We were at the eye doctor to have Dorothy assessed for glasses. Dorothy was looking through the lenses, and asked, "Can I have a minute before I look with this eye? I'm still seeing the afterimage from when you shined the flashlight."
"I'm impressed that you know the word afterimage. Who's the scientist in your family?" the doctor asked.
"I like optical illusions," Dorothy explained, "and the illusions often involve afterimages."