Wednesday, February 08, 2006

Christmas Books: 1

Finding presents for friends and relatives is often a problem, made harder by the economist's puzzle of why one should give presents instead of giving cash and letting the recipient, better informed about his own preferences, decide how to spend it. A possible answer is that although I know less about the recipient, I know more about the gift. Acting on that principle, I occasionally pick a book that I and my wife particularly liked, buy a bunch of copies, and give them out as Christmas presents.

It occurred to me that some readers of this blog might be interested in hearing about them.

The Nurture Assumption by Judith Harris:

The author argues that while children are shaped by both genetics and environment, the relevant environment for most of them is not the home but the peer group. By her account, none of the popular stories about birth order, child rearing practices, and the like as determinants of adult personality are supported by the evidence. Human beings are good at recognizing that different rules apply in different environments. The typical child can and does show one face to his parents, a different one to his peers–and it is the peer group version that grows into the adult personality.

If she is right–and I think it likely that she is–that raises an interesting question about the history of psychology. How could beliefs about things such as the influence of birth order and childrearing be widely held within a scientific community when there was no evidence they were true?

Part of the answer is the confusion between genetic and environmental causation. Someone confident that personality depends only on environment will interpret similarities between parent and child as due to the affect of the environment provided by the parent. To distinguish between the two alternatives you need to look at children reared by people other than their biological parents. When you do so, it turns out that the observed similarities are in large part due to genetics.

Another part of the answer has to do with the nature of statistical evidence. Suppose you believe that birth order affects personality. You get personality evidence on a bunch of people, test for correlations between personality and birth order, and find one. First born daughters are (say) more self-confident than second and third born. You come up with a plausible explanation–the eldest child has had the experience of bossing her younger siblings around–and publish. The correlation is confirmed at the .05 level, meaning that there is no more than one chance in twenty that it could be due to chance.

Another believer in the importance of birth order does a similar study. He finds no effect for first born daughters, but discovers that last born sons are more optimistic than first born. He too comes up with a plausible explanation and publishes.

The process continues for many years. Occasionally someone is unable to find a correlation–and, since failure is rarely interesting, abandons that project in favor of something more likely to get published. Looking at the literature, it is obvious that birth order affects personality–practically everyone agrees about that–even if the details are a matter of dispute.

Only when it occurs to someone to combine the results from many studies does it become clear what is happening. With considerably more than twenty possible relations between birth order and personality, pure chance will usually result in a significant correlation for one of them–a different one each time. Pool the data and the result vanishes.

The origin of Harris's book makes an interesting story. It started as an article published in The Psychological Review. The article provoked a lot of mail–partly about the controversial argument, partly asking who the author was, since nobody in the field had ever heard of her.

Judith Harris had gotten a masters in psychology from Harvard and been discouraged from going further by a professor who assured her that she did not have the makings of a successful scholar. She left academia, married, and helped support her family by coauthoring child development textbooks. Eventually she concluded that a good deal of what those textbooks said was not supported by the evidence. The result was the article–which received the journal's prize for the year's best.

The prize is named after the Harvard professor who told her that she had no future as an academic. God, Judith Harris concluded, has a sense of humor.

15 Comments:

At 1:59 PM, February 08, 2006, Blogger Todd Mitchell said...

David, thanks for the heads up on the book. As a nurture proponent, it's nice to see "our side" getting some love these days.

 
At 3:51 PM, February 08, 2006, Blogger Mark Steckbeck said...

But it is also the case that parents have tremendous influence in deciding who their kids hang around with. Some of the influence is direct, but most is indirect. I'm sure that your method of parenting, the schools YOU decide your child attends, etc. influence the type of person he or she becomes by influencing with whom he or she hangs around.

 
At 4:02 PM, February 08, 2006, Blogger Patri Friedman said...

Todd - do you realize that the book argues that almost all the conventional beliefs about nurture mattering are wrong? Part of the basic thesis is that other than effects on your child's peer group, very little of parental nurturing matters (as long as you don't do a terrible job). I wouldn't exactly call it love for nurture...

 
At 4:39 PM, February 08, 2006, Anonymous Tom Courtney said...

"But it is also the case that parents have tremendous influence in deciding who their kids hang around with."

Some parents do, many do not. If you can choose 1 250 person private school, or home school your child with other like-minded parents, you will have some influence over their choice of peers. If you're sending your child to a 2500 person public school, you don't.

Even in the former case, the parents control isn't so great. It's all well and good if the kid chooses the peers you've set him up with, but if he chooses his World Of Warcraft buddies, or the blogosphere he's found, or the kids who hang out at the basketball court, then the parents' influence may not amount to so much.

 
At 4:50 PM, February 08, 2006, Anonymous Rue Des Quatre Vents said...

I read Harris' book after reading about it in Pinker's Blank Slate. I am no authority, but I found her arguments persuasive and exciting. But here's the intersting part, perhaps, of my post. Any time I explain Harris' thesis to people, they heap scorn on me, grow indignant, call me a nut and so on. Why is the reaction so strong? Is it because we live in a time when parents have the burden to produce paragons of virtue and intelligence? The other criticism comes from people who believe they made choices in their life and that these choices have great symbolic value for them. So it's wrong for me to belittle it. The choice I'm thinking of, for instance, belongs to the son of Japanese immigrants who grew indignant because he believes he chose to speak like an american and adopt american culture against his parents wishes. Rather than, as Harris proposes, because he has an inclination to conform to the language and culture of his peers. What are your thoughts on this indignation?

