To investigate the effect of mortality awareness, researchers behind the influential "terror management theory" first experimented with judges and prostitutes.
Studies on how we cope with the inevitability of death, or terror management, have a fundamental flaw -- they lack a control group. It's impossible to test if or how a person changes their beliefs or behavior when reminded of their mortality, because our awareness of this human condition never ceases. Our brain's superfrontal gyrus sees to this neurologically, while culture and our physicality highlight it further with books like the Bible and with every new wrinkle.
To examine death despite this conundrum, psychologists at the University of Kansas in 1989 did what academics do best: they rationalized the problem away. Just as philosopher Jean-Paul Sartre affirmed man's existence through his own Cartesian tautology ("I am, I exist, I think, therefore I am"), Jeff Greenberg, Sheldon Solomon, and Tom Pyszczynski simply assumed that there is a universal, baseline cognizance of the threat of death, and then investigated the instances when death was on people's minds more than usual.
Decades later, hundreds of published academic papers have shown that worrying about death affects everything from our prejudices and voting patterns to how likely we are to exercise or use sunscreen. More broadly, they've proven Greenberg and company's original terror management theory right all along: that people deal with death by upholding worldviews that are larger and longer-lasting than themselves, and opposing anyone or anything that violates these "cultural anxiety-buffers."