Capitol Studios' staff engineer John Palladino created the process at the request of the record companies.
In some cases, the effect was enhanced with reverberation and other technical tricks, sometimes adding stereo echo to mono tracks in an attempt to fool the listener.
It was used for some of the biggest Capitol releases, including albums by The Beach Boys and Frank Sinatra.
An example is the Beatles' stereo mix of the song "I Am the Walrus", where the first portion of the piece is true stereo, but switches to artificial stereo at approximately the two-minute mark for the remainder of the song; this is because the live radio feeds from a BBC broadcast of King Lear were mixed directly into the mono mix of the song, and could not (with the pre-digital technology of that time) be extricated and discreetly superimposed onto the stereo mix.
However, the 1999 album Yellow Submarine Songtrack features a full stereo remix of the song, and the 2009 remaster of the original 1969 album restores the song to its original mono mix because enhanced stereo had fallen out of favor.