Somebody Else's Problem field

The letters stand for "Somebody Else's Problem". An SEP field can be erected around a bizarre and unbelievable scene so that the minds of the viewers instantly assert that it's "somebody else's problem", and therefore don't perceive it at all. The primary example given in the Hitchikers Guide is when a UFO lands in the middle of a cricket ground during a match, and the assembled crowd fails to notice it.

See also: bystander effect[?]