Scientists are now saying pacifiers could stunt boys' emotional development

A team of psychologists from the University of Wisconsin-Madison found that heavy pacifier use was linked to poor results on various measures of emotional maturity. A lot of the way we communicate with infants at first is by using the tone of our voice and our facial expressions. With a pacifier in their mouth, a baby is less able to mirror those expressions and the emotions they represent -- and mimicry can be an important learning tool for babies. 'By reflecting what another person is doing, you create some part of the feeling yourself,' said lead author Professor Paula Niedenthal.