Newborn babies are busier than they look. Their bodies run on reflexes, movements a baby makes without choosing to. Doctors check a newborn's reflexes to see whether the brain and nervous system are working well.

Take the grasp reflex. When you stroke a newborn's palm, the fingers close around yours. It lasts until a baby is about 5 to 6 months old, and then it fades away.

Then there is feeding. When a baby's cheek is touched, the baby turns toward the touch and opens the mouth. This is the rooting reflex, and it helps the baby find food. Sources give about 4 to 6 months for when it fades. A hand-to-mouth reflex goes with rooting and sucking, so babies may suck on their fingers or hands. The sucking reflex does not start until about the 32nd week of pregnancy.

Two more reflexes involve the whole body. A loud sound or a sudden move can make a baby stretch out the arms and legs and then pull them back in. A baby's own cry can even set off this startle reflex.

Vision develops alongside the reflexes. A newborn's eyes focus best on things about 8 to 12 inches (20 to 30 centimeters) away, about as far as a parent's face. Newborns like to look at faces and at black-and-white or high-contrast patterns. For the first two months, the eyes are not well coordinated and may seem to wander or look crossed, which is usually normal. By about 2 months many babies watch people as they move. Seeing takes both the eyes and the brain. Signals travel from the eye to the brain, and a baby's brain has to learn to use what the eyes send.

Crying is a message system. Babies cry to tell the people near them what they need, such as food, a hug, a clean diaper or sleep. They cry more in their first 3 months than at any other time, and crying usually gets better after that. A baby's first signs of communication come when the baby learns that a cry brings food, comfort and company. A familiar, gentle voice can calm a crying baby.

Babies are also learning language long before they speak. They can hear loud sounds from the start, and newborns begin to recognize important sounds, such as the voice of a caregiver. By 6 months most recognize the basic sounds of the language around them, and by the end of the first year they have learned a great deal about its sound structure. Learning language is more than making sounds. Listening, understanding and knowing the names of people and things are all part of it.

Sound-making follows a path. Up to about 4 months, babies coo with soft pleasure sounds like oooo and aahh. Babbling, strings of sounds like tata, upup and bibibi, starts in the first year of life. Scientists call the back-and-forth between a baby and a caring grown-up serve and return, like a game of tennis. When an adult answers a babble, gesture or cry with eye contact, words or a hug, the baby's brain builds and strengthens connections. In the first few years of life, the brain grows new connections at a very fast rate.

Bodies catch up with the brain. At first a baby's head flops backward if it is not supported, and by 2 months many can lift it when lying on the tummy. Around 6 months many babies roll from tummy to back, push up on straight arms, and lean on their hands to sit with support. They reach out to grab a toy they want. Between about 9 months and a year, babies pull themselves up to stand and may crawl.

Around their first birthday, many babies say one or two simple words, such as hi, dog, Dada or Mama. But they understood words long before that. Babies learn words like cup and shoe, and they respond to simple requests, before they say them. In the second half of the first year they enjoy peek-a-boo, and by around 12 months they find hidden objects easily.

Words to know

• reflex: unchosen move
• rooting: finding food
• startle: sudden jump
• babbling: strings of sounds
• coordinated: working together