Only during a baby's first month is its cry purely physiologically linked; from then on emotions are involved. Emotional contagion has been observed in children as early as two days after birth.

Milestones of Development:

1. 1-3 months: Infant gains the ability to raise his/or her chin from the ground and can turn head from side to side and play with hands and fingers.

2. 4-6 months: Baby rolls over. At five months, the child reaches and grasps while sitting on someone's lap. At six months, the baby sits alone and may stand with support. First teeth appear between five and nine months.

3. 7-9 months: Coordination improves. Creeping and crawling usually begin between eight and nine months.

4. 10-12 months: Child pulls himself/or herself up to standing position with furniture and walks with help.

5. 15 months: Baby stands alone then gains ability to walk. He/or she throws things.

6. 18 months: Toddler can walk sideways and backwards.

7. 2 years: Child walks with a steady gait, jumps, runs in a controlled way, and can climb stairs with help.

8. 3 years: Typically toilet trained, child dresses and undresses with simple clothing and can scribble.

9. 4 years: Child prints first name; he/or she has a stable preference for right or left hand.

10. 5 years: Youngster coordinates movement to music.

11. Middle childhood: Gender differences appear. More physically mature than boys of the same age, girls are superior in skills requiring flexibility, agility, and balance. Boys are stronger and perform better in activities that require gross motor movement. For boys, early maturation improves popularity and adjustment. Late maturing boys lack confidence, perform more attention-seeking behaviors, and are considered childish. Early maturation works against girls resulting in lowered self-concept, dissatisfaction with physical development, sexual precociousness, and increased potential for drug and alcohol use. Late maturing girls also are likely to be dissatisfied with their physical appearance and resent being treated as younger than they are. Factors making for good development are high socioeconomic status, a two-parent family, little visible disfiguration, and healthy parental adjustment.