By 3 months of age, infants can bring their hands to the midline (in front of their face). This promotes several benefits: they can easily get their fingers, thumb, and often fist into their mouth enabling them to suck on these body parts and thus promote self-calming skills (vs. having to rely on their parents). In addition, the ability to reach out with their hands and tactilely interact with their environment leads to much excitement. During this period it is important for infants to experience "tummy time" - (i.e., placement on the tummy). This position promotes utilization of back and neck muscles. For infants with flattening of their head due to positioning restrictions of lying on the back, the prone position will also help alleviate this cosmetic issue.