug ( graphical ) in my application.
The so called bug turned out to be nothing more than an optical illusion
...
How many of you can see the illusion?

[gkinfinity]

Haha when I looked at that I was thinking nah man, it looks like you did something wrong. But you're right, it was just a weird illusion

[LB]

What is the illusion? Whether or not the 'curtain' is down, the red square is ahead of the grey rectangle. Is this intended?

[gkinfinity]

It's not though. The counter on screen displays the differences in their x coordinates and it never changes

[LB]

Weird, the counter changed for me the first time, now it just stays at negative fifty-eight the whole time. But I swear I fluxuated between -80 and -76...guess it was all part of the illusion

[King_Cool]

Weird, the counter changed for me the first time, now it just stays at negative fifty-eight the whole time.

Mine stays at -78, are you sure you didnt move anything around?
...
It does not matter that i know its an illusion, no matter how many times i look at it.
I cant believe my mind is doing this to me

I wonder whats the reason for this? Obviously something to do with colors or contrast
Maybe ill make a habbit of not using a white background

[gkinfinity]

Yeah it stays at -78 for me too. And you're right, the illusion is a result of the colors you chose

[DavidN]

It occurs to me that I don't actually know if modern LCD displays are composed of individual side-by-side RGB components or not... but if they are, it might be something to do with the way that entirely red shapes may appear a tiny distance (1/3 of a pixel) slightly further to the left than those made up of all three colours equally, and the movement tricks your eye into exaggerating that distance.