> Come on, Fab - pointing out examples of brain differences explaining > behavioral differences is hardly convincing evidence that brain > differences are the right explanation in this case.
My point is that behavior is more than cost-benefit calculations with IQ as an intervening variable. My purpose in citing this kind of evidence is that behavior depends on cognitive faculties which are dependent on well developed parts of the brain. Damasio's book shows some evidence that brain differences *might* lead to behavioral differences. I'm not an anatomist, but I wouldn't be surprised if children's brains simply didn't have all the parts developed for correctly learning social behavior. > Yes, there are cognitive abilities with low g-loading, and memory is > one. But now that I think about it, I shouldn't have let you get away > with citing memory differences in the first place. Children in fact > seem to have much *better* memorization ability than adults in numerous > respects. > Prof. Bryan Caplan It's well documented that long term memory is nil for children less than five years of age (doctors call it "pediatric amnesia") and is very spotty until about 12. Maybe children can remember strings of numbers well in labs, but they can't remember things from a year or two ago terribly well. And it's this long term learning that's needed for socialization. Social behavior draws from a large pool of past experience, not the short term memory tested in laboratories. (Do a real world test: ask a 7 year old about how they misbehaved two years ago. If you get anything remotely accurate, I'll buy you lunch.) Also, while were at it, I think you overinterpret the G-loading thing. A G-loading is essentially a factor analysis of responses to a standardized test. Statistically, you estimate a linear model. G -> response to Question 1 G -> ... Question 2, etc. G is often called a "latent factor" that is *unmeasured*. See any non-economics statistics book (economists rarely use this and it's not in Golderger, Amimiya or Greene). Then you can test alternative models like G1 -> Q1, Q2, Q4 G2 -> Q3, Q5, etc. and do model comparisons. IIUC, the psychometric literature has found that the first model has a really good fit while other models have poorer fits for tests of abstract thinking. What is this G? It's a *construct* from the test, not a direct measurement of anything. Which means to assert one single process called IQ is really strecthing it. What you can safely say is that G is the dimension along which test responses vary. This dimension can be the consequence of a bunch of other things and you can collect data to test hypotheses about these more complex models: F1, F2 --> G --> Q1, Q2, Q3. My whole point is that obsessing over G might lead one to ignore the stuff that leads to G. In a lot of these IQ/behavior debates people seems to take extreme positions that IQ is this all powerful explanatory device, or that it is meaningless when it's neither. I really think that some people are more intelligent than others and that this matters alot, but explaining everything in terms of G seems a bit dicey to me. Fabio