As a British disgustologist visiting the USA this month, I was struck by all the Halloween decorations. Why did almost every porch sprout pumpkin skulls, gravestones, body parts, bloody cleavers, witches, zombies, spiders and ghouls? Why so many Halloween party shops and shelves of disgusting worm-shaped candy? And, for that matter, why—Halloween notwithstanding—do Brits, Americans and other nations alike, seek to entertain themselves with the nasty, the scary, the gory and the repulsive? What’s the attraction of an Alien bursting from a gut or an explosion of bloody bodies in a Tarantino climax? Why did Grand Theft Auto, which lets players kill with baseball bats and cannibalise corpses, gross a billion dollars in three days?
Halloween has a long cultural history, as a festival of the dead, as ritual to placate marauding spirits, as a harvest celebration and as a chance for kids to party. But, as with most cultural phenomena, it is underpinned by a number of basic human emotions. So let’s untangle the motives that are at play here.
First of all fear. Halloween is Fright Night, when the ghosts of the dead are supposed to scare us and when we watch thrillers about axe murderers. Although we learn what specific things to fear, fear is a part of human nature. And, of course, we are not the only species to be fearful. This is a motive with a simple job to do, to keep animals from being eaten by other animals. When an ant flees an anteater, when a chaffinch freezes in the presence of a sparrowhawk, or when a gazelle flees a hyena, their fear system is engaged. The system focuses attentional resources on the danger and it motivates evasive action. Without such systems all prey species would have been eaten and would now be extinct. Humans are no exception; it’s a fair bet that you are descended from a long line of fearful people. Ancestral voices tell us to beware; to freeze or flee in the presence of dangers. So why do we fear fantastical monsters, ghosts and zombies? Powerful emotions create powerful associations. The grass shivers—is it a snake? A twig snaps—is it the next door tribe on a raid? That strange-acting local woman—did she use witchcraft to kill my brother? And is that eerie whisp of smoke the evil spirit that carried off my infant?
Another emotion besides fear is engaged at Halloween. Disgust is an adaptive system that works in the same way as fear, but its object is not the large predators that want to eat us up from outside, but the tiny parasites and pathogens that want to eat us up from inside. We all recoil from human wastes, from oddly shaped people, from signs of illness and infection and from people who are unhygienic. And one bad experience with sick-making food or a foul smell can create a bad association for life. Zombies, body parts and axe murderers not only cue fear but they also smack of infection. Green skin, open sores, bloody wounds, body parts, worms and sticky goo all need to be avoided because they could be a source of infectious disease. Hence we find them disgusting. The emotion of disgust sticks to nasty, smelly contaminated objects; a plastic poo is hard to countenance even if we know it is inorganic.
So Halloween decorations cue fear and disgust. But, hang on—surely plastic porch decorations arn’t so much disgusting or frightening, but fun. They made me smile and laugh, not run or puke. What’s going on here? Again, evolution provides the answer. Though we humans are like our animal ancestors in many ways (including having disgust and fear systems) in one important way we differ. We have a very long period of adolescence, and in that period our main task is to learn. To learn to become a brave warrior you have to know what it feels like to wound, maim and kill, and to learn to be socially acceptable you have to know what disgusts people. We all like to take our emotions out for a spin, especially when it’s quite safe to do so (for example plastic decorations or aliens projected on a screen). Thats what the 'play' motive is for, to make us want to learn stuff that we can store up for later use in the real world.
Halloween has deep cultural roots and has spread across the globe. But it has its origins in three even more ancient universal motives: disgust, fear and play. Trick or treat anyone?
More on the anatomy of motivation