Brizendine: The Female Brain (2006)

This is a bio-fundamentalist tract insisting that all gender issues can be explained in terms of hormones and brain wiring.

It's got a bunch of references, but they are given in unmarked endnotes which refer, in turn, to a bibliography. This means that it's quite hard to find reference that's supposed to back any specific claim.

So what I want to do here is to make the connection explicit. I'll go through a little snippet of the text, pointing out directly where the information comes from. I've also looked at the underlying texts, and perhaps not surprisingly, it often turns out that Brizendine often refers to things that are irrelevant or have opposite conclusions of what she is claiming.

The part of the text that I focus on comes from chapter six, "Emotion: The Feeling Brain." I include only quotes from the three first subsections,"The Biology of Gut Feelings,""Getting Through to the Male Brain," and "When He Doesn't Respond the Way She Wants Him To." This corresponds to pages 117–126 in the .pdf copy that I got my hands on.

I don't reproduce all references. It's too long anyway.

Claim:

As he starts to speak, her brain carefully searches to see if what he says is congruent with his tone of voice. If the tone and meaning do not match, her brain will activate wildly. Her cortex, the place for analytical thinking, would try to make sense of this mismatch. She detects a subtle incongruence in his tone of voice—it is a little too over-the-top for his protestations of innocence and devotion. His eyes are darting a bit too much for her to believe what he is saying. The meaning of his words, the tone of his voice, and the expression in his eyes do not match. She knows: he is lying. (p. 118–119)

Sources:

• Schirmer, A., S. A. Kotz, et al. (2002). “Sex differentiates the role of emotional prosody during word processing.” Brain Res Cogn Brain Res 14 (2): 228–33.
• Schirmer, A., S. A. Kotz, et al. (2005). “On the role of attention for the processing of emotions in speech: Sex differences revisited.” Brain Res Cogn Brain Res 24 (3): 442–52.
• Schirmer, A., T. Striano, et al. (2005). “Sex differences in the preattentive processing of vocal emotional expressions.” Neuroreport 16 (6): 635–39.

The first study found that "women make an earlier use of emotional prosody during word processing as compared to men," while the second found that "the presence of sex differences in emotional-prosodic priming depends on whether or not participants are instructed to take emotional prosody into account."

The third one seems to have investigated the detection of meaning/tone-of-voice mismatches and the abstract states: "Independent of the listeners' sex, deviants elicited a mismatch negativity in the scalp-recorded event-related potential as an indicator of preattentive acoustic change detection. Only women, however, showed a larger mismatch negativity to emotional than to neutral deviants."

Claim:

Maneuvering like an F-15, Sarah’s female brain is a high-performance emotion machine—geared to tracking, moment by moment, the non-verbal signals of the innermost feelings of others. (p. 119)

Source:

• Brody, L. R. (1985). “Gender differences in emotional development: A review of theories and research.” J Pers 53:102–49.

From the abstract: "Studies suggest that with development, boys increasingly inhibit the expression and attribution of most emotions, whereas girls increasingly inhibit the expression and recognition of socially unacceptable emotions, e g, anger. These differences may be a function of different socialization processes for males and females, which may be adaptations to innate gender differences in temperament, or adaptations to existing sociocultural pressures."

Claim:

By contrast, Nick, like most males, according to scientists, is not as adept at reading facial expressions and emotional nuance—especially signs of despair and distress. (p. 119)

Source:

• Hall, L. A., A. R. Peden, et al. (2004). “Parental bonding: A key factor for mental health of college women.” Issues Ment Health Nurs 25 (3): 277–91.

This paper is about the kinds of parent-child relationships that are predictive of depression in college-aged women.This appears to have no relation to the claim made above.

Claim:

Women know things about the people around them—they feel a teenage child’s distress, a husband’s flickering thoughts about his career, a friend’s happiness in achieving a goal, or a spouse’s infidelity at a gut level. (p. 120)

Source:

• Naliboff, B. D., S. Berman, et al. (2003). “Sex-related differences in IBS patients: Central processing of visceral stimuli.” Gastroenterology 124 (7): 1738–47.

IBS is "irritable bowel syndrome," the stomach disease. From what I understand, the researchers did a PET scan of patients that either currently had a "moderate rectal inflation" or were merely asked to think about one.

Their conclusions were that among the people with inflamed intestines, "women showed greater activation in the ventromedial prefrontal cortex, right anterior cingulate cortex, and left amygdala, whereas men showed greater activation of the right dorsolateral prefrontal cortex, insula, and dorsal pons/periaqueductal gray. Similar differences were observed during the anticipation condition. Men also reported higher arousal and lower fatigue."

