Julia Galef over at Rationally Speaking:
[A] lot of recent research suggests that these metaphors operate below the level of conscious thought. In one study, participants who were asked to recall a past event leaned slightly backwards, while participants who were asked to anticipate a future event leaned slightly forwards. Other studies have shown that our metaphorical use of temperature to describe people’s demeanors (as in, “He greeted me warmly,” or “He gave me the cold shoulder”) is so deep-seated, we actually conflate the two. When people are asked to recall a time when they were rejected by their peers, and then asked to estimate the temperature of the room they’re sitting in, their average estimate is several degrees colder than that of people who were asked to recall being welcomed by their peers. And in one study that asked participants to read the dossier of an imaginary job applicant and then rate his or her personality, participants who had just been holding a hot object rated the imaginary applicant as being friendlier, compared to participants who had just been holding a cold object.
Another classic example is the “morality is cleanliness” metaphor. We talk about people having a clean record or a tarnished one, about dirty dealings and coming clean. And of course, religions are infused with this metaphor — think of baptism, the washing away of sin. One clever study published in Science in 2006 showed how deep-seated this metaphor is by dividing participants into two groups: those in the first group were asked to reflect on something virtuous they’d done in the past, and those in the second group were asked to reflect on a past moral transgression. Afterwards, each participant was offered a token gift of either a pencil or a package of antiseptic wipes. The result? Those who had been dwelling on their past wrongdoing were twice as likely to ask for the antiseptic wipes.
Associating the future with the forward direction and the past with the backwards direction seems pretty harmless. But cases like “morality equals cleanliness” start to suggest how dangerous metaphorical thinking can be. If people conflate dirtiness with immorality, then the feeling of “Ugh, that’s disgusting” becomes synonymous with the judgment, “That’s immoral.” Which is likely a reason why so many people insist that homosexuality is wrong, even though they can’t come up with any explanation of why it’s harmful — any non-contrived explanation, at least. As the research of cognitive psychologist Jonathan Haidt has shown, people asked to defend their purity-based moral judgments reach for logical explanations, but if they’re forced to admit that their explanation has holes, they’ll grope for an alternative one, rather than retracting their initial moral judgment. Logic is merely a fig leaf; disgust is doing all the work.