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  • Thomas Zoëga Ramsøy
    Home About Edge Features Edge Editions Press The Reality Club Third Culture Digerati Edge Search AN EDGE SPECIAL EVENT THE SCIENCE OF GENDER AND SCIENCE PINKER
    Message 1 of 1 , Jun 1, 2005
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      AN EDGE SPECIAL EVENT

      THE SCIENCE OF GENDER AND SCIENCE

      PINKER VS. SPELKE

      A DEBATE
      http://www.edge.org/3rd_culture/debate05/debate05_index.html

      [5.16.2005]

      ...on the research on mind, brain, and behavior that may be relevant to gender disparities in the sciences, including the studies of bias, discrimination and innate and acquired difference between the sexes.

      Harvard University • Mind/Brain/Behavior Initiative

      The Mind Brain and Behavior Inter-Faculty Initiative (MBB), under the leadership of Co-Directors Marc D. Hauser and Elizabeth Spelke, is a university-wide community that studies the structure, function, evolution, development, and pathology of the nervous system, in relation to decision-making and behavior.


      Introduction

      On April 22, 2005, Harvard University's Mind/Brain/Behavior Initiative (MBB) held a defining debate on the public discussion that began on January 16th with the public comments by Lawrence Summers, president of Harvard, on sex differences between men and women and how they may relate to the careers of women in science. The debate at MBB, "The Gender of Gender and Science" was "on the research on mind, brain, and behavior that may be relevant to gender disparities in the sciences, including the studies of bias, discrimination and innate and acquired difference between the sexes".

      It's interesting to note that since the controversy surrounding Summers' remarks began, there has been an astonishing absence of discussion of the relevant science...you won't find it in the hundreds and hundreds of articles in major newspapers; nor will find it in the Harvard faculty meetings where the president of the leading University in America was indicted for presenting controversial ideas.

      Scientists debate continually, and reality is the check. They may have egos as large as those possessed by the iconic figures of the academic humanities, but they handle their hubris in a very different way. They can be moved by arguments, because they work in an empirical world of facts, a world based on reality. There are no fixed, unalterable positions. They are both the creators and the critics of their shared enterprise. Ideas come from them and they also criticize one another's ideas.

      Through the process of creativity and criticism and debates, they decide which ideas get weeded out and which become part of the consensus that leads to the next level of discovery.

      But unlike just about anything else said about Summers' remarks, the debate, "The Science of Gender and Science", between Harvard psychology professors Steven Pinker and Elizabeth Spelke, focused on the relevant scientific literature. It was both interesting on facts but differing in interpretation.

      Both presented scientific evidence with the realization and understanding that there was nothing obvious about how the data was to be interpreted. Their sharp scientific debate informed rather than detracted. And it showed how a leading University can still fulfill its role of providing a forum for free and open discussion on controversial subjects in a fair-minded way. It also had the added benefit that the participants knew what they were talking about.

      Who won the debate? Make up your own mind. Watch the video, listen to the audio, read the text and check out the slide presentations.

      There's a lesson here: let's get it right and when we do we will adjust our attitudes. That's what science can do, and that's what Edge offers by presenting Pinker vs. Spelke to a wide public audience.

      —JB


      STEVEN PINKER is the Johnstone Family Professor in the Department of Psychology at Harvard University. His research has won prizes from the National Academy of Sciences and the Royal Institution of Great Britain, and he is the author of six books, including The Language Instinct, How the Mind Works, Words and Rules, and The Blank Slate.

      Steven Pinker's Edge Bio Page

      ELIZABETH S. SPELKE is Berkman Professor of Psychology at Harvard University, where she is Co-Director of the Mind, Brain, and Behavior Initiative. A member of the National Academy of Sciences and the American Academy of Arts and Sciences, she is cited by Time Magazine as one of America's Best in Science and Medicine.

      Elizabeth Spelke's Edge Bio Page



      THE SCIENCE OF GENDER AND SCIENCE
      PINKER VS. SPELKE
      A DEBATE

      [EDITOR'S NOTE: Pinker and Spelke each made presentations of about 40 minutes, without interruption, from each other or from the audience. They then responded to each other's presentations. By mutual agreement, Pinker made the first presentation.

      This Edge presentation includes: the transcribed text; streaming audio of the full debate; 6-minute video clips from Pinker and Spelke's opening statements; a 20-minute video clip of the their closing discussion; and online versions of the speakers' slide presentations. There are two options for viewing the slides: Clicking on the links immediately below brings up the file of either Pinker or Spelke's complete slide presentation. Or, the individual slides are also included for reference as expandable thumbnails in the margin of the transcript.]



      Steven Pinker
      [40 minutes]
      Streaming Audio

      Elizabeth Spelke
      [45 minutes]
      Streaming Audio

      Concluding Discussion
      [20 minutes]
      Streaming Audio

      Steven Pinker: Opening Remarks [6 minute video]
      Broadband | Modem

      Elizabeth Spelke: Opening Remarks [6 minute video]
      Broadband | Modem
         

      Steven Pinker & Elizabeth Spelke: Concluding Discussion [20 minute video]
      Broadband | Modem
         

      The complete video is also available for download through Harvard's MBB website (click here).

       



      Steven Pinker

         

      (STEVEN PINKER:) Thanks, Liz, for agreeing to this exchange. It's a privilege to be engaged in a conversation with Elizabeth Spelke. We go back a long way. We have been colleagues at MIT, where I helped attract her, and at Harvard, where she helped to attract me. With the rest of my field, I have enormous admiration for Elizabeth's brilliant contributions to our understanding of the origins of cognition. But we do find ourselves with different perspectives on a recent issue.

      For those of you who just arrived from Mars, there has been a certain amount of discussion here at Harvard on a particular datum, namely the under-representation of women among tenure-track faculty in elite universities in physical science, math, and engineering. Here are some recent numbers:

      As with many issues in psychology, there are three broad ways to explain this phenomenon. One can imagine an extreme "nature" position: that males but not females have the talents and temperaments necessary for science. Needless to say, only a madman could take that view. The extreme nature position has no serious proponents.

      There is an extreme "nurture" position: that males and females are biologically indistinguishable, and all relevant sex differences are products of socialization and bias.

      Then there are various intermediate positions: that the difference is explainable by some combination of biological differences in average temperaments and talents interacting with socialization and bias.

      Liz has embraced the extreme nurture position. There is an irony here, because in most discussions in cognitive science she and I are put in the same camp, namely the "innatists," when it comes to explaining the mind. But in this case Liz has said that there is "not a shred of evidence" for the biological factor, that "the evidence against there being an advantage for males in intrinsic aptitude is so overwhelming that it is hard for me to see how one can make a case at this point on the other side," and that "it seems to me as conclusive as any finding I know of in science."

      Well we certainly aren't seeing the stereotypical gender difference in confidence here! Now, I'm a controversial guy. I've taken many controversial positions over the years, and, as a member of Homo sapiens, I think I am right on all of them. But I don't think that in any of them I would say there is "not a shred of evidence" for the other side, even if I think that the evidence favors one side. I would not say that the other side "can't even make a case" for their position, even if I think that their case is not as good as the one I favor. And as for saying that a position is "as conclusive as any finding in science" — well, we're talking about social science here! This statement would imply that the extreme nurture position on gender differences is more conclusive than, say the evidence that the sun is at the center of the solar system, for the laws of thermodynamics, for the theory of evolution, for plate tectonics, and so on.

      These are extreme statements — especially in light of the fact that an enormous amount of research, summarized in these and many other literature reviews, in fact points to a very different conclusion. I'll quote from one of them, a book called Sex Differences in Cognitive Ability by Diane Halpern. She is a respected psychologist, recently elected as president of the American Psychological Association, and someone with no theoretical axe to grind. She does not subscribe to any particular theory, and has been a critic, for example, of evolutionary psychology. And here what she wrote in the preface to her book:


      "At the time I started writing this book it seemed clear to me that any between sex differences in thinking abilities were due to socialization practices, artifacts, and mistakes in the research. After reviewing a pile of journal articles that stood several feet high, and numerous books and book chapters that dwarfed the stack of journal articles, I changed my mind. The literature on sex differences in cognitive abilities is filled with inconsistent findings, contradictory theories, and emotional claims that are unsupported by the research. Yet despite all the noise in the data, clear and consistent messages could be heard. There are real and in some cases sizable sex differences with respect to some cognitive abilities. Socialization practices are undoubtedly important, but there is also good evidence that biological sex differences play a role in establishing and maintaining cognitive sex differences, a conclusion I wasn't prepared to make when I began reviewing the relevant literature."

      This captures my assessment perfectly.

      Again for the benefit of the Martians in this room: This isn't just any old issue in empirical psychology. There are obvious political colorings to it, and I want to begin with a confession of my own politics. I am a feminist. I believe that women have been oppressed, discriminated against, and harassed for thousands of years. I believe that the two waves of the feminist movement in the 20th century are among the proudest achievements of our species, and I am proud to have lived through one of them, including the effort to increase the representation of women in the sciences.

      But it is crucial to distinguish the moral proposition that people should not be discriminated against on account of their sex — which I take to be the core of feminism — and the empirical claim that males and females are biologically indistinguishable. They are not the same thing. Indeed, distinguishing them is essential to protecting the core of feminism. Anyone who takes an honest interest in science has to be prepared for the facts on a given issue to come out either way. And that makes it essential that we not hold the ideals of feminism hostage to the latest findings from the lab or field. Otherwise, if the findings come out as showing a sex difference, one would either have to say, "I guess sex discrimination wasn't so bad after all," or else furiously suppress or distort the findings so as to preserve the ideal. The truth cannot be sexist. Whatever the facts turn out to be, they should not be taken to compromise the core of feminism.

      Why study sex differences? Believe me, being the Bobby Riggs of cognitive science is not my idea of a good time. So should I care about them, especially since they are not the focus of my own research?

      First, differences between the sexes are part of the human condition. We all have a mother and a father. Most of us are attracted to members of the opposite sex, and the rest of us notice the difference from those who do. And we can't help but notice the sex of our children, friends, and our colleagues, in every aspect of life.

      Also, the topic of possible sex differences is of great scientific interest. Sex is a fundamental problem in biology, and sexual reproduction and sex differences go back a billion years. There's an interesting theory, which I won't have time to explain, which predicts that there should be an overall equal investment of organisms in their sons and daughters; neither sex is predicted to be superior or inferior across the board. There is also an elegant theory, namely Bob Trivers' theory of differential parental investment, which makes highly specific predictions about when you should expect sex differences and what they should look like.



      The nature and source of sex differences are also of practical importance. Most of us agree that there are aspects of the world, including gender disparities, that we want to change. But if we want to change the world we must first understand it, and that includes understanding the sources of sex differences.

      Let's get back to the datum to be explained. In many ways this is an exotic phenomenon. It involves biologically unprepared talents and temperaments: evolution certainly did not shape any part of the mind to do the work of a professor of mechanical engineering at MIT, for example. The datum has nothing to do with basic cognitive processes, or with those we use in our everyday lives, in school, or even in most college courses, where indeed there are few sex differences.

      Also, we are talking about extremes of achievement. Most women are not qualified to be math professors at Harvard because most men aren't qualified to be math professors at Harvard. These are extremes in the population.

      And we're talking about a subset of fields. Women are no under-represented to nearly the same extent in all academic fields, and certainly not in all prestigious professions.

      Finally, we are talking about a statistical effect. This is such a crucial point that I have to discuss it in some detail.

      Women are nowhere near absent even from the field in which they are most under-represented. The explanations for sex differences must be statistical as well. And here is a touchstone for the entire discussion:

      These are two Gaussian or normal distributions; two bell curves. The X axis stands for any ability you want to measure. The Yaxis stands for the proportion of people having that ability. The overlapping curves are what you get whenever you compare the sexes on any measure in which they differ. In this example, if we say that this is the male curve and this is the female curve, the means may be different, but at any particular ability level there are always representatives of both genders.

      So right away a number of public statements that have been made last couple of months can be seen as red herrings, and should never have been made by anyone who understands the nature of statistical distributions. This includes the accusation that President Summers implied that "50% of the brightest minds in America do not have the right aptitude for science," that "women just can't cut it," and so on. These statements are statistically illiterate, and have nothing to do with the phenomena we are discussing.





      There are some important corollaries of having two overlapping normal distributions. One is that a normal distribution falls off according to the negative exponential of the square of the distance from the mean. That means that even when there is only a small difference in the means of two distributions, the more extreme a score, the greater the disparity there will be in the two kinds of individuals having such a score. That is, the ratios get more extreme as you go farther out along the tail. If we hold a magnifying glass to the tail of the distribution, we see that even though the distributions overlap in the bulk of the curves, when you get out to the extremes the difference between the two curves gets larger and larger.

      For example, it's obvious that distributions of height for men and women overlap: it's not the case that all men are taller than all women. But while at five foot ten there are thirty men for every woman, at six feet there are two thousand men for every woman. Now, sex differences in cognition tend not to be so extreme, but the statistical phenomenon is the same.



      A second important corollary is that tail ratios are affected by differences in variance. And biologists since Darwin have noted that for many traits and many species, males are the more variable gender. So even in cases where the mean for women and the mean for men are the same, the fact that men are more variable implies that the proportion of men would be higher at one tail, and also higher at the other. As it's sometimes summarized: more prodigies, more idiots.

      With these statistical points in mind, let me begin the substance of my presentation by connecting the political issue with the scientific one. Economists who study patterns of discrimination have long argued (generally to no avail) that there is a crucial conceptual difference between difference and discrimination. A departure from a 50-50 sex ratio in any profession does not, by itself, imply that we are seeing discrimination, unless the interests and aptitudes of the two groups are equated. Let me illustrate the point with an example, involving myself.

      I work in a scientific field — the study of language acquisition in children — that is in fact dominated by women. Seventy-five percent of the members the main professional association are female, as are a majority of the keynote speakers at our main conference. I'm here to tell you that it's not because men like me have been discriminated against. I decided to study language development, as opposed to, say, mechanical engineering, for many reasons. The goal of designing a better automobile transmission does not turn me on as much as the goal of figuring out how kids acquire language. And I don't think I'd be as good at designing a transmission as I am in studying child language.

      Now, all we need to do to explain sex differences without invoking the discrimination or invidious sexist comparisons is to suppose that whatever traits I have that predispose me to choose (say) child language over (say) mechanical engineering are not exactly equally distributed statistically among men and women. For those of you out there — of either gender — who also are not mechanical engineers, you should understand what I'm talking about.

      Okay, so what are the similarities and differences between the sexes? There certainly are many similarities. Men and women show no differences in general intelligence or g — on average, they are exactly the same, right on the money. Also, when it comes to the basic categories of cognition — how we negotiate the world and live our lives; our concept of objects, of numbers, of people, of living things, and so on — there are no differences.

      Indeed, in cases where there are differences, there are as many instances in which women do slightly better than men as ones in which men do slightly better than women. For example, men are better at throwing, but women are more dexterous. Men are better at mentally rotating shapes; women are better at visual memory. Men are better at mathematical problem-solving; women are better at mathematical calculation. And so on.

      But there are at least six differences that are relevant to the datum we have been discussing. The literature on these differences is so enormous that I can only touch on a fraction of it. I'll restrict my discussion to a few examples in which there are enormous data sets, or there are meta-analyses that boil down a literature.

      The first difference, long noted by economists studying employment practices, is that men and women differ in what they state are their priorities in life. To sum it up: men, on average, are more likely to chase status at the expense of their families; women give a more balanced weighting. Once again: Think statistics! The finding is not that women value family and don't value status. It is not that men value status and don't value family. Nor does the finding imply that every last woman has the asymmetry that women show on average or that every last man has the asymmetry that men show on average. But in large data sets, on average, an asymmetry what you find.

      Just one example. In a famous long-term study of mathematically precocious youth, 1,975 youngsters were selected in 7th grade for being in the top 1% of ability in mathematics, and then followed up for more than two decades. These men and women are certainly equally talented.  And if anyone has ever been encouraged in math and science, these kids were. Both genders: they are equal in their levels of achievement, and they report being equally satisfied with the course of their lives. Nonetheless there are statistical differences in what they say is important to them. There are some things in life that the females rated higher than males, such as the ability to have a part-time career for a limited time in one's life; living close to parents and relatives; having a meaningful spiritual life; and having strong friendships. And there are some things in life that the males rated higher than the females. They include having lots of money; inventing or creating something; having a full-time career; and being successful in one's line of work. It's worth noting that studies of highly successful people find that single-mindedness and competitiveness are recurring traits in geniuses (of both sexes).

      Here is one other figure from this data set. As you might expect, this sample has a lot of people who like to work Herculean hours. Many people in this group say they would like to work 50, 60, even 70 hours a week. But there are also slight differences. At each one of these high numbers of hours there are slightly more men than women who want to work that much. That is, more men than women don't care about whether they have a life.

      Second, interest in people versus things and abstract rule systems. There is a staggering amount of data on this trait, because there is an entire field that studies people's vocational interests. I bet most of the people in this room have taken a vocational interest test at some point in their lives. And this field has documented that there are consistent differences in the kinds of activities that appeal to men and women in their ideal jobs. I'll just discuss one of them: the desire to work with people versus things. There is an enormous average difference between women and men in this dimension, about one standard deviation.

      And this difference in interests will tend to cause people to gravitate in slightly different directions in their choice of career. The occupation that fits best with the "people" end of the continuum is "director of a community services organization." The occupations that fit best with the "things" end are physicist, chemist, mathematician, computer programmer, and biologist.

      We see this consequence not only in the choice of whether to go into science, but also in the choice which branch of science the two sexes tend to go into. Needless to say, from 1970 to 2002 there was a huge increase in the percentage of university degrees awarded to women. But the percentage still differs dramatically across fields. Among the Ph.Ds awarded in 2001, for example, in education 65% of the doctorates went to women; in the social sciences, 54%; in the life sciences, 47%; in the physical sciences, 26%; in engineering, 17%. This is completely predictable from the difference in interests between people and living things, on the one hand, and inanimate objects, on the other. And the pattern is pretty much the same in 1980 and 2001, despite the change in absolute numbers.



      Third, risk. Men are by far the more reckless sex. In a large meta-analysis involving 150 studies and 100,000 participants, in 14 out of 16 categories of risk-taking, men were over-represented. The two sexes were equally represented in the other two categories, one of which was smoking, for obvious reasons. And two of the largest sex differences were in "intellectual risk taking" and "participation in a risky experiment." We see this sex difference in everyday life, in particular, in the following category: the Darwin Awards, "commemorating those individuals who ensure the long-term survival of our species by removing themselves from the gene pool in a sublimely idiotic fashion." Virtually all — perhaps all — of the winners are men.



      Fourth, three-dimensional mental transformations: the ability to determine whether the drawings in each of these pairs the same 3-dimensional shape. Again I'll appeal to a meta-analysis, this one containing 286 data sets and 100,000 subjects. The authors conclude, "we have specified a number of tests that show highly significant sex differences that are stable across age, at least after puberty, and have not decreased in recent years." Now, as I mentioned, for some kinds of spatial ability, the advantage goes to women, but in "mental rotation,"spatial perception," and "spatial visualization" the advantage goes to men.



      Now, does this have any relevance to scientific achievement? We don't know for sure, but there's some reason to think that it does. In psychometric studies, three-dimensional spatial visualization is correlated with mathematical problem-solving. And mental manipulation of objects in three dimensions figures prominently in the memoirs and introspections of most creative physicists and chemists, including Faraday, Maxwell, Tesla, Kéekulé, and Lawrence, all of whom claim to have hit upon their discoveries by dynamic visual imagery and only later set them down in equations. A typical introspection is the following: "The cyclical entities which seem to serve as elements in my thought are certain signs and more or less clear images which can be voluntarily reproduced and combined. This combinatory play seems to be the essential feature in productive thought before there is any connection with logical construction in words or other kinds of signs." The quote comes from this fairly well-known physicist.







      Fifth, mathematical reasoning. Girls and women get better school grades in mathematics and pretty much everything else these days. And women are better at mathematical calculation. But consistently, men score better on mathematical word problems and on tests of mathematical reasoning, at least statistically. Again, here is a meta analysis, with 254 data sets and 3 million subjects. It shows no significant difference in childhood; this is a difference that emerges around puberty, like many secondary sexual characteristics. But there are sizable differences in adolescence and adulthood, especially in high-end samples. Here is an example of the average SAT mathematical scores, showing a 40-point difference in favor of men that's pretty much consistent from 1972 to 1997. In the Study of Mathematically Precocious Youth (in which 7th graders were given the SAT, which of course ordinarily is administered only to older, college-bound kids), the ratio of those scoring over 700 is 2.8 to 1 male to female. (Admittedly, and interestingly, that's down from 25 years ago, when the ratio was 13-to1, and perhaps we can discuss some of the reasons.) At the 760 cutoff, the ratio nowadays is 7 males to 1 female.

      Now why is there a discrepancy with grades? Do SATs and other tests of mathematical reasoning aptitude underpredict grades, or do grades overpredict high-end aptitude? At the Radical Forum Liz was completely explicit in which side she takes, saying that "the tests are no good," unquote. But if the tests are really so useless, why does every major graduate program in science still use them — including the very departments at Harvard and MIT in which Liz and I have selected our own graduate students?

      I think the reason is that school grades are affected by homework and by the ability to solve the kinds of problems that have already been presented in lecture and textbooks. Whereas the aptitude tests are designed to test the application of mathematical knowledge to unfamiliar problems. And this, of course, is closer to the way that math is used in actually doing math and science.

      Indeed, contrary to Liz, and the popular opinion of many intellectuals, the tests are surprisingly good. There is an enormous amount of data on the predictive power of the SAT. For example, people in science careers overwhelmingly scored in 90th percentile in the SAT or GRE math test. And the tests predict earnings, occupational choice, doctoral degrees, the prestige of one's degree, the probability of having a tenure-track position, and the number

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