 
At 8:48 PM, February 08, 2006, Blogger Patri Friedman said...

I think part of what is going on is that parents really want their kids to grow up great, and so they really want to feel as though they have a role in making that happen. It's no fun to have something you care a great deal about be mostly out of your control. Since there are lots of things parents can do that feel like they should work, they do them and convince themselves that they do work. And of course, books and products cater to this urge.

The end result is that parents get invested in the idea, and don't want to hear that they wasted their time/money and don't actually deserve the credit for their kids turning out well.

 
At 9:27 PM, February 08, 2006, Anonymous Bryan Eastin said...

I am not a parent and never plan to be, so I feel I am pretty impartial. From personal experience, I would be shocked if parents don't have a tremendous influence on their children. I know mine had a lot of influence on me.

As far as the birth order thing goes, I offer an anecdote.

I went to Caltech for undergrad, which is a competitive tech school in Pasadena, CA. Once, on the way back from a community service event, a group of perhaps sixteen students and two staff stopped for dinner. Somebody brought up the question of birth order, so called off around the table. The results:
Firstborn staff: 0/2
Firstborn students: 15/16

I suspect if you ask Caltech for statistics you'll find that their excess of first born children is very statistically significant.

I know they keep such statistics. I could find out if anyone's really interested.

 
At 6:19 AM, February 09, 2006, Anonymous Julius Blumfeld said...

I think any parent would know that their child's fundamental personality traits are not a product of upbringing. But there are plenty of other important characteristics and virtues that parents surely play an important role in inculcating. To take an obvious example, some children are badly behaved little yobs; others are well mannered and courteous. I find it hard to believe that parents do not play a crucial role in such things.

And of course, parents are crucially responsible for whether their children have happy childhoods - something of great value in itsef.

 
At 8:57 AM, February 09, 2006, Blogger Todd Mitchell said...

Patri Friedman writes: "do you realize that the book argues that almost all the conventional beliefs about nurture mattering are wrong? Part of the basic thesis is that other than effects on your child's peer group, very little of parental nurturing matters..."

Parental nurturing, perhaps, but the peer group is also considered to be a nurturing or "socialization agent" (along with family, schooling, and the mass media). The effect of social interaction (be it with your family or peers or whomever) is more important in determining how a child develops than *genes*. That seems to still be more a nurture argument than nature.

 
At 10:23 AM, February 09, 2006, Blogger David Friedman said...

"The effect of social interaction (be it with your family or peers or whomever) is more important in determining how a child develops than *genes*."

That might be true, but it isn't the book's claim. She offers evidence that there are both genetic and environmental influences. Her point is not about their relative size--it's that the environmental ones are primarily from the peer group not the family.

 
At 3:30 PM, February 09, 2006, Blogger Andy said...

Finding presents for friends and relatives is often a problem, made harder by the economist's puzzle of why one should give presents instead of giving cash and letting the recipient, better informed about his own preferences, decide how to spend it.

I've had some of my own thoughts on how to solve this problem.

Read them here:
http://dhyb.blogspot.com/
2005_12_01_dhyb_archive.html#113525570410408034

 
At 2:29 AM, February 10, 2006, Blogger Gustavo Lacerda said...

Judith Harris sounds like a excellent example of independent scholarship.

How did she support herself during this time? How did she maintain contact with the academic community?

Are there funding opportunities for people who want an alternative to the standard academic path?

 
At 10:13 AM, February 10, 2006, Blogger David Friedman said...

Gustavo Lacerda asks:

"How did she support herself during this time? How did she maintain contact with the academic community?"

She was married, so I assume partly supported by her husband. She supplemented the family income by coauthoring child development textbooks. My impression is that she didn't have much personal contact with the academic world, but was keeping up with the literature.

 
At 8:17 PM, February 12, 2006, Anonymous R.L. said...

Occasionally someone is unable to find a correlation–and, since failure is rarely interesting, abandons that project in favor of something more likely to get published. Looking at the literature, it is obvious that birth order affects personality–practically everyone agrees about that–even if the details are a matter of dispute.

I wonder if something like this might apply to the literature (or at least the soundbytes that get quoted) in issues such as global warming, second-hand smoke, and cell phone use.

Re cell phone use, the figure "4 times as risky" comes up a lot, but the actual factors measured in different studies seem to contradict each other.

One study, Redelmeier's, found a correlation between accidents and calls that were completed as long as 14 minutes before the accident, with an explanation that the person would still be thinking about whatever had been talked about.

Others talk about attention being used to interpret voice social signals during the call -- hardly likely to be going on 14 minutes later.

Some tests report 'impairment' when the subject cannot later describe billboards or other roadside distractions; but roadside distractions, which do draw eyes away from the road, are a large cause of accidents, so drawing attention from them might be a net gain.

 
At 4:39 PM, April 10, 2010, Anonymous Anonymous said...

If birth order is so important, how then could anyone assess it's influence on me?

I was in turn, an only child, the youngest child, the middle child, and the oldest child.

I was an only child until my parents adopted a boy older than me. He died at age 17. They then adopted a 3 year old, which technically made me a middle child. Plus they briefly kept two of my older brother's sisters, both younger than me.

What is my birth order? I've had a taste of all three possibilities and understand the pressures and frustrations of all three. This I can affirmed: being the oldest is the best deal; although being the youngest had it advantages in that I had an older brother to take up for me and ease the way at school.

 

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