A customer wants 20 gift boxes of homemade marshmallows for Christmas. She wants them to sparkle. You say yes, and then you remember what marshmallows do in a box. They stick to each other, to the paper, and to everything...

Standing in front of a shelf of shimmer, most people pick the shade they can already picture in the glass. It is a reasonable way to choose and it is not the way the shelf actually moves. We can see...