<p>I've been reading a lot of different theories about how intelligence develops over childhood and adolescence, and I'm wondering about one specific aspect of it: The change or stability of the <strong>correlations between different intelligence domains over time</strong>.</p>
<p>Obviously, there's a ton of discussion on which intelligence domains exist (and, uh, what intelligence in general is supposed to be). But for this question, let's assume the five &quot;domains&quot; are the ones in the WISC-V because it's a common measure of intelligence in children: verbal comprehension, working memory, processing speed, fluid reasoning, visuo-spatial abilities. Let's also assume I am talking about the age period of around 6 years until mid-twenties. Finally, let's assume that we know that the domains are all intercorrelated (some pairs of domains more strongly than others) at every age.</p>
<p>Here are some wild and definitely not literature-based hypotheses:</p>
<ol>
<li><strong>The correlations don't change at all.</strong> There is a common factor to all of the domains that is relatively stable, and so is the level of their intercorrelations over childhood.</li>
<li><strong>The correlations grow stronger</strong> with age because of mutual benefits and better networks among all domains. The mutual benefits get stronger with age because more time means more interaction/closer networks and thus we get stronger correlations.</li>
<li><strong>The correlations grow weaker</strong> with age because the neural structures underlying the intelligence domains get more specialized by pruning and higher efficiency, which makes them more efficient and more independent. This leads to weaker correlations over time.</li>
<li>Inspired by Arnon Weinberg's comment: Because the environmental effect on general intelligence (&quot;g&quot;) gets smaller over childhood and plateaus around 18, the correlations between intelligence domains also grow weaker over childhood because the influence of the environment as a common factor to all of them sinks.</li>
</ol>
<p>Which hypothesis or which other theory is plausible, and is there actual research supporting it?</p>

CC BY-SA 4.0
2022-03-14T18:31:46.957Z
This is likely a question about "[psychometric g](https://psycnet.apa.org/record/2002-02875-003)" (also called g-factor): "... it reflects only the variance that all the different tests measure in common."  A potential answer comes from [the Wilson effect](https://doi.org/10.1017/thg.2013.54): "... the heritability of IQ reaches an asymptote at about 0.80 at 18–20 years of age ... shared environmental influence decreases across age, approximating about 0.10 at 18–20 years of age and continuing at that level into adulthood."
Arnon Weinberg
CC BY-SA 4.0
2022-03-14T21:38:09.170Z
@ArnonWeinberg Interesting, thank you! But my problem here is the opaque nature of g that has little to do with IQ-subtests. If we define g like Jensen - the shared variance of all subtests (which ones, though? depends on the test...), the Wilson effect doesn't necessarily apply because this effect is about IQ, which is an aggregate/average of subtest scores and not the same as their shared variance. Also, the effect is about correlations between twin's IQs over time, but my question is about the correlations in IQ subtests in single individuals over time.
louise
CC BY-SA 4.0
2022-03-15T03:50:38.670Z
Yes, agreed - hence only a potential answer: It suggests that rather than the generalization/specialization dichotomy presented in the question, the driving factor may be a reduced effect of environment over time.
Arnon Weinberg
CC BY-SA 4.0
2022-03-15T08:23:52.010Z
@ArnonWeinberg Ahh, I see, thanks! I'm not sure in which direction the reduced influence of environment would impact the correlations between the intelligence domains, but now I see that it could have an impact. My wild guess would be that correlations between domains get smaller when the environment's effect gets smaller, because it's a shared effect on all of them.
louise
<cognitive-psychology><intelligence><developmental-psychology><cognitive-development>
Are correlations between intelligence domains expected to increase or decrease over childhood and adolescence?
louise
# Are correlations between intelligence domains expected to increase or decrease over childhood and adolescence?

(Asked by: username_0 on 2022-03-14)

I've been reading a lot of different theories about how intelligence develops over childhood and adolescence, and I'm wondering about one specific aspect of it: The change or stability of the **correlations between different intelligence domains over time**.

Obviously, there's a ton of discussion on which intelligence domains exist (and, uh, what intelligence in general is supposed to be). But for this question, let's assume the five "domains" are the ones in the WISC-V because it's a common measure of intelligence in children: verbal comprehension, working memory, processing speed, fluid reasoning, visuo-spatial abilities. Let's also assume I am talking about the age period of around 6 years until mid-twenties. Finally, let's assume that we know that the domains are all intercorrelated (some pairs of domains more strongly than others) at every age.

Here are some wild and definitely not literature-based hypotheses:

1. **The correlations don't change at all.** There is a common factor to all of the domains that is relatively stable, and so is the level of their intercorrelations over childhood.
2. **The correlations grow stronger** with age because of mutual benefits and better networks among all domains. The mutual benefits get stronger with age because more time means more interaction/closer networks and thus we get stronger correlations.
3. **The correlations grow weaker** with age because the neural structures underlying the intelligence domains get more specialized by pruning and higher efficiency, which makes them more efficient and more independent. This leads to weaker correlations over time.
4. Inspired by username_1's comment: Because the environmental effect on general intelligence ("g") gets smaller over childhood and plateaus around 18, the correlations between intelligence domains also grow weaker over childhood because the influence of the environment as a common factor to all of them sinks.

Which hypothesis or which other theory is plausible, and is there actual research supporting it?

**Tags:** cognitive-psychology, intelligence, developmental-psychology, cognitive-development

> **Comments:**
> **username_1**: This is likely a question about "[psychometric g](https://psycnet.apa.org/record/2002-02875-003)" (also called g-factor): "... it reflects only the variance that all the different tests measure in common."  A potential answer comes from [the Wilson effect](https://doi.org/10.1017/thg.2013.54): "... the heritability of IQ reaches an asymptote at about 0.80 at 18–20 years of age ... shared environmental influence decreases across age, approximating about 0.10 at 18–20 years of age and continuing at that level into adulthood."  
> **username_0**: @ArnonWeinberg Interesting, thank you! But my problem here is the opaque nature of g that has little to do with IQ-subtests. If we define g like Jensen - the shared variance of all subtests (which ones, though? depends on the test...), the Wilson effect doesn't necessarily apply because this effect is about IQ, which is an aggregate/average of subtest scores and not the same as their shared variance. Also, the effect is about correlations between twin's IQs over time, but my question is about the correlations in IQ subtests in single individuals over time.  
> **username_1**: Yes, agreed - hence only a potential answer: It suggests that rather than the generalization/specialization dichotomy presented in the question, the driving factor may be a reduced effect of environment over time.  
> **username_0**: @ArnonWeinberg Ahh, I see, thanks! I'm not sure in which direction the reduced influence of environment would impact the correlations between the intelligence domains, but now I see that it could have an impact. My wild guess would be that correlations between domains get smaller when the environment's effect gets smaller, because it's a shared effect on all of them.  

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## 0 answers

