It might be nice to think of ourselves as rational beings with a strong and unyielding moral compass but science suggests otherwise. Our emotions, physical health, recreational habits, and, apparently, diet can all play havoc on our conscience, manipulating our ability to make fair moral judgments.
Researchers at the University of British Columbia in Canada found that when people were given ginger (valued for its anti-nausea properties), their judgments on different moral quandaries – from drinking water from an unused toilet bowl to talking to an ex behind your partner's back – were less harsh than those of a control group offered sugar pills. Their paper has now been published in the Journal of Personality and Social Psychology.
In a series of double-blind studies, volunteers were given either a ginger capsule or a placebo pill. For the first study, 242 participants were asked to rate how disgusted they felt when presented with a sequence of objectively disgusting photos, from rotten meat (moderately disgusting) to a man vomiting in a toilet (highly disgusting).
In the second, 306 were asked to rate how wrong they found possible "purity violations", a highly severe example being marriage between cousins and a moderately severe example being a morgue worker touching the open eye of a corpse.
The third was a replication of the second with a larger sample (497) and the fourth required 504 participants to again rate their disgust reaction to a series of moral dilemmas. But instead of being restricted to "purity violations", participants in the fourth condition were asked to make judgments on a range of situations, including harm/care (e.g. slapping a classmate unprovoked), fairness (e.g. cheating in a test), loyalty (e.g. a woman not attending a parent's funeral because they had been fighting), authority (e.g. a teenager slashing a cop's tires), and purity moral infractions (e.g. a man eats his dog after it was killed in a car accident).
The results show that when a participant had been given ginger they were less judgmental of moderately disgusting and severe images and situations, but not so of highly disgusting and severe images and situations. This suggests that the anti-nausea properties of ginger (and feelings of nausea more generally) do sway our moral decisions, at least to a certain extent, putting weight behind the idea that when it comes to issues of conscience, we are guided by gut feeling.
Fortunately, we are not entirely beholden to what we've had for dinner – the properties of ginger appear too mild and cultural ideas of morality too ingrained to have a noticeable effect on the more severe vignettes.
"This provides pretty good evidence that when we make moral judgements about purity, part of what we’re doing is thinking about how sick we feel," Jessica Tracy, a professor of psychology at the University of British Columbia, told New Scientist.
Remember that next time you tuck into a slice of ginger cake.