Gifted Issues Discussion homepage Forums GT Research The Nature and Nurture of High IQ

http://pss.sagepub.com/content/early/2013/07/01/0956797612473119.abstract

The Nature and Nurture of High IQ
An Extended Sensitive Period for Intellectual Development
by Angela M. Brant et al.
Psychological Science
July 1, 2013

Abstract
IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.

Here's a recent thread where Zen Scanner posted links about parts of gifties brains developing later than average.
http://giftedissues.davidsongifted....2403/Interesting_article_about_ADHD.html


I think there's something to it. When I was younger I always explained myself as "ageless", describing while I now know is called asynchronisity. Whenever asynchronisity comes up online I like to explain that I don't see it as being stagnated levels, but more like the range of development is wider, both older and younger at the same time.... not like one area's older and and another area's younger, more like many areas are both older and younger at the same time.

Thanks for the research link. Be interesting to see the full study at some point. I like seeing research scaffolding, where the more expensive and thus limited sample size of the cortical thickness study helps inform a larger scope study like this.

Cortical changes continue well into the early 20's, and this has certainly been known for quite some time. It's a range, naturally-- a bell curve, if you will.

So for the population as a whole, where is "maturity" then? Is it 18 yo? 20? 21? Well, legally, it's generally considered 21 in North America. But historically, it's often been considered 25 or even 30-- especially for men.

Actuarial science doesn't lie, let's just say, and there's a darned good reason why rental car agreements specify an age which is far greater than "adulthood" in the legal sense. My recollections are that this is based largely on the actuarial results which indicate that the 95% confidence interval surrounding "good judgment" for complex tasks which require fully-developed executive regulation (like driving a car) is about 25 years of age. Auto insurers don't really consider anyone a "good driver" before then, but they are starting to tweak things to reflect a more nuanced view-- on the basis of OTHER accomplishments that tend to indicate conscientiousness, good self-control, etc.

Access to the principal of trust funds is also quite frequently set at "mid-20's" and this has been true for at least two centuries.

Anyway-- all of that to say that this particular avenue of research definitely seems to agree strongly with empirical observations over many, many decades. While some people may 'mature' ahead of those expectations, it's also likely that many mature behind the average, too.


How cool would it be if PG kids could finally be recognized as having unique vulnerabilities and needs in an educational sense-- all by virtue of this particular "delay" in brain development??

Personally, I would like to see the voting age upped to 25...

The article posted by the OP also provides me with some insight into why so many of my school reports contained comments about my immaturity - LOL

Different people have different arcs of development over a lifetime.

Yes-- it's a distribution. Presumably, level of development at any particular age should be a Gaussian distribution...

but maybe that is just an assumption, too. Maybe it's NOT a Gaussian distribution at all. I love to see studies that examine those assumptions.

Okay. Well. I got the study. Oh dear.

They compared people with "high IQs" to others. They didn't actually define "high IQ." But they did write the following:



This means they cut out any IQ score above 124. So they wanted IQ scores that were high but not too high.

When I couple this with the fact that they didn't provide a range or even an average for their high IQ category, I feel dubious. If they removed people with IQs at least ~1.5 SD above average and then didn't define "high IQ" in the ones who remained, how can anyone draw conclusions about their claims? Any interpretation of high IQ here is arbitrary, beyond the fact that in this study it was, at best, "above average."

PM me if you want a copy of the paper.

Hi Val, thanks so much for the peek inside. Wow, what a disappointment. With that many data points, statistics is designed to manage the impact of those outliers, unless... unless those data points completely undermine the hypothesis. Then excluding them would be...?

I'd love a copy, Val. I have no doubt that differences in rate and timing of brain develop play roles in psychiatric disorders and adult brain functioning but I wondered if the high IQ subjects were also in more enriched environments than the low IQ subjects, and if that could partially explain differences in brain development between the groups.