Whether or not schooling can increase fluid intelligence is perhaps the most important research question – and instructional challenge – in the education sector.
The reason the question is so important is as follows:
(1) Increased IQ is connected to numerous positive outcomes.
(2) IQ is based on a combination of crystallized and fluid intelligence.
(2) We have evidence that schooling can increase crystalized knowledge.
(3) We have much less evidence that schooling can increase fluid knowledge.
(4) Figuring out how if / how we can increase fluid knowledge will be very important to continuing to raise IQs.
The benefits of increased IQ seem to be numerous.
As a recent post from the Atlantic noted:
IQ correlates with chances of landing a financially rewarding job. Other analyses suggest that each IQ point is worth hundreds of dollars in annual income—surely a painful formula for the 80 million Americans with an IQ of 90 or below… Studies have furthermore found that, compared with the intelligent, less intelligent people are more likely to suffer from some types of mental illness, become obese, develop heart disease, experience permanent brain damage from a traumatic injury, and end up in prison, where they are more likely than other inmates to be drawn to violence. They’re also likely to die sooner.
Garret Jones also covered what a nation’s collective of IQ can mean for well-being:
This is not to say that having a high IQ is necessary to lead a meaningful life; rather, it’s only to say that increases in IQ are at the very least correlated with positive outcomes, and this is especially true at the societal level.
Previous research indicates that it’s difficult to increase fluid intelligence through schooling.
For example, research on the best charter schools in the country point to the fact that it’s easier to achieve gains in crystalized knoweldge than it is for fluid knowledge:
Other research generally reflects this result: schools are more likely to deliver gains in crystallized rather than fluid knowledge.
With this context in my mind, I was excited to see Scott Alexander and Tyler Cowen blogging and tweeting about a new study from Sweden – a study that claims that an increase in years of schooling raised IQs for low-income / farmer families.
Here are the effects they found on IQ and EC (emotional control) for an additional year of schooling; the extension in schooling was rolled out across the country in phases which allowed for quasi-experimental analysis:
As you can see, the IQ effects are the largest for children of farmers and manual laborers.
Interestingly enough, the extra year of schooling reduced emotional control across most classes; the authors posit that this might be because education instills less emotional control than actually working, and that the rolling out of an additional grade might have stressed the educational system and negatively impacted school culture.
In detailing the IQ increases, however, the authors of the study do not directly comment on the whether or not the IQ gains were achieved through increases in crystallized or fluid intelligence.
They do describe the test used, but they are not clear about which sections tested which types of intelligence.
Intelligence was measured at conscription with four sub- tests: A) Instructions, 40 items measuring verbal ability (e.g. ‘strike the fourth number, put a ring around the se- cond’); B), Concept discrimination, 40 items measuring verbal and reasoning abilities in which the task is to choose the one of five concepts that does not belong; C) Paper form board, 25 items measuring visuospatial ability in which the task is to pick one of four sets of pieces that can form a given figure (a variation of the Minnesota Paper Form Board);35 and D) Technical comprehension, 52 items (a figure is shown and questions about a technical problem asked).
Given that it seems that the test covers some crystalized knowledge (technical comprehension – perhaps?), it’s difficult to say whether or not the gains in IQ reflect gains in fluid intelligence.
Without a clear break down of the score changes across various components of the intelligence test, the study is hard to interpret.
We already know that schooling can increase crystallized knowledge; if this is what actually happened here, then we’ve simply added to a robust body of exiting evidence.
We don’t know whether schooling can increase fluid knowledge; if this is what actually happened here, then it’s a pretty big deal.