When you're watching a thriller or horror film there is usually a moment when you think 'what sane person would actually do that?'. Classic examples include; the hero goes to confront the villain on his/her own, unarmed and without telling anyone where they're going. Another is when someone is all alone in a spooky situation, often knowing full well there is a villain / monster abroad and they hear a noise. What do they do? Shout out 'Who's there?' This, of course, alerts the villain to where their next victim can be found. I'm sure you can think of many more examples.
So, my question is this. Are these characters particularly stupid purely for the purposes of the script or would real people behave like that?