optical illusions

Some restaurants want to make their portions look bigger. Others may want to seem to deliver a modest portion while still satisfying hungry diners. For years, chefs have exploited what's known as the Ebbinghaus illusion to push the…

Stare at a lightbulb for a few seconds, and when you look away you'll see a colored spot no matter where you look. That's an "afterimage," and these ghostly remains of what you are looking at can be much more interesting than a mere…