Psychology Grows Up

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I would have been terrified to discuss Judith Rich Harris’ “The Nurture Assumption” when it was first published in 1998. Harris — not a researcher or professor, but a writer of psychology textbooks who had washed out of Harvard’s Ph.D. program many years before — was proposing a complete revision of the prevailing assumptions about childhood development. Her thesis, in a nutshell: “Parental nurturing is not what determines how a child turns out. Children are not socialized by their parents. The nurture assumption is a myth and most of the research used to support it is worthless” (xv). This was radical indeed. If Harris’ analysis was correct, almost all current child development theories could be thrown out the window. Discarded, as well, would be popular therapies such as psychoanalysis, and all theories which assume that children are largely blank slates on which their parents write their future character.

How was the poor layman supposed to handle this hot potato? Whom could you solicit for an unbiased opinion on this paradigm-shifting thesis? A Newsweek cover story on Harris (Sept. 7, 1998), while noting “some big guns on her side,” called that “a minority opinion,” and went on to say that “many scientists are nothing short of scathing” about her ideas; it quoted several of them. And the opposing scientists were, indeed, scathing. But you could hardly look for guidance from the putative experts, for in many cases these were the same people whose lifetime assumptions were under fire.

Harris did have early supporters. Harris’ article kicking off her revisionism, published in the prestigious Psychological Review in 1995, won the George A. Miller award for “an outstanding recent article in psychology” — a delicious irony, for the same George A. Miller after whom the award was named had signed the letter asking her to leave Harvard’s Ph.D. program. The review in The New York Times Book Review by social psychologist Carol Tavris was favorable, if somewhat cautious. And David Rowe, a behavioral geneticist who in 1994 had published “The Limits of Family Influence,” was an immediate ally.

But Harris’ detractors were heavily credentialed, and the unfavorable reviews numerous. The reader could certainly be sure that Harris wrote and analyzed well, but if you bought into her theory on the evidence of her book alone, there was always the possibility that she was ignoring a body of contradictory evidence, or misinterpreting the data in some subtle way. The possibilities for the layman — or even the expert, for that matter — to make a fool of himself seemed to lie on every side.

In 2008, when “The Nurture Assumption” was reissued in a 10th- anniversary edition, the picture was much less intimidating. That is not to say that Harris’ views had been wholeheartedly accepted. Far from it. But it had become clear that there was no hidden body of evidence, no glaring misinterpretation. It appears that her devastating critique of what she calls “the nurture assumption” has not been refuted, and further research has reinforced her conclusions. It seems unlikely that formerly mainstream views will recover completely from Harris’ razor-sharp analysis.

During the intervening decade, Harris had also published a follow-up, “No Two Alike” (2005). The reviews of this book were considerably friendlier, the criticisms more cautious. No more scathing comments — at least not that I could find. Harris was now part of the intellectual landscape; it was no longer possible to dismiss her out of hand, in hopes she would go away.

The believers in the central role of early childhood experience, and of parents, in determining personality — “developmentalists,” as Harris calls them — have defended their views with two main arguments.

Argument number one: “The interactions are so complex that we simply can’t separate parental influence from other factors.” Harris devotes a chapter of “No Two Alike” (27–49) to demonstrating how carefully designed studies can, indeed, tease out parental influence from other determinants.

Argument number two: “Parents have lots of influence, but in unpredictable directions, so that no net effect shows up in the studies.” This is theoretically possible, but Harris points out that this would mean that each given style of parenting would produce balanced effects, i.e. that “the same parental behaviors can cause one child to

While researching for yet another textbook, Harris noticed that mainstream assumptions did not fit with the findings of carefully designed studies.



become more cheerful and another more depressed, one more honest and the other more deceptive” (74). The likelihood of such balance seems quite low. And even if that were true, what would it say about the developmentalists’ proclivity for recommending some parenting styles over others? If the effects are evenly balanced, any such recommendations are baseless. The developmentalists, as Harris points out, want to have it both ways.

