Interruptibility of speech
Peter Ladefoged, Robert Silverstein, George J. Papcun · The Journal of the Acoustical Society of America · 1973
Experiments were conducted on the ability of a speaker to interrupt himself when given a cue to do so at unexpected moments. There seems to be no particular point in an utterance when a speaker finds it harder to stop saying what he originally intended to say and start saying something else instead. Just before an utterance, while a speaker is planning the articulations, there is a period during which he cannot readily plan another utterance, but he can perform nonspeech gestures.