It can be difficult to observe and measure an infant's cognitive development until he's about 3 months old, when he should begin responding to bright colors, lights, noisy rattles and human voices by turning toward them. Meal times highlight the daily agenda: He recognizes the breast or bottle and eagerly responds.
During the first 12 months, he's exploring. By the end of that time, he should have discovered several ways to investigate items, such as shaking, rolling, banging and throwing. (By now, you've probably learned to put all breakable items out of his reach.) These investigations should lead to preliminary competence, during which he starts to correctly use objects, such as a brush, a cup or a toy phone.
Around 2 years old, he should begin imaginative play and "make believe." Much of this play involves social situations. By 3, he should be aware that he and others think (also known as the theory of mind) [source: Price]. Jump to age 4, and he should have learned to count at least ten blocks, raisins or pennies. He should have a concept of time by age 5 (but that doesn't necessarily mean he'll hurry up or get ready quickly).
From about ages 6 to 8, he should be able to talk meaningfully about his feelings and ideas. (He may hold a real conversation about his favorite movie or explain why it's lousy that he got picked last for kickball.) Reading and mathematical skills tend to develop dramatically at this age. He also should be less egocentric. That doesn't necessarily mean he's been selfish, but just that he's literally more aware of others now.
More great cognitive leaps are pending:
- Later childhood (9 to 11): He can apply knowledge more readily to new situations.
- Early adolescence (12 to 14): Whether you want him to or not, he is capable of discussing his feelings more clearly -- often more loudly, and in detail.
- Middle adolescence (15 to 17): Everyday decision-making skills have improved, but that doesn't necessarily mean he'll put on a coat in cold weather. That's more related to social development.
That's what'll likely be going on inside his head for the first seventeen years. What will all this thinking prompt him to say? Up next, we'll take a look at language development.