If you want your infant son grow up to be a perfectly emotionless
universal soldier, then you might want to start by making sure he spends
most of his time with a Binky in his mouth. According to a new study from the University of Wisconsin-Madison, that pacifiers stunt the emotional development of baby boys by robbing them of the opportunity to mimic adults.
Since a big part of learning emotional cues for infants involves
observing and mimicking adults' facial expressions, too much pacifier
time for baby boys might actually be preventing them from engaging in a
key stage of human emotional development.
Based on their study, the researchers found that men who spent a lot of their time with their pacifier as infants scored significantly lower than their peers on a test of perspective-taking, which is a key component of empathy. Additionally, researchers found that six to seven-year-old boys who spent more time sucking on pacifiers as infants were less likely to mimic the emotional expressions of faces in a video. Remarkably, girls who had similar heavy pacifier use didn't experience the same emotional lag. This suggest that the different ways in which girls develop could mean that they've already acquired sufficient emotional intelligence.
The researchers also speculate that gender normative parenting might also have something to do with the difference between the effects pacifiers have on boys and girls:
It could be that parents are inadvertently compensating for girls using the pacifier, because they want their girls to be emotionally sophisticated. Because that's a girly thing. Since girls are not expected to be unemotional, they're stimulated in other ways. But because boys are desired to be unemotional, when you plug them up with a pacifier, you don't do anything to compensate and help them learn about emotions.