The excellent Jonah Lehrer points to a recent study in the journal Intelligence, which examines some aspects of the "Flynn effect". The Flynn Effect is the tag to describe the observed general increase in the IQ of populations over the past few decades. There are several different as to why IQ scores are seeing such an increase, ranging from improved nutrition and medical care to less lead paint. To an extent, some of these hypotheses have been validated, the poorest students catch up to their peers.
But the study Lehrer focuses on also points to an increase of general IQ on the right hand side of the bell curve at about the same rate as the rest of the curve. This is a surprise based on the standard models, which suggest that improved nutrition, etc. should benefit those on the left side of the bell curve more than the right hand side.
These findings were measured by comparing 7th grade results on the SAT & ACT over the years, as well as 5th and 6th grade results on the EXPLORE test between the years of 1981 and 2000. The authors took stock of their results and noted that:
Rowe and Rodgers (2002) noted that “If the rising mean were driven by the smart getting smarter, then the change might reflect the introduction of some qualitatively novel form of environmental stimulation. If the overall distribution increased in pace, the cause would lie in processes that affected everyone equally.” We find the rising mean of the entire distribution is partly driven by the smart getting smarter. This suggests some form of environmental stimulation may be at work in the right tail.
In other words, the authors suggest that there must be something about our modern environment that is making everyone improve their IQ scores, not just certain groups. The question is: what is it?
A More Intelligent Culture?
Lehrer suggests that one culprit for this increase in intelligence may have something to do with living in a more intellectually complex society.
The question, of course, is what this stimulation might consist of? It obviously has to be extremely widespread, since the IQ gains exist at the population level. One frequently cited factor is the increasing complexity of entertainment, which might enhance abstract problem solving skills. (As Flynn himself noted, “The very fact that children are better and better at IQ test problems logically entails that they have learned at least that kind of problem-solving skill better, and it must have been learned somewhere.”) This suggests that, because people are now forced to make sense of Lost or the Harry Potter series or World of Warcraft, they’re also better able to handle hard logic puzzles. (The effect is probably indirect, with the difficult forms of culture enhancing working memory and the allocation of attention.) As Steven Johnson argued, everything bad is good for us, especially when the bad stuff has lots of minor characters and subplots. HBO is a cognitive workout.
I don't think this is a very likely explanation even as an indirect result. In fact, one could argue that causation could go the other way (smarter people leads to smarter culture). But I don't think there's a very strong relationship. Sure, it's true that a lot of TV is getting more complex, but I'd argue that that has more to with technology. Before the DVR, it was in the network's interest to make TV shows much more episodic, with a return to the status quo being the name of the game by the end of an episode or maybe a 2 or 3 part story arc. That kept audiences to a maximum, since you could drop in on a random episode and be able to follow along.
But in the age of the Internet, the explosion of original cable programming, the DVR, and season-long DVDs, network incentives have changed. Now it's better to promote active fan bases who respond better to serialization because it gives them more to talk about on the internet between shows, and makes them more likely to buy DVD box sets. And it's not like serialization is new - it was common in books and comic books for the same economic reasons of building up a fan base who'd keep coming back for more. Just ask Charles Dickens.
Moreover, it's not like popular entertainment generally has been increasing in complexity in any kind of linear fashion. Some of the most enduring works in the Western canon, such as Beowulf, the Iliad, and the Epic of Gilgamesh were complex, epic poems that took hours to recite - and people sat around and listened to them. Imagine the mindset it took to follow what happened in a story that you've been listening to for a few hours - that's what I call a cognitive workout! And let's not forget that Shakespeare's plays were written for -- and popular with -- "Joseph Six-Mug" who was looking for some time to kill. People have always hungered for complex stories.
The Problem With IQ Studies
Lehrer's hypothesis, although it sounds good (and I do appreciate the higher quality of TV these days), goes to an issue I have with IQ studies in general. Allow me to put on my IQ Skeptic Hat for a moment. [Full disclosure: I do not have an IQ Skeptic Hat - it's just a figure of speech. But I would totally wear one.] I am always skeptical about IQ studies or claims about general intelligence. I am skeptical because such reports are very amenable to confirmation bias. Take, for example, the news that spread like wildfire over the weekend that Internet Explorer users had lower IQs than users of other browsers. I saw that study, noted the red flags (like, for example, taking an online IQ test seriously), and dismissed it. Sure enough, it was a big fat hoax. But it was a hoax that fed into the biases of a lot of tech reporters, so it got less skepticism. You see this sort of thing come around every once in awhile. Sometimes about liberals and conservatives. Or different fans of different sports. That kind of thing. It's flattering to see yourself as "smarter than the other guy." So you have to be very careful when you evaluate this type of study.
Additionally, I have to say that I'm skeptical of the use of IQ as a measure of general intelligence, although I think it's a pretty valuable measure of many important cognitive skills. (I'd encourage you to read David Shenk's The Genius In All of Us if you haven't - it informs a great deal of my thinking about intelligence.) It's a measurement of certain cognitive skills, but I'm firmly in the camp that doesn't see it as an overall measure of general intelligence. But with this study in particular, we don't have to go that far. IQ tests are not what the authors used here. They used ACT, SAT, and EXPLORE scores. And those are not IQ scores. The purpose of those tests isn't to measure general intelligence - it's to predict which students are most likely to succeed in college. To be sure, there have been studies showing a correlation between SAT scores and IQ test scores (r=0.82), but it's not a correlation so high that there isn't some wiggle room in there.
A More Straightforward Interpretation: Getting to Carnegie Hall
But let's go with the benefit of the doubt and say that yes, SAT/ACT and EXPLORE scores can be can be used as an analogues for IQ and general intelligence. What does it mean that the scores are going up over time, across quartiles, including the brightest students, among 5th, 6th, and 7th graders? My alternate interpretation of the data is that this has less to to with kids getting smarter, and more to do with what Malcolm Gladwell identified in his book Outliers - people excel at things because they practice them for a long time. And what have we seen as a trend since 1981? The increasing use of standardized tests in schools. As far as I've been able to tell, standardized test use in schools has increased since the 1960s and that use continues to grow apace. I'd suggest that as standardized tests are used more in schools, students get better at grappling with the critical thinking aspect of those tests. Therefore, they perform better, thus increasing the scores over time as more and more students take more and more tests.
There's even a way to test this hypothesis, too: the dataset in this paper ends in 2000. If I'm right, then I'd expect the trend of increased scores to continue, and possibly even accelerate, in the years from 2001 - 2011. I say possibly even accelerate because since 2003, the No Child Left Behind Act has been in place, and the NCLB puts a greater emphasis on standardized test scores as a metric for school performance. The combination of more standardized tests, more standardized test practice, and more pressure to excel at standardized tests would, I'm guessing, lead to a continual increase probable accelerated increase of standardized test scores by students.
Now, my interpretation may be off, and it may well be that generalized intelligence is truly on the rise. But in the meantime, I'd suggest that the hypothesis of "more practice taking standardized tests leads to better performance on standardized tests" is a simpler fit for the data than "everyone's just getting smarter for some unknown reason." That answer doesn't quite satisfy the ego as well as "modern people are smarter, so take that, Isaac Newton!," but I think it's a likelier explanation.