We do not have strong evidence to support the existence of cognitive difference – Well-behaved women rarely make (scientific) history

Why are there fewer women scientists? People noticed the phenomenon behind the question and tried to give an answer. Some researchers related it to cognitive difference between men and women. True, they found some evidences for such difference. Yet none of the evidences is strong enough that can be accepted by entire scientific circle. In the first part, I will show that none of research results showing cognitive difference is stable, so cognitive difference cannot explain women’s underrepresentation in scientific fields. In the second part, I will try to give some reasonable explanations for the phenomenon.

The mainstream theories to support the existence of cognitive difference between male and female are relevant to brain and hormone. Most of the research results are not convincing, because they are either inconsistent, controversial, or without practical significance.

Studies about hormones are inconsistent. Many experiment results cannot be successfully replicated. For example, the hormone testosterone is believed to have positive correlation with spatial ability. Because the disease congenital adrenal hyperplasia (CAH) causes testosterone to be overproduced, researchers suppose that women with this disease should have higher score in spatial ability test. The results of the experiment are inconsistence. Former experiment with small sample got a significant result that women with the disease have higher spatial ability, but later research with larger sample size failed to find the same result.

The research about brain size is controversial. Some argue that men have bigger brain size than women, so men are more intelligent. The argument is unstable because brain occupies larger proportion in women’s body. Moreover, female’s neurons are packed more densely in some brain regions, so one can use the same data to establish an opposite argument: women are more intelligent that men because their neurons are denser in brain.

The research using intelligence test got many statistical significant results to show that men have high spatial ability and mental rotation ability. Though the data are statistical significant, the results have little practical value. Statistical significance does not mean practical value. Even tiny difference can be verified to be statistical significant. Today, doctors refuse to use new treatment only with statistical significance in experiment; they require the treatment effect are different enough from former one. Even meta-analysis of the spatial ability and mental rotation, the most acknowledged fields that favor men, shows effect size of only 0.13 and 0.56. The data are significant, but they do not have big practical value. The differences are fairly negligible compared to the same general intelligence of men and women.

Gender study is an independent subject today and belongs to scientific fields, so it is shocking that no consensus about cognitive difference exists. Gender study is interdisciplinary subject that combines biology, psychology, and social science. All other scientific subjects has some consensus as foundation, but for gender study, the existence of cognitive difference, is still controversial today. We have reason to believe that cognitive difference is too vague to have strong support.

Let’s get back to the original phenomenon that started the debate about cognitive difference: women’s underrepresentation in scientific fields. If the noun “cognitive difference” cannot give an explanation to this phenomenon, what is the answer? Well, we cannot partially give some environmental explanations without strong support. There are some broad acknowledged theories.

First, studies show that people tend to rate women lower than men when they have the same resumes, so women will have disadvantages in hiring process and promotion. Second, today’s academic system requires candidates to finish six years of Ph. D. stage right followed by six years of assistant professor stage to get a tenure position. The process gives big disadvantage to women because most women plan to give birth to children during this time period. But I have to acknowledge that these environmental based theories are just inference, either. Though some experiments have showed expected results to support these two theories, a large database is still unavailable. So we still cannot give a confident answer to the original question: why are there fewer women scientists.

Based on all the above, the existence of cognitive difference does not have strong support and cognitive difference cannot explain women’s underrepresentation in scientific fields. Some environmental based theories give us some reference. Scientists still need to do further research.

Reference:

Halpern, D. F. (2007). Science, Sex, and Good Sense: Why Women Are Underrepresented in Some Areas of Science and Math. American Psychological Association.

Hines, M. (2007). Do sex differences in cognition cause the shortage of women in science?.

Ying Wu says:

November 14, 2015 at 10:21 pm

Hi Amy, I really love your blog. You showed that the existing data and experiments could not show the cognitive difference between males and females. Good job and logic. I have the same opinion with you. I just want to add more examples about the point. As far as I am concerned, it is proper to doubt the interpretation about existing statistics about the cognitive difference. Many people use the tail ratio in Chapter 9 to interpret those data, which shows that the ratio of males to females at extremely high-ability levels strongly favors males. However, because of fewer women in science, there must have more males than females in science who are not at high-ability levels. So if we consider about the number but not the ratio, these tests actually favor females. Also, other seemly persuasive data such as SAT-M and IQ Score Band all have their own defects.