Although we don't always realize it, little kids can understand the emotions behind our facial expressions and can (usually) figure out how to respond to them. In fact, a recent University of Washington study found that toddlers can even react to facial expressions that are directed at other people.
At around 18 months, kids start exerting their independence and testing cause and effect, says Lorraine Taylor, Ph.D., assistant professor of psychology at the University of North Carolina at Chapel Hill. When your child throws cereal from her high chair, for instance, you'll probably make an irritated face in response. A few throws later, your toddler will see that it's her actions causing the annoyance and realize you want her to stop.
To use her new ability to your advantage:
Shoot her "the look." Next time she's preparing to throw a fit in public, give her a warning look. Chances are she'll remember the last time you made that face at her -- and what the consequences were for ignoring it.
Put on a happy face. Reinforce good behavior with a smile. She'll soon learn that a grin means she can continue doing what she's doing.
Wear a poker face. Even if you don't tell your toddler that you're sad or worried, if your face shows it, she'll pick up on it -- and become uneasy. So keep your expression neutral when you don't want to pass on your emotions to your child.