So it seems that there are sex differences in the way we react to diarrhea. I'm not sure that tells us much about "gut feelings."

Claim:

Some of this increased gut feeling may have to do with the number of cells available in a woman’s brain to track body sensations. After puberty, they increase. (p. 120)

Source:

• Leresche, L., L. A. Mancl, et al. (2005). “Relationship of pain and symptoms to
  pubertal development in adolescents.” Pain 118 (1–2): 201–9.

This study showed, based on questionnaires, that an array of different pain symptoms become more common as girls and boys reach puberty. From the abstract:

Prevalence of back pain, headache and [jaw] pain increased significantly … and stomach pain increased marginally with increasing pubertal development in girls. Rates of somatization, depression and probability of experiencing multiple pains also increased with pubertal development in girls (P<0.0001). For boys, prevalence of back … and facial pain … increased, stomach pain decreased somewhat and headache prevalence was virtually unchanged with increasing maturity. For both sexes, pubertal development was a better predictor of pain than was age.

This does not prove anything about the underlying brain substrates. It only tracks who hurt in what way, according to their own reports.

Claim:

The estrogen increase means that girls feel gut sensations and physical pain more than boys do. (p. 120)

Sources:

• Lawal, A., M. Kern, et al. (2005). “Cingulate cortex: A closer look at its gut-related functional topography.” Am J Physiol Gastrointest Liver Physiol 289(4): G722–30.
• Derbyshire, S. W., T. E. Nichols, et al. (2002). “Gender differences in patterns of cerebral activation during equal experience of painful laser stimulation.” J Pain 3 (5): 401–11.

The first of these studies is an MRI study of where in the brain the two genders predominantly show activity when they feel or think about pain in the rectum.

They showed some similarities, but also differences in terms of the activity in the front part of the limbic cortex, which according to Wikipedia "appears to play a role in a wide variety of autonomic functions, such as regulating blood pressure and heart rate." There was also a difference depending on whether they consciously thinking about their gut: "In contrast to male subjects, females exhibit increased activity in response to liminal nonpainful stimulation compared with subliminal stimulation suggesting differences in cognition-related recruitment."

But I'd have to check the details to be sure of how the subjects were actually stimulated. But as far as I can see, the paper is not actually about differences in how the genders feel, but only in what their brains look like in the scanner.

The second study, Derbyshire et al, zapped men and women with an equal amount of laser energy to the back of their hand and recorded where their brains lit up:

The female subjects required less laser energy before reporting pain, but the difference was not significant. … There was significantly greater activation in the left, contralateral, prefrontal, primary and secondary somatosensory, parietal, and insula cortices in the male subjects compared with the female subjects and greater response in the perigenual cingulate cortex in the female subjects.

So, "girls feel … physical pain more than boys do"? Perhaps, but this study doesn't conclude that.

Claim:

Some scientists speculate that this greater body sensation in women punches up the brain’s ability to track and feel painful emotions, too, as they register in the body. (p. 120)

Source:

• Lawal, op. cit.

Claim:

The areas of the brain that track gut feelings are larger and more sensitive in the female brain, according to brain scan studies. (p. 120)

Source:

• Butler, T., H. Pan, et al. (2005). “Fear-related activity in subgenual anterior cingulate differs between men and women.” Neuroreport 16 (11): 1233–36.

This study trained subjects to have a fear response by giving them mild electric shocks, and then recorded what their brain activity looked like. The women in the study showed more activity in the "deep" brain structures, and the authors concluded that this suggested a "greater susceptibility of women to anxiety."

I'm not sure the paper said anything about the gut, or about the size of the relevant brain structures, though. But perhaps there is a remark about that somewhere in there.

Claim:

Therefore, the relationship between a woman’s gut feelings and her intuitive hunches is grounded in biology. (p. 120)

Source:

• Levenson, R. W. (2003). “Blood, sweat, and fears: The autonomic architecture of emotion.” Ann NY Acad Sci 1000:348–66.

I don't know exactly what she's referring to here. The paper does have one short section (9 sentences) on the organ responses that follow from emotional reactions though. Its conclusion:

Although the primary role of the [autonomous nervous system] in emotion is usually thought to be providing physiological support for action, many of these autonomic adjustments [e.g., erection, dilation of pupils, sweating] create appearance changes that have strong signal value. Most prominent are those that produce visible changes in color, moisture, protrusion, and in the appearance of the eyes. … That humans make decisions, plan strategies, and regulate their behavior in response to these signs of underlying autonomic activity in others underscores the utility and value of these signs as indicators of emotional states. (pp. 356-357)

So are "a woman’s gut feelings … grounded in biology"? This paper rather seems to say that your literal inner organs have a certain reaction for a certain evolutionary purposes, although the claim is far from fleshed out.

