The New York Times recently reported an investigation of harsh punishment doled out to students who were “acting out” in class. When I was growing up, unruly children were said to be “acting up.” What’s the difference?
According to Merriam-Webster, act up means “to behave in an unruly, recalcitrant, or capricious manner” or, in the case of mechanical objects, to “function improperly.” The Online Etymological Dictionary says the phrase has been in use in the United States since 1903.
Act out is a much more recent innovation, dating from 1974. Its use originated with psychiatrists, and it means to “behave badly or in a socially unacceptable, often self-defeating, manner as a means of venting painful emotions.”
So I suppose that everyone who acts out in this sense is acting up, but not everyone who acts up is acting out.
Act out, of course, has another meaning that predates its psychological usage, to “portray in action,” as acting out one’s beliefs or acting out a dramatic scene.
The Bard of Buffalo Bayou has been known (in his younger days) to find work as an actor in roles that no one else wished to play. When the Bard acts, it is not up, it’s down and out.
A lustful Shakespearean named Seth
Made love until quite out of breath.
He conquered Ophelia
As well as Cordelia,
But was stymied by Lady Macbeth.