It may be that developmental- ists will eventually be able to salvage more than the 1% parental influence on a child’s eventual adult personality that Harris grants them in a generous moment. (Harris does note that a few studies reach the high-water mark of 5%, though she calls them “of dubious quality” [86].) But, in Harris’ wake, theories of parental influence on development will find it difficult to regain the hegemony they enjoyed through the latter half of the 20th century.

True, Harris’ theories about what shapes adult personality are themselves speculative, and like all new theories should be viewed with a healthy skepticism. But they are intriguing and well-reasoned, if only preliminary. We may ask those who pounce on the incompleteness of her attempts: who can expect the pioneer to find her way directly to the full truth, without misstep or deviation?

Harris is, first of all, an analyst and organizer of others’ research studies, and secondly, a theorist with an outsider’s perspective on the field of psychology. She has suffered from a hard-to-diagnose combination of the autoimmune diseases lupus and sclerosis since the 1970s, and lives a mostly shut-in life. During the years 1981–1994 she wrote textbooks on child development. These early books relied on both the research and the theories of others and reflected the mainstream emphasis on the central role of parents in childhood development. But while researching for yet another textbook, she noticed that these mainstream assumptions did not fit with the findings of a number of carefully designed studies.

Harris never completed the textbook. Instead she spent months delving ever more deeply into the research on development. She found that much of the research that supported the orthodoxy was undermined by a fundamental flaw: the failure to control for the effects of heredity. Many studies show, for example, that children of broken homes are more likely than other people to get divorces. Yet factor in the genetic component — inherited personality characteristics associated with divorce that are demonstrably not correlated

with shared experiences — control for socioeconomic status and an increase in parental changes of residence, and the connection, so often carelessly attributed to differences in the specific in-home environment, disappears. (“Nurture Assumption” 290–291.)

In taking note of the significant effects of genetics, and casting doubt on the more extreme claims of developmentalists, Harris was only repeating the conclusions of observant parents everywhere. (My own four children differed markedly in their response to stimulus while still in the womb, not to mention afterwards.) But the evidence, and Harris’ analysis, did far more than simply repeat, time after time, the importance of the genetic makeup of children. It also reduced to near-zero the role of differing upbringing styles or “psychologically correct” parental strategies in determining adult personality. (One reviewer joked that if Harris could have reduced it to less than zero, she would have.) Now that was not intuitive to any late-20th-century parent, caught up as we were in the culture of the Dr. Spock generation. But as Harris points out, the belief in dispositive parental influence is relatively recent: former generations assumed what now seems one half-step closer to the truth, that personality was inborn.

Astonishingly, it doesn’t seem to matter much whether identical twins are raised in the same family, or raised in different families; either way, they end up just as similar — and just as different. Much has been made of the bizarre similarities of identical twins raised in separate households, but Harris is equally impressed, and more interested, by the remarkable degree of difference between identical twins raised in the same household.

Harris is careful to point out the ways in which parents are important — especially in providing the basics for survival, such as food, shelter, and protection. It is only after these are controlled for as much as possible that we see parental influence approach zero. Prenatal environment is important. It is also crucial that parents, or parent substitutes, provide visual stimulation, exposure to language, and the opportunity for human attachment during the first three years of life; without these, normal development is endangered. In addition, parents’ socioeconomic status and their choice of where to live are crucially important in determining what their children’s peer group is likely to be; one of the few active steps parents can take to shape their children’s future, according to Harris, is to change neighborhoods. She also makes an exception for the rare — usually large — family, or more likely group of families (she cites the Amish and Orthodox Jews), that succeeds in creating its own mini-peer- group. Another exception: “Anything learned at home and kept at home — not scrutinized by the peer group — may be passed on from parents to their kids. Maybe even how to run a home” (“Nurture Assumption” 311). And there is of course a host of influences on a minor level — if you pay for enough piano lessons, your child will probably learn to play the piano.