Claim:

When a woman begins receiving emotional data through butterflies in her stomach or a clench in the gut—as Sarah did when she finally asked Nick if he was seeing someone else—her body sends a message back to the insula and anterior cingulate cortex. The insula is an area in an old part of the brain where gut feelings are first processed. The anterior cingulate cortex, which is larger and more easily activated in females, is a critical area for anticipating, judging, controlling, and integrating negative emotions. A woman’s pulse rate jumps, a knot forms in her stomach—and the brain interprets it as an intense emotion. (p. 120)

Sources:

• Butler, op. cit. (the electric shock study)
• Pujol, J., A. Lopez, et al. (2002). “Anatomical variability of the anterior cingulate gyrus and basic dimensions of human personality.” Neuroimage 15 (4): 847–55.

The study by Pujol et al. actually does have some relevance here. They measured the size and symmetry of the anterior limbic cortex in 50 men and 50 women, and then saw if they could find any correlations between asymmetries and personality traits. It turns out they could, as women tended to have a more asymmetric cingulate cortices, and be more fearful:

Anatomical data revealed that … a prominent right anterior cingulate was more frequent in women than in men. … Both women and men with larger right anterior cingulate described themselves as experiencing greater worry about possible problems, fearfulness in the face of uncertainty, shyness with strangers, and fatigability. … Our observations suggest that a large right anterior cingulate is related to a temperamental disposition to fear and anticipatory worry in both genders and that a higher prevalence of these traits in women may be coupled with a greater expansion of this brain region.

Note that the personality test they used is based on self-reported character traits. 31 out of the 50 women had a larger right anterior cingulate, while this was true for 21 of the men. About 24% of the variance on the so-called Harm Avoidance personality trait was accounted for by the larger size of the right anterior cingulate.

This study gets bonus points for including images of two brains that look different (p. 848):

Always worth reminding oneself that the goop inside your head or my head may only resemble the standard textbook brain very loosely.

Let's take a step back: What did Brizendine actually claim? First, that the anterior cingulate cortex is "larger and more easily activated in females," and second, that when "a woman" experiences physiological responses like increased pusle, "the brain interprets it as an intense emotion. "

Both of these claims seem to be substantiated by the studies, although the gender differences are quite small. For instance, the average surface area of the anterior cingulate gyrus in women was 946 mm squared (s.d. = 204), while the corresponding number for the men was 918 mm squared (s.d. = 256). Clearly, these two populations do not differ significantly (see also Pujol et al.'s own statistical analysis, p. 850).

Claim:

Jane’s observations were so minute that to Evan she appeared to be reading his mind. This often unnerved him. Jane had watched Evan’s eyes and facial expression and correctly inferred what was going on in his brain. (p. 121)

Source:

• Rotter, N. G. (1988). “Sex differences in the encoding and decoding of negative facial emotions.” Journal of Nonverbal Behavior 12:139–48.

From their abstract: "Overall, females exceeded males in their ability to recognize emotions whether expressed by males or by females. As an exception, males were superior to females in recognizing male anger. The findings are discussed in terms of social sex-roles."

Claim:

Men don’t seem to have the same innate ability to read faces and tone of voice for emotional nuance. (p. 121)

Sources:

• Campbell, A. (2005). “Aggression.” In Handbook of Evolutionary Psychology, ed. D. Buss, 628–52. New York: Wiley.
• Rosip, J. C., J. A. Hall (2004). “Knowledge of nonverbal cues, gender, and non-verbal decoding accuracy.” Journal of Nonverbal Behavior, Special Interpersonal Sensitivity, Pt. 2. 28 (4): 267–86.
• Weinberg, M. K. (1999). “Gender differences in emotional expressivity and self-regulation during early infancy.” Dev Psychol 35 (1): 175–88.

Strange that she would use the word "innate" here without providing any documentation.

