Do You Understand Zippers?

Art Markman explores the psychology of "unknown knowns:"

Find an object you use daily (a zipper, a toilet, a stereo speaker) and try to describe the particulars of how it works. You're likely to discover unexpected gaps in your knowledge. In psychology, we call this cognitive barrier the illusion of explanatory depth. It means you think you fully understand something that you actually don't. We see this every day in buzz words. Though we often use these words, their meanings are usually unclear. They mask gaps in our knowledge, serving as placeholders that gloss concepts we don't fully understand.