Gut Check Meaning

Example : 1996 June 9, Paul Rodgers, "Two born-again brands: one yells, one whispers," Independent (UK) (retrieved 23 Aug 2015):  "I told them what we needed was a gut check to see whether we had the stomach to go ahead."2000 Oct. 7, Nancy Gibbs, "Gore: Where Is The Love?," Time (retrieved 23 Aug 2015):  There's an old parlor game, a kind of gut check for the heart and head. Would you rather be rich or pretty? Happy or famous? Is it better to be good or to be smart?2013 Jan. 18, Stephen J. Ciccone, "January’s Stock Temptation," New York Times (retrieved 23 Aug 2015):  But for investors looking for long-term winners at the start of the year, it’s best to give yourself a gut check before you buy.2014 Sep. 9, David Ignatius, "Stepping warily onto the battlefield," Washington Post (retrieved 23 Aug 2015):  For President Obama, this is gut-check time on Iraq. He is moving the nation back onto a pitiless battlefield, with a war plan that is long on good intentions and short on clarity about the ultimate mission.