However, it turns out that IQ tests (and many other measures of achievement) don't just measure innate intelligence, they also measure whether the person taking the test bothers to try hard enough to get it right. Paul Tough quotes some fascinating research along those lines in this except from his book How Children Succeed.
Consider a couple of experiments done decades ago involving IQ and M&M’s. In the first test, conducted in Northern California in the late 1960s, a researcher named Calvin Edlund selected 79 children between the ages of 5 and 7, all from “low-middle class and lower-class homes.” The children were randomly divided into an experimental group and a control group. First, they all took a standard version of the Stanford-Binet IQ test. Seven weeks later, they took a similar test, but this time the kids in the experimental group were given one M&M for each correct answer. On the first test, the two groups were evenly matched on IQ. On the second test, the IQ of the M&M group went up an average of 12 points—a huge leap.Another study, which tracked high school and college students over subsequent decades, and included a test which in effect measured the willingness of the taker to take the time to get easy but tedious questions right, found that this motivation to do well even on a seemingly low reward test was just about as good a predictor of success later in life as measured IQ.
A few years later, two researchers from the University of South Florida elaborated on Edlund’s experiment. This time, after the first, candy-less IQ test, they divided the children into three groups according to their scores on the first test. The high-IQ group had an average IQ score on the first test of about 119. The medium-IQ group averaged about 101, and the low-IQ group averaged about 79. On the second test, the researchers offered half the children in each IQ category an M&M for each right answer, just as Edlund had; the others in each group received no reward. The medium-IQ and high-IQ kids who got candy didn’t improve their scores at all on the second test. But the low-IQ children who were given M&M’s for each correct answer raised their IQ scores to about 97, almost erasing the gap with the medium-IQ group.
The M&M studies were a major blow to the conventional wisdom about intelligence, which held that IQ tests measured something real and permanent—something that couldn’t be changed drastically with a few candy-covered chocolates. They also raised an important and puzzling question about the supposedly low-IQ children: Did they actually have low IQs or not? Which number was the true measure of their intelligence: 79 or 97?
This is the kind of frustrating but tantalizing puzzle that teachers face on a regular basis, especially teachers in high-poverty schools. You’re convinced that your students are smarter than they appear, and you know that if they would only apply themselves, they would do much better. But how do you get them to apply themselves? Should you just give them M&M’s for every correct answer for the rest of their lives? That doesn’t seem like a very practical solution. And the reality is that for low-income middle-school students, there are already tremendous rewards for doing well on tests—not immediately and for each individual correct answer, but in the long term. If a student’s test scores and GPA through middle and high school reflect an applied IQ of 97 instead of 79, he is much more likely to graduate from high school and then college and then to get a good job—at which point he can buy as many bags of M&M’s as he wants.
But as every middle-school teacher knows, convincing students of that logic is a lot harder than it seems.
You would think this would be a hopeful sign: that many people who might otherwise appear to be destined to do poorly can do better if only they can be motivated to exert themselves. But as the article describes, attempts to motivate people (outside the confines of offering candy for answers on a fairly short test) are often surprisingly unsuccessful. There are already very strong incentives to try hard in school and in life, the problem is that the rewards are distant.