Malcolm Gladwell's article/book review on IQ in the New Yorker is a good read for anyone who wishes to brush up on the subject of the measurement of intelligence. Gladwell draws heavily from the work of James Flynn, who has a new book out called What is Intelligence?
Flynn gained a name for himself when he showed that IQ scores have risen over time throughout the world. The so-called Flynn Effect now receives mention in nearly all introductory psychology textbooks. You'll have to read his book to discover why he thinks IQ scores have risen over time. I wonder how much of the rising scores have to do with people taking the test (which rarely changes) repeatedly.
Gladwell and Flynn's discussion of intelligence raises some key topics and points worthy of debate. One of the most heavily debated is the influence of genetics and environment on intelligence. Another concerns to what extent the measurement of intelligence is actually the measurement of how well a person understands the cultural norms of the test creator. Finally, how should intelligence tests be used? These are the same questions I have my students think about during our unit on intelligence in introductory psychology.
My own stance on these topics is largely irrelevant when it comes to how I present the research on intelligence. At least, I try my best to make sure students get unbiased presentations of the issues, are armed with the research, and can state their own position on these three topics and back it up with a well-reasoned argument that relies on research. It's one of my favorite units in case you couldn't tell!
In any case, my position is that intelligence is influenced by both genetics and environment. I tend to look at the effect of environment as analogous to the effect of sunlight and soil condition on how well a plant grows to its potential height. Given impoverished sunlight and soil, plants are stumpy and leaves are small. However, given the right level of sunlight and soil nutrients for the plant, the plant grows taller and the leaves are broader. Sunlight and soil conditions are analogous to the availability of cognitively stimulating games, puzzles, and play as well as the absence of genetically based anomalies (such as an extra 21st chromosome) and environmentally induced brain damage such as from exposure to lead based paint and pollutants, blunt head trauma, oxygen deprivation, etc.
I also think tests that are culturally unbiased (at least less biased than the WISC and WAIS are) can be used to identify students who need special educational attention - whether they be students who score on the low or high end of the IQ spectrum. That is how intelligence tests were intended to be used by the original inventor of them - Alfred Binet. He wanted a standard, systematic way to identify struggling students who needed additional education. Although his test was itself extremely culturally biased, he had benign intentions. The Raven Standard Progressive Matrices are a relatively unbiased measure of nonverbal intelligence.
For a thorough and thoughtful discussion of the history and uses of intelligence tests, I highly recommend the book, The Mismeasure of Man by Stephen Jay Gould. It is *really* good.