This adds up to a lot of, well, what we laymen might call “nurturing.” But we must remind ourselves that Harris is using the phrase “the nurture assumption” to stand for a deep and elaborate array of child development theories popular during the latter half of the 20th century. The normal parental nurturing of young children, as practiced throughout the millennia, is not in question.

Then what is it that parents, with few exceptions, do not do? Harris’ evidence is strong that parents’ varying child-rearing styles or philosophies do not shape their children’s personalities, do not teach them strategies they use in dealing with the social world outside the family, and do not determine their future happiness.

Then what does shape personality? No one is sure. Clearly, heredity is important. The studies of behavioral geneticists indicate that inherited traits account for about 45% of adult personality (“No Two Alike” 119). It has been argued that they are overstating the case by failing to separate heredity’s direct effects from the environmental feedback of those same effects. Children with certain inborn traits will go on to be treated differently by both parents and peers, which will magnify the effects of the original genetic differences. So perhaps genetics directly determines only 30% of adult variation. But Harris can shrug her shoulders at this controversy, for her goal is to account for the 55% that lies outside both direct and indirect genetic determinants.

Then there’s the random factor — from the “developmental noise” that creates small genetic differences even between identical twins, to chance encounters with strangers on the street or bullies in the schoolyard. Though Harris gives a nod to randomness, she does not find it a complete or satisfying explanation. In “The Nurture Assumption,” she focuses on peers. She makes an excellent case that personality is still quite malleable well up into the teenage years, but that even in early childhood, outside-the-home behavior is influenced far more by peers than by parents. One telling example is that children of immigrant parents tend to resist speaking their parents’ language, instead becoming fluent, and accentless, in the language of their school-mates. Other examples abound.

Harris’ main goal in “The Nurture Assumption” is to debunk the titular premise, and to provide a plausible substitute for parental influence. In this she can be said to succeed. But peer influence provides that substitute largely for the lack of other possible candidates. Solid evidence is hard to come by. The studies Harris cites in support of her “group socialization theory” were not designed with her theory in mind; in fact, many are simply failed attempts to demonstrate the importance of the parental role.

It also remains unclear exactly who constitute “peers.” Do we include only the peers the child knows personally, or do perceived peers (known from television shows, commercials, magazine articles, and ads) also count? What drives children and teenagers to conform to their peers, and what makes them differ?

In “No Two Alike,” Harris addresses these questions, and more. She devotes the first part of the book to restating and redefending the main thesis of “The Nurture Assumption”; no need to have read her first book in order to read the second. Some may find this section repetitive, and her attack on a few of the critics of “The Nurture Assumption” has struck some readers as unnecessarily detailed, not to mention merciless, but Harris writes and thinks so well that I for one am happy to go along for the ride. We follow Harris as

she tracks down the unpublished study that the Newsweek cover story cites in its “Exhibit A,” and discovers that Newsweek has misreported a crucial fact. (The article states, “[ Jerome] Kagan measured babies at 4 months and at

Much of the research that supported the orthodoxy was undermined by a fundamental flaw: the failure to control for the effects of heredity.

school age.” It was really at 4 months and at 21 months.) And it is instructive, as well as humbling, to see Harris demonstrate how fatally flawed a plausible- seeming study can be.

I’m afraid I could easily have breezed through the summary of a study of “positive parenting” on school behavior, for example, and come away with the impression that the authors had indeed produced evidence of the benefits of improving school behavior through instructing parents in such parenting, as they apparently thought they had. It takes Harris’ scalpel to show that the authors had failed to control for what is known as “compliance determined susceptibility bias.” By selecting a subgroup of parents who were most willing to follow parenting advice, they allowed genetic factors to come into play; children of conscientious parents might well inherit the tendency to be conscientious themselves. Go back to randomly assigned groups — both of those instructed in “positive parenting” and of those given no instruction at all — and the positive effects disappear; no difference in school behavior was observable between the two groups (133–135).

