Heavy use of pacifiers may limit the opportunity for baby boys to mimic the facial expressions of others and thereby disrupt their emotional maturity, according to a new study published in the journal Basic and Applied Psychology.

“(T)he way we communicate with infants at first is by using the tone of our voice and our facial expressions,” study author Paula Niedenthal of the University of Wisconsin-Madison explains in a press release. "What if you always had something in your mouth that prevented you from mimicking and resonating with the facial expression of somebody?"

The study was comprised of two separate tests. The first test examined a group of 6- and 7-year-old boys who had been shown a video. The boys who had been given pacifiers for a longer period of time were less likely to mimic faces shown to them on the video than their peers who had spent less time with pacifiers, Medical Daily reported.

The second test assessed the level of emotional intelligence of college students through an exam. The results were the same: Those who had been given pacifiers for longer periods of time had scored lower on emotional intelligence tests than those who hadn't.

Girls appeared to have been an exception to the findings, the study found.

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"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," Paula Niedenthal, a study author, said in the release. "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."

Further research is required, the Christian Science Monitor noted. Not all researchers agree that the ability to mimic facial expressions and the ability to perceive others' emotions are directly connected.

"So, if your baby boy really loves his pacifier — and you don't want to ask him to give it up — consider taking a lesson from "Up All Night's" Mr. Bob and playing a few extra rounds of very animated peek-a-boo," the Huffington Post noted.

Rachel Lowry is a reporter intern for the Deseret News. She has lived in London and is an English graduate from Brigham Young University. Contact her at or visit