It also means that in many ways, you need not try to disentangle what your child brings in the way of intellectual capabilities from what you provide her with. All things considered, these are likely to be of a piece. There are some dramatic exceptions— children who might have tested very highly on Fagan's test of infant speed of processing but who grow up without fundamental resources such as adequate nutrition or regular attendance at a reasonable school are likely to seem less intelligent than they otherwise would. After a while, if you seem less intelligent, you are less intelligent. IQ is not simply a capacity; it is a pathway. Each step leads you farther in one direction and away from another. The child who feels smart seeks out stimulating aspects of the environment. The child who feels that others don't think he's smart begins to inhibit his performance, further lowering other people's expectations, and so on.
I have said a lot about the stability of a child's intelligence. But I have said little about how a parent knows whether his child is smart or not. After all, as I mentioned earlier, many, if not most, children seem smart to their parents, and few people have their child's IQ tested, nor should they. It rarely helps. If your child is very bright, the chances are that you and his teachers already know it. Getting a number can only send you into a tizzy of needless enrichment activities, pushing teachers in ways that don't help, or aggravating your friends by finding subtle ways to tell them how high your child's IQ is. If your child's IQ score is lower than yours, or than most kids', you might unwittingly transmit that information to your child. And as we have seen, lowered expectations usually only make matters worse. For most kids, most of the time, IQ tests aren't necessary. You usually can tell if a child is smart, if you know what to pay attention to. Children who learn new information easily, can solve problems, can create objects and ideas, and can understand complex situations are smart. Children who struggle with more than one of these challenges are less smart.
The one caveat to this is when a child is having trouble in school and you want to know whether it is because she has a learning disability. IQ scores, handled properly, can sort out the difference between a problem learning to read and a general intellectual deficit, which brings us back to Stevie.
Stevie took in information quickly, especially visual information. He could look at a structure and quickly build one just like it. He could watch someone put a toy together and quickly take over adding new parts himself. He could walk into a room and tell you, hours later, the color of the furniture or a picture that was hanging on the wall. When he wanted to make something, if he didn't have the right materials, he could find a substitute and finish his project. That is, he was quick to process information, he could solve problems, and he could fashion products valuable to his community. But this was only when he was interested in the problem he needed to solve or cared about the thing he was making.