The Cognitive Development of an Infant

Birth to Three Months

• In the first three months of life, a baby is busy developing its sensory and motor skills; it understands almost nothing about its environment, except that some things feel nice and other things feel uncomfortable. However, by the end of the third month your baby might have started smiling on purpose, recognizing familiar people and objects and imitating your facial expressions.

Four to Six Months

• During this time your baby's memory and attention span are increasing, and he is starting to distinguish different sounds in speech. He'll start recognizing his own name. He may become fascinated with mirrors and start responding to other people's facial expressions. Notably, he might start attempting to reach for objects that are beyond his grasp.

Seven to Nine Months

• If your baby hasn't already done so, at this stage she'll start responding to her name and being able to tell your emotions from your tone of voice. She'll start being able to find objects that are hidden.

10 to 12 months

• By the end of their first year, most babies fully understand that objects don't disappear when they go out of sight. Your baby knows that if you leave the room you are still nearby. She can understand simple commands and uses some words and exclamations like "no," "mama," and "uh oh." If you name an image she can correctly point to it, and she is starting to explore her environment in new ways, like throwing, dropping and shaking things. She'll also start understanding how to use household objects such as brushes, cups and the telephone receiver.

Range of Normal

• Not all babies develop cognitively at the same pace, and there is a large spectrum of "normal." If your baby has not reached important milestones at exactly the typical times, there is not necessarily any reason for alarm. Your doctor can help you evaluate when to worry and when to simply be patient.