Monday, April 23, 2012

Brains are like jelly....and they're fluid, too.

Intelligence is malleable?
Two pieces in the April 22 New York Times Sunday Magazine suggest that the idea that intelligence is fixed at birth has been greatly exaggerated.  We can get smarter if we work at it.  According to one piece, we have to exercise our fluid intelligence, and in the other, we have to exercise our bodies.

Fluid intelligence lifting weights
In 2008, two psychologists, Susanne Jaeggi and Martin Buschkuehl, published a paper in which they reported that young adults who play a challenging game requiring concentration can improve their "fluid intelligence", which the NYT article defines as "the capacity to solve novel problems, to learn, to reason, to see connections and to get to the bottom of things."
Psychologists have long regarded intelligence as coming in two flavors: crystallized intelligence, the treasure trove of stored-up information and how-to knowledge (the sort of thing tested on “Jeopardy!” or put to use when you ride a bicycle); and fluid intelligence. Crystallized intelligence grows as you age; fluid intelligence has long been known to peak in early adulthood, around college age, and then to decline gradually. And unlike physical conditioning, which can transform 98-pound weaklings into hunks, fluid intelligence has always been considered impervious to training.
The inflexibility of fluid intelligence has been the explanation for why we can't do better on I.Q. tests over our lifetimes.  Though, the pesky little problem of the Flynn effect, the sustained increase in I.Q. scores over decades in much of the world, has been a thorn in the side of those who hold that I.Q. is fixed.  And, even if people have never actually settled on what intelligence actually is, the idea that at least we know it's fixed, and that most studies show a considerable amount of heritability, has lead many to believe there must basically be due to the genotypes we're each born with.

Raven Matrix component of IQ test: fill in the blank square
Wikimedia Commons
So, if Jaeggi and Buschkuehl are correct that fluid intelligence can be improved with practice, a result they continue to demonstrate, this is a challenge to the idea that we're blessed or cursed with innate intelligence.  The idea is that intelligence must be similar to other highly heritable traits, like height, which is also susceptible to environmental effects -- even if within each individual's genetic or other constraints.

Mice lifting weights
The second intelligence story in the Sunday magazine comes at the issue from a different angle.  Mice given the chance to exercise get smarter.  Researchers determined this by giving them before and after cognitive tests, as well as before and after assessments of the structure of their brains.  And, as it happens, people who exercise get smarter, too.  Or at least their brains don't shrink nearly as much as they age as do the brains of sedentary people.
For more than a decade, neuroscientists and physiologists have been gathering evidence of the beneficial relationship between exercise and brainpower. But the newest findings make it clear that this isn’t just a relationship; it is the relationship. Using sophisticated technologies to examine the workings of individual neurons — and the makeup of brain matter itself — scientists in just the past few months have discovered that exercise appears to build a brain that resists physical shrinkage and enhance cognitive flexibility. Exercise, the latest neuroscience suggests, does more to bolster thinking than thinking does.
So, forget personalized genomic medicine, to get smart, just bike (or run) to work, thinking about something profound all the way.

Can this really be true?
Of course, Jaeggi and Buschkuehl have their critics.  Some simply don't believe that fluid intelligence is mutable, and studies continue to confirm this view. But J and B aren't the only psychologists who are beginning to find mutability and as a result, other psychologists are starting to believe their work. But, it's an interesting thing when expert assessment of scientific results depends on belief.  And the word is laced throughout the NYT piece.

Indeed, you're more likely to buy their work if you're not predisposed to think that I.Q. is genetically determined.  Well, and if you think I.Q. is real, measurable, not culturally determined and so on.  And where you come down on these issues seems to be correlated with your politics, at least to some extent.  Rather like where you come down on climate change, or evolution, or the genetics of how people vote.

But let's step away from the politics for the moment, and think about what our particular view of evolution might have to offer here.  Specifically, the idea that seems fairly obvious, that evolution has been consistently good at producing adaptability.  Over and over and over again, so much so that it seems to us to be a fundamental principle of life, organisms have been imbued with the ability to detect, evaluate, and adapt to changing circumstances.  So, to us, it's no surprise that our brains, too, can respond to changing circumstances, can respond to environmental challenges by, say, building new neuronal synapses.  It would be more surprising if it couldn't.  And changes in the brain can involve non-cognitive as well as cognitive intelligence -- that is, it need not involve consciousness as it often does in humans and presumably other animals.

Brains and central nervous systems are, after all, centers of evaluation.  Sensory inputs go there, and are sorted through and evaluated, and decisions made on how to respond to them.  The idea, no pun intended, is that the brain is not a pre-programmed, hard-wired automoton, but allows each unique moment to be sifted and judged, and even more, each moment can leave its mark.  Someone whose cognition is too rigid might be much more likely to be a former someone.

Brains have the texture of jello, but they're fluid as well -- food for thought at least.


Holly Dunsworth said...

Here's where I see part of the conundrum. There is nothing else on par with the complexity of intelligence or IQ to compare it with. How can we possibly understand the evolutionary significance of its heritability measures and its plasticity if there's nothing to stack it up against?

Ken Weiss said...

This comment would require a post (or series of posts) to answer, even if I understand the question. First, heritability is just a ratio of variation due to the effects of genetic variation alone, divided by the total variation. So it tells you nothing about how genes work just the rough fraction of all the observed variation in some data set (from some population) that is at play, relative to environmental factors.

The problems with heritability are first of all defining a trait that's biologically appropriate and appropriately measurable. That's where some of the controversy enters: is visual perceptive ability part of 'intelligence'? Or is IQ some quirky measure of brain function?

The heritability is about how whatever genetic mechanisms' variation is at play, relative to that behavioral measure. It really has nothing to do with its evolution--except that if it's only partly heritable or weakly 'genetic', that could mean that past adaptive selection was not very stringent relative to the inflow of new muations that affect the trait and the screening selection applied to variation.

But if the brain is an organ for collecting information and evaluating it, and IQ is about that evaluation ability, it would indicate that we shouldn't expect to find genetically hard-wired function. This has nothing to do, per se, with IQ but the degree to which specific behavior is genetically predetermined.

Other species have brains and hence IQ, though that would have to be measured on the species' own terms (since they don't have 'language' or 'writing' to measure it by). But why couldn't we test the plasticity of any species' typical behavior to understand how the evaluative and response ability works and varies?

With a trait that is about complex information gathering and evaluation, whose main characteristic is not to be predetermined, we obviously have to do a lot of speculation if we want to understand how 'it'--whatever 'it' is--evolved.

This may be why a lot of people seem to have a hard time understanding a trait that has evolved to be open rather than prescribed by genes. We tend to seek prescriptive genetic causation, as much easier to explain in, say biochemical or molecular terms. Whether that makes some scientists more open-minded and others closed-minded is another question.