How similar is your idea to something I already know about or to a problem I have already solved?”
If audience members discover that the answer is close to what they had earlier guessed, they wil mental y check out on you. They wil experience a quick ping of self-satisfaction at the moment of realization, just before they mental y check out.
But checking out is not just a catch phrase to describe drifting attention or wandering minds. Checking out, in this context, refers to something very specific: an extreme and nearly total loss of alertness, and this is exactly what you need to avoid