In the classic John Ford western, The Man Who Shot
Liberty Valance, there is a traditional western shootout between an eastern lawyer, Rance Stoddard (James Stewart) and the vicious outlaw, Liberty Valance
(Lee Marvin). Valance’s first shot injures Stoddard and just as Valance is
about to finish him off, Stoddard manages to squeeze off a shot and Valance
falls, dead. Unknown to the characters and the audience, at that point in the
film, Valance was actually killed by Tom Doniphon (John Wayne), who shot a
fraction of a second after Stoddard. Had the situation been real, a witness
would have heard a single shot and thought that it was Stoddard’s gun that
killed Valance.
This sonic illusion, called the precedence effect
illusion (PEI),