eciprocity begins in infancy, when a baby is already learning that communication is a two-way street. By 8 months, a baby is on her way toward complex reciprocal relationships with caregivers. Infants start to communicate without the benefit of words. A smile gets a smile back, a frown gets a frown back. A joyful sound gets a gleeful look from parents. An angry sound gets a "What's the matter?" look from a parent. Even children this young initiate the exchange of facial expressions and respond to caregivers' facial expressions with their own.

By 12 to 18 months, reciprocity becomes even more complicated. Little Sally takes Mommy by the hand and walks to the refrigerator. Mommy watches to see what the child wants. When Sally points, Mommy looks puzzled. Then Sally bangs on the juice and says, "Uh, Uh," while pointing to herself. Mommy says, "Oh, I get it!" She takes out the juice and the milk and says, "Which one do you want?" Sally points to the juice. Then Mommy pours it for her. Note the multiple exchanges and the child's ability to communicate her needs without using words.

The capacity for reciprocity not only enables babies to communicate but to problem-solve as well. They can woo Mommy by giving her a big hug rather than just crying when they want something. Instead of having a tantrum and kicking, they can look angry and make angry sounds, so that Mommy will nod and say, "I understand, I'll get you your juice."

This growing ability to participate in reciprocal relationships also helps young children develop a sense of self. The growing awareness of self involves the recognition of all the things they want and all the feelings they have. They recognize Mommy as a separate person-she is the one who's funny or warm and tender. Daddy is the one who's this and that. The child begins to experience other people in her life as separate individuals. All this occurs by the second year of life.

Reciprocal interaction with gestures, as well as later with words and ideas, allows symbolic thinking to flower. By age 2 to 3, the child is building bridges between ideas, learning to answer such questions as:

Question: Why do you want to go out?

Answer: Because I want to play.

Question: Why do you feel bad?

Answer: He won't play with me.

As a child goes through the preschool years, she continues to use gestures and facial expressions, since keeping reciprocal interactions going in this way is quicker than with words. You can see if someone's frightened or sad or angry even before you process his words. For example, a teacher might give a child a frown to indicate, "you need to make a better choice." This develops important skills in preschoolers, including impulse control, because now they understand consequences. Some children understand the message right away, others don't. The children who don't are the ones who need more practice with reciprocal interactions.

Reciprocity also reinforces children's understanding of reality. A child can't live in an internal world of fantasies if she is getting feedback from someone outside herself. If a child is simply left alone and allowed to get lost in her own internal world, there is no way she can develop a sense of reality, which should be coming in between ages 3 and 5. So this back-and-forth exchange of words and gestures and emotional expressions helps children become reality-based. They learn to switch back and forth between fantasy and reality as needed.

When we take stock, we see that in order to make the most of peer interactions; to have cooperation in the classroom; to help children follow rules, learn impulse control, and learn to differentiate between reality and fantasy, reciprocity is essential.