September 19, 2012: When a baby mimics the facial expressions of the people around him, the mimicry, research has shown, "triggers activity in the brain that allows the baby to feel the emotion being expressed."
"When [a person] makes that facial expression, [he] starts developing those feelings [himself]," says Paula Niedenthal, at left, a psychology professor at the University of Wisconsin-Madison, and lead author of a new study, announced today in the Wisconsin State Journal, that has found that boys who used pacifiers as babies scored lower on tests that measured their emotional development. Because...the pacifier prevented them from mimicking facial expressions. (The research, which was supported by the French Agence Nationale de la Recherche, was published today in the journal Basic and Applied Social Psychology.)
Niedenthal said studies on girls did not show the same phenomenon. She said that may be because of societal norms that prompt parents to work harder at encouraging the expression of emotion in girls.
Niedenthal has specialized in studying the connections between emotions and physical behaviors such as expressions. She compared her work with babies and pacifiers to studies that have shown people who use Botox, which paralyzes facial muscles, have a more limited range of emotions and also have difficulty recognizing the emotions behind others' facial expressions.
But her current research had a much less scientific origin. Her own three boys did not use pacifiers, Niedenthal said. She recalled a dinner at which her 3-year-old son was throwing a fit. She noticed that another child at the table, who was using a pacifier, did not respond to her son's flailing tantrum.
"The parents took the pacifier out, and the child still did not respond," Niedenthal said. "That's when I got the idea for this research."
News & Notes of the College of Letters & Science of the Univ. of Wisconsin reports:
“What’s impressive about [the results of this research] is the incredible consistency across those three studies [6- and 7-year-old-boys; college-aged men; group of college students] in the pattern of data,” Niedenthal says. “There’s no effect of pacifier use on these outcomes for girls, and there’s a detriment for boys with length of pacifier use even outside of any anxiety or attachment issues that may affect emotional development.”
Girls develop earlier in many ways, according to Niedenthal, and it is possible that they make sufficient progress in emotional development before or despite pacifier use. It may be that boys are simply more vulnerable than girls, and disrupting their use of facial mimicry is just more detrimental for them.
“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,” Niedenthal says. “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.”