Claim:

A study at California State University, Sacramento, of psychotherapists’ success with their clients showed that therapists who got the best results had the most emotional congruence with their patients at meaningful junctures in the therapy. These mirroring behaviors showed up simultaneously as the therapists comfortably settled into the climate of the clients’ worlds by establishing good rapport. All of the therapists who showed these responses happened to be women. Girls are years ahead of boys in their ability to judge how they might avoid hurting someone else’s feelings or how a character in a story might be feeling. (pp. 121–122)

Sources:

• Raingruber, B. J. (2001). “Settling into and moving in a climate of care: Styles and patterns of interaction between nurse psychotherapists and clients.” Perspect Psychiatr Care 37 (1): 15–27.
• McClure, E. B. (2000). “A meta-analytic review of sex differences in facial expression processing and their development in infants, children, and adolescents.” Psychol Bull 126 (3): 424–53.
• Hall, J. A. (1978). “Gender effects in decoding nonverbal cues.” Psychol Bull 85: 8845–57.
• Hall, J. A. (1984). Nonverbal sex differences: Communication accuracy and expressive style. Baltimore: Johns Hopkins University Press.

Claim:

This ability might be the result of the mirror neurons firing away, allowing girls not only to observe but also to imitate or mirror the hand gestures, body postures, breathing rates, gazes, and facial expressions of other people as a way of intuiting what they are feeling. (p. 122)

Source:

• None provided.

Claim:

Sometimes, other people’s feelings can overwhelm a woman. My patient Roxy, for example, gasped every time she saw a loved one hurt him- or herself—even when they did something as minor as stub a toe—as if she were feeling their pain. Her mirror neurons were overreacting, but she was demonstrating an extreme form of what the female brain does naturally from childhood and even more in adulthood—experience the pain of another person. (p. 122)

Sources:

• Singer, T., B. Seymour, et al. (2004). “Empathy for pain involves the affective but not sensory components of pain.” Science 303 (5661): 1157–62.
• Idiaka, T. (2001). “Age-related differences in the medial temporal lobe responses to emotional faces.” Society forNeuroscience, New Orleans.
• Zahn-Waxler, C., B. Klimes-Dougan, et al. (2000). “Internalizing problems of
  childhood and adolescence: Prospects, pitfalls, and progress in understanding the development of anxiety and depression.” Dev Psychopathol 12 (3): 443–66.

From Singer et al.: "We assessed brain activity in the female partner while painful stimulation was applied to her or to her partner's right hand through an electrode attached to the back of the hand." They did not perform the reverse study, with the women being zapped.

Idiaka et al. had their subject perform a gender discrimination task while they looked at happy and sad faces, but their study did not actually check for any gender differences in performance.

I haven't been able to get a hold of the last paper, but its abstract makes no reference to a gender dimension.

Claim:

At the Institute of Neurology at University College, London, researchers placed women in an MRI machine while they delivered brief electric shocks, some weak and some strong, to their hands. Next, the hands of the women’s romantic partners were hooked up for the same treatment. The women were signaled as to whether the electric shock to their beloveds’ hands were weak or strong. The female subjects couldn’t see their lovers’ faces or bodies, but even so, the same pain areas of their brains that had activated when they themselves were shocked lit up when they learned their partners were being strongly shocked. The women were feeling their partners’ pain. Like walking in another’s brain, not just his shoes. Researchers have been unable to elicit similar brain responses from men. (pp. 122-123)

Sources:

• Singer, op. cit.
• Singer, T., B. Seymour, et al. (2006). “Empathic neural responses are modulated by the perceived fairness of others.” Nature 439 (7075): 466–69.

These remarks mix up the conclusion of two different studies. This is seriously misleading and not scholarly defensible.

As mentioned before, the first study did not test the men and therefore naturally did not "elicit similar brain responses" from them.

The second study was not a your-lover-is-in-pain study, but an MRI study that investigated how men and women differed in brain response when they were playing a game against a cheater. It concluded that men "empathize with fair opponents while favouring the physical punishment of unfair opponents."

Claim:

In a study on the aftereffects of frightening films, women were more likely to lose sleep than men.

Source:

• Harrison, K., ed. (1999). “Tales from the screen: Enduring fright reactions to scary movies.” Media Psychology, Spring: 15–22.

Sounds reasonable, but is plucked out of thin air: "Sex was not a significant predictor" (p. 108); "we did not find sex differences" (p. 113).

This is clearly a blatant lie, and a quite dumb one at that.

Claim:

In the male brain, most emotions trigger less gut sensation and more rational thought.

Sources:

• Naliboff, op. cit. (the PET scan of people with inflamed bowels)
• Wrase, J., S. Klein, et al. (2003). “Gender differences in the processing of standardized emotional visual stimuli in humans: A functional magnetic resonance imaging study.” Neurosci Lett 348 (1): 41–45.

Another startlingly literal reading of "gut feeling."

The second study showed pictures to 10 men and 10 women and scanned their brains:

Men and women showed no significant difference in valence, arousal, skin conductance response and startle modulation