In another example, Harris digs deep to find that one widely quoted (though never published) study seems to have been based on the interactions of fewer than eight rhesus monkeys, followed only to the age of 15 months. For various technical reasons, and because some of the monkeys had to have been used as controls, it seems highly likely that the conclusions were based on the reactions of one or two monkeys (64–68). The phrase “grasping at straws” comes to mind.

In the second part of the book Harris is bold enough to develop her own theory of childhood and adolescent development. In her view, adolescents of a given peer group are similar to one another because of the effects of an innate socialization system that creates the urge to conform to one’s peers. At the same time, they will differ because of another inborn desire: to achieve status within that same group of peers.

It is hardly innovative to point out the importance of status in human relations — status has been a theme of literature ever since Achilles chose glory

Freud failed to consider that it could be heredity that caused finicky mothers to have finicky children.



over long life in Homer’s “Iliad,” and it would be difficult to make a list of contemporary novels that do not deal with status. In Dale Carnegie’s popular book, “How to Win Friends and Influence People” (1936), I find this saying: “If you tell me how you get your feeling of importance, I’ll tell you what you are” (50).

But two things are, as far as I know, unique to Harris. One is her claim that it is precisely the striving for status that drives individuation. Even identical twins growing up in the same household find that they cannot occupy the exact same status niche; they must specialize in order to compete. The other is her careful delineation of the status system from two other “systems” or “modules” of the brain that deal with human interactions: the relationship system and the socialization system. She provides a useful chart of the three.

The idea that the brain has different, and sometimes conflicting, systems for dealing with its various tasks is consistent with research into damaged brains and of the findings of brain-scan technology — and consistent with the results of introspection as well. But it should be noted that, to date, there is no hard evidence for the existence of

the three separate systems that Harris proposes. It is not happenstance that she makes many references to famous fictional detectives (Doyle’s Sherlock Holmes, Sayers’ Peter Wimsey, and Tey’s Inspector Grant), for her method is similar: eliminate all other possible suspects, until only one is left standing. But just as in reading any detective novel, we have to ask ourselves: has our detective cast her web broadly enough, considered all the potential suspects?

In support of her theory she calls on the reasoning of evolutionary psychologists, and especially on one of their popularizers, the linguist (and follow- ing the publication of “The Nurture Assumption,” email friend of Harris) Steven Pinker. Now, I admire and recommend Pinker — you have to love a colleague of Noam Chomsky who is perfectly willing to praise, for example, the work of Thomas Sowell. But the disparity between the inflated claims printed on the cover of Pinker’s 1997 book — here I need only refer to the title, “How the Mind Works” — and the light, lively, fascinating, but sketchy and speculative work that lies between the bindings, illustrates the gap between reach and grasp in Pinker’s nascent field.

For the most part Harris’ anthropological speculations seem quite sound; it seems highly likely that early humans formed into groups and subgroups, and that children’s survival beyond the age of three had more to do with their membership in the group than with the efforts of their parents. I am fascinated by Harris’ casual speculation that, far from having an overpowering tendency to learn life lessons at home, the growing mind might not only resist generalizing from any one social context to another, but might specifically be structured to resist generalizing from family to outside-family milieus. One young person I know posited that the influence was more likely to go the other way from that suggested by the developmental psychologists: she finally learned how to deal with an overbearing father by adopting strategies she gained in dealing with other overbearing adults.

However, the reader may feel a certain disjunction between Harris’ meticulous care in the interpretation of experimental results and her much more speculative use of the “reverse engineering” of evolutionary psychology. Reverse engineering is great fun, and potentially illuminating, but it strikes me as a somewhat dicey business, based as it is on assumptions about the unknowable life of prehistoric hunter-gatherers. The common working assumption, that their life was much like that of existing (or recently exist- ing) hunter-gatherers, is questioned by many anthropologists, who note that surviving groups of hunter-gatherers are of necessity those who occupy remote and marginal territories, while prehistoric humans no doubt concentrated in relatively rich areas. There is some reason to think that late Paleolithic homo sapiens enjoyed a robust health, not equaled since. Australian anthropologist Peter McAllister maintains, for example, that aboriginal runners could have outsprinted Usain Bolt.

