Hey Ray: Simultaneous Brightness Contrast
PITTSBURGH (KDKA) - Seeing is believing...Most of the time.
In the past, we have shown you some illusions, and we have another illusion that will really trick your eyes! To get started, we are going to change everything to black and white!
Take a good look at the two dots on your screen. What do you notice about them?
Elizabeth: The one on the left is darker than the one on the right.
That is incorrect. Look again.
As you look at this image, you may agree with Elizabeth, but look at what happens when I take away the background. The two dots are exactly the same color.
We can show you this experiment in different ways, so you don't think this is some sort of editing trick.
Like in the video that accompanies this story, we can have one dot move from one side of the screen to the other. I assure you that the dot's brightness did not change, even though it appears to become lighter.
We can show you multiple dots moving across your screen, but they all seem to change in brightness, too. You might still think these are editing tricks so how about we add a line that is the same color as the dot and stretch it across your screen?
Once you add in the background, the bar even seems to change in brightness from one side of the screen to the other. The dot nor the bar changed brightness at any time, though.
The dots and bars seem to change in brightness because of something called "Simultaneous Brightness Contrast."
According to the National Center For Biotechnology Information, Simultaneous Brightness Contrast is a phenomenon where two things of equal brightness appear differently when one is on a light background and the other is on a dark background. Simultaneous brightness contrast is not learned. We're born with it, and scientists believe this is important for us to make photometric judgments. That means it helps us notice things that would otherwise blend into the background.
You can see one of the paper dots looks brighter than the other. The dots will seem to change in brightness as they are moved across the paper, too. It is an illusion because you were born with Simultaneous Brightness Contrast.