I know, it sounds like it should be related to the MacGuffin, but it isnt… Whether they know the name or not, the McGurk Effect is very well known to most ADR Editors eg when a director wants to change an onscreen line & tries to put different words in the mouth of an actor… No matter how well performed & edited the new line is, your brain just doesnt accept it as true/real/honest, and that is dangerous territory to be in for any film maker as it can abruptly destroy suspension of disbelief, or even worse just slowly undermine it…. As a very simple example watch this video & take particular note of what the actor is saying:
direct youtube link for iphone/ipod touch
Ok now play the clip again, but shut your eyes & listen with your ears only… See?
The McGurk Effect also explains why I would much rather read subtitles on a film than have it dubbed into english – no matter how good the sync is!
Thanks to Carl for the link!