But this is a relatively minor quibble. It should come as no surprise that when analysis gives way to theory- building, the reasoning necessarily becomes looser and more speculative. And at our current level of understand- ing of the human mind, any proposed theory is necessarily sketchy.

So little is known! This is the most astonishing revelation of the “nurture assumption” controversy — that so much developmental theory could have been built on such weak foundations. When we read that Freud failed to consider that it could be heredity that caused finicky mothers to have finicky children, rather than, as he opined, the mothers’ toilet-training practices, we may feel indulgent about a pioneer’s mistakes. But when it is demonstrated that the same sort of mistake was repeated over and over during the next century, it is not indulgence we feel, but amazement and dismay. Here is one reason psychology has lagged behind the other sciences.

Think of the waste! Think of the hundreds of books that carefully instruct parents in the best way to craft their children’s development, from Dr. Spock’s fairly benign advice to extraordinarily perfectionist and guilt-inducing works such as “The Drama of the Gifted Child” (2008). The thousands of articles. The countless hours that patients have spent on the couches of psychoanalysts, attempting to clear neuroses that were either imaginary or activated only in the family context. Your love-hate relationship with your father or mother may be quite real, and can upset you every time you interact with or even think of him or her, but it may not be otherwise important in your life today. Cognitive, behavioral, and interpersonal therapists have long emphasized focusing on the neuroses of time now, with notable success; studies indicate that in the treatment of depression, for example, the benefits of their therapies often equal or surpass those of the popular antidepressant drugs. By contrast, traditional psychotherapy, with its focus on past trauma, is a signal failure in dealing with depression — on average, it has no favorable effect at all. In a sense, Harris’ work is a case of theory catching up with practice.

It will take both to clear away decades of intellectual rubble. And it will be a struggle. There is a strong paternalist streak among the intellectual elite — witness their influence within the Beltway. Established academicians and popular writers alike have resisted Harris’ conclusions not so much because they are untrue as because they are thought to be dangerous. What will parents make of the observation that parenting styles don’t seem to matter very much? Won’t they take that as an excuse to neglect or maltreat their children? Knowing parents, both good and bad, I doubt that the answer is yes. But paternalist assumptions run deep in our current welfarist, for-the-children society, motivating a great deal of behavior that we would be better off without.

In “The Nurture Assumption,” Harris provides a rather good “moral of the story” — a moral I wish she had emphasized more in her later book. Her suggestion is that parents would do best to focus on their relationship with their children in the present, rather than constantly strategizing their parental role, trying to push or prod or sculpt their children into what they conceive as the proper shape for the future. I think this is good advice, no matter what the percentage of parental influence turns out to be. Overbearing parenting — and we must remember to include in this general category the over-nurturing, overpraising, and over-sensitivity that has become popular today — isn’t a good idea, even for the parents. It isn’t that

children’s futures are thereby imperiled; it is simply that their presents are thereby degraded. Reflecting on the death of his son, the character of Alexander Herzen in the Tom Stoppard play “Shipwreck” says, “Because children grow up, we think a child’s purpose is to grow up. But a child’s purpose is to be a child.” We don’t have to be looking to the future to value a good relationship with our children. Harris emphasizes that the parent-child relationship is important in the same way that every long-term relationship is important. It is part of our lives.

Despite this life-affirming conclusion, Harris later found it necessary to write, in an article for the Wilson Quarterly (“How to Succeed in Childhood,” Winter 1999): “I am not advocating irresponsibility. Parents are in charge of how their children behave at home. They can decide where their children will grow up and, at least in the early years, who their peers will be. They are the chief determiners of whether their children’s life at home will be happy or miserable, and they have a moral obligation to keep it from being miserable. My theory does not grant people the license to treat children in a cruel or negligent way.” But I think it very unlikely that Harris’ theories will be taken as an excuse for cruelty or negligence; parents who wish to be cruel or negligent are not usually looking for intellectual excuses to do so. And though Harris probably means physical abuse when she refers to “cruelty,” it may be that the hectoring and guilt-tripping and bullying inflicted by many well-intentioned parents should count as a form of cruelty as well, and that the perpetrators, and their children, will greatly benefit from having the unnecessary — indeed, imaginary — burden of shaping children’s character removed from the parents’ shoulders.

At this point we can only dream of the day when someone might provide the same service to teachers and their pupils. “In loco parentis” still means responsibility to the state for “shaping young minds,” with all the attendant arrogance, cost, and sheer waste of time.

The cultural zeitgeist responds very slowly to new ideas, and the 20th century’s intellectual fads will no doubt take many decades to fade. Books and articles

of bogus parental advice are still being written, printed, and sold. The state, whether governed by Republicans or by Democrats, is more willing than ever to subsidize and insist upon the importance of “educating the whole child,” in an expert-approved way, both at home and in the classroom.

Luckily, Harris’ struggle with an entrenched establishment is not a lonely one. First of all, her work is based on the original research of many others. And, in a number of interrelated fields, there is a widespread effort to replace those academic subjects that carry the hitherto oxymoronic rubric, the “social sciences,” with something worthy of the name. Psychology may be in the forefront of this changeover. Yet it is still struggling to shrug off the pseudo-scientific heritage — indeed, one might almost call it the witch-doctory — of its beginnings, as it attempts to gain the status of a true science by incorporating the insights gained from genetics, neuroscience, and other “harder” disciplines (also, however, largely in their infancy). Asked whether psychology is finally on its way to becoming a true science, Harris responded: “I’m doing my best to nudge it in that direction. Its progress has been very uneven, with some specialties forging ahead and others lagging behind.”

This is part of the process of clearing away a widespread cultural myth — the myth of “the blank slate,” as Pinker calls it (the title of his 2002 book). Harris’

There is a strong paternalist streak among the intellectual elite — witness their influence within the beltway.



work is one part of the clearing process. She shows that it isn’t only laymen who should repeat to themselves 20 times each morning, “Correlation does not equal causation.” In attempting to go further, to point the way toward a new developmental theory — and pointing the way is all she really claims to do — she necessarily exposes herself to attack from the flank. But I believe she is pointing in the right direction.

It’s hard to know what effect the eventual fall of the blank-slate mythology will have on the cultural and political scene. Conservatives, who have long claimed that the utopianism of the left is based on the erroneous assumption that human nature is infinitely malleable, are understandably feeling vindicated. But any theory of personality can be bent to almost any political end. The assertion that there is such a thing as innate individual nature, or that individuals are, for better or worse, influenced by peer groups as well as by their parents, doesn’t have to constitute an endorsement of conservatism. You can find it in many a libertarian essay. As Harris commented in an email, “the fact that something is innate doesn’t mean that it’s unchangeable.”

Pinker closes a chapter of “The Blank Slate,” by saying: “Every student

of political science is taught that political ideologies are based on theories of human nature. Why must they be based on theories that are 300 years out of date?” (305). Though it will settle nothing, I would like to think that the quality of debate will be improved by the debunking of the “tabula rasa” myth.

In the grand scheme of life, however, how one votes in the general election is of vanishingly small significance. Far more important are one’s day-to-day interactions. Harris’ work can and should have an impact not only on every parent but on every child. And everyone is someone’s child. Harris largely avoids giving advice; hers are not self-help books. But surely an appreciation for the truth of the parent-child relationship will have a beneficial effect. Truth always turns out to have its uses.


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