A Market Model of Human Personality 4: Five Brain Types

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Baron-Cohen pages on this site:
The Essential Difference (2003):

The Essential DifferenceSummaryCommentsClassismFive Brain Types

This page comments on Simon Baron-Cohen's recent book, The Essential Difference (2003), in particular, on the five human brain types he claims there are. The comments link back to the summary of the work, also on this site.

1 Essential differences

The book's title suggests that Baron-Cohen is going to reveal that there is one and only one key distinction of some sort between men and women. Also, some pages in, when he talks about 5 brain types, ranging from extreme male to extreme female, the reader will surely jump to the conclusion that the book is somehow going to be about some simple continuum that runs between the two extremes. Indeed, isn't that what an extreme is, one end of a simple continuum between polar opposites of some kind: cold and hot, short and tall and so on.

Baron-Cohen has introduced the empathy and systemising he is going to be talking about separately and pointed out that they are separate, associated with different areas of the brain. But it seems unlikely that this overrides the reader's impression of a single distinction.

A more accurate title for the book would have been The Essential Differences. [Back to Article]

2 The Balanced Brain

Like the extreme female brain discussed later, the balanced brain mentioned at the start of the book appears to be hypothetical. In spite of it apparently being an integral part of his theory, the author spends less than a page discussing it. On that page, he talks about it only in terms of if and might. Thus we find:

A different explanation of why we might find the balanced brain to be less common - and this needs proper testing ... [p 131]

We may note that none of the book's getting on for 600 references to learned sources appear to relate to the balanced brain. We may also note that Baron-Cohen does not offer an estimated percentage of the population who might have the balanced brain, the way he does for the hypothesised extreme female brain. [Back to Article]

3 Autism: The Extreme Male Brain

Autism: The Extreme Male Brain is the title of the book's 10th chapter. It seemingly suggests that the autism spectrum and Baron-Cohen's EMB are the same thing. What is more, the author says nothing to dispel this impression. In the 10th chapter, we are told that 1 in 200 children is on the autism spectrum, but we are given no statistic there for the incidence in the population of the extreme male brain.

However, it turns out that the two are by no means the same. For we eventually get the statistic for the EMB in the 12th and final chapter, though only incidentally, in the course of its initial discussion of the extreme female brain. It turns out that, according to the author, about 2.5% of people have the EMB. Of course, he has made things somewhat difficult for the average reader not only by placing the two statistics two chapters apart, but also by offering them in different formats.

Once alerted, we can work out that the 1 in 200 for the autism spectrum is 0.5% and 2.5% for the EMB is 1 in 40. So, the two are clearly far from the same, far from coextensive in the population. Put most simply, only 1 in 5 people with the EMB is going to be on the autism spectrum.

But the casual reader is not going to have spotted the issue and done the calculation.

The 2.5%

Again, Baron-Cohen does not explain where his figure of 2.5% actually comes from. Most importantly, he does not suggest that there is some kind of obvious threshold, making the difference between a person in his 2.5% easily distinguishable from anybody in the other 97.5%. The lay reader, for whom the book is obviously intended, is in most instances going to overlook the matter. But any that doesn't is left to surmise that 2.5% is a figure chosen on the basis of some convention of advanced statistics.

The point is really this. Baron-Cohen is meticulous enough to provide in the book approaching 600 references to over 450 learned sources, but he is unforthcoming in this matter of the basic statistic of EMB incidence in the population, when EMB is a central topic of the work: so central that it figures in the book's subtitle: Men, Women and the Extreme Male Brain. [Back to Article]

4 The Extreme Female Brain

It is hard to believe that 2.5% of the population have the extreme female brain but that it has not yet been detected. Assuming that most of the people with this type of brain are women, then we are talking about a condition that affects up to 5% of them, 1 in 20, but it hasn't been detected.

But even if we don't consider the sex of the alleged EFB 2.5%, it is difficult to understand that 1 in 40 of the population overall has one, but it hasn't been detected.

Note that although the EFB figures prominently in the title of the book's last chapter, The Extreme Female Brain: Back to the Future, it is the subject of only the first 4 of the chapter's 16 pages; the rest is the book's conclusion.

Note also that although the section on the EFB contains 4 pointers to learned references, these references are presumably not going to provide evidence of the existence of the EFB: otherwise Baron-Cohen would not be saying that it hasn't been detected yet.

EFB and the Empathy Quotient Questionnaire

It is interesting to reflect on the connection between (a) the inability as yet to identify EFB in actual people and (b) the existence and use of the Empathy Quotient Questionnaire reproduced in Appendix 2. On the one hand, Baron-Cohen uses the term hyperempathy in relation to EFB, so it seems as though a person with EFB would have a very high empathy quotient. On the other hand, the Empathy Quotient Questionnaire is presented as capable of detecting very high empathy quotients.

This capability of the Empathy Quotient Questionnaire for detecting very high empathy quotients is suggested by the rubric on interpreting the scores, where scores of 64 to the maximum of 80 are called very high.

But clearly, this cannot be the case, otherwise, actual people would surely have been detected by the questionnaire. After all, if it is conjectured that about 2.5% of the population, probably 5% of all women, has the condition, you should not have to do very much testing before you have a hit. Indeed, you'd be unlucky not to find an EFB person among your first 50 subjects.

We may note also that scores of 0 to 32 are called low and we are told that Asperger Syndrome people get around 20. We may suppose that if the author had something to tell us about the people getting very high scores, he would have done so.

What are we to make of this? Presumably, that even though the questionnaire is good at discriminating at the low end, delivering a range of quotients for AS people, who represent only 0.5% of the population overall, it is weak at the high end. For EFB conjecturally involves as much as 2.5% of the population, but the questionnaire cannot find them.

EFB and the Systemizing Quotient Questionnaire

Of course, Baron-Cohen's EFB is not just a matter of very high empathy, but also of low systemising. So if it is not possible to use the Empathy Quotient Questionnaire to identify EFB people, how about using the Systemizing Quotient Questionnaire instead, where a low score would indicate a subject with the EFB.

Well, this route to possible EFB identification must presumably have so far drawn a blank too, given that the condition has not yet been detected. What is more, the point about the discriminatory weakness of the empathy test at the high end of scores will apply at the low end for the systemising test. [Back to Article]


(c) John Durham, 2003 - 2004

Baron-Cohen pages on this site:
The Essential Difference (2003):

The Essential DifferenceSummaryCommentsClassismFive Brain Types