Anacoluthon is beginning a sentence in one syntax, but ending it in another, usually with an unexpected shift in subject. For example: “I told you not to play by the river–where did you get those coins?” Or, “Drive carefully. There’s a bump in the–I’ve said enough.”
Anacoluthon is not a non-sequitur (Latin for “it does not follow”). Anacoluthon is a stylistic error or a deliberate rhetorical statement. Anacoluthon is an interruption in sentence structure, with disjointed thought process.
A non-sequitur is jumbled thoughts with faulty logic. A non sequitur doesn’t follow a sequence of events and usually doesn’t make sense logically. For example: “I’m intuitive like a statue.” “The murder took place on the marina. Vivien sits at a park bench there every day. She must be the murderer.”
Fiction writers can use both anacoluthon and non-sequitur. If two characters are talking, one tries to change the subject because of a secret that could be revealed if they continue. That character would use anacoluthon, “Then I went to the flower shop–is that a new hair style you have?”
A non-sequitur could be used when a detective questions a witness who might say, “I saw a man’s shadow pass my apartment window. Jake looked in the window of Eve’s shop last week.That man must have been Jack.”
Have fun using anacoluthon or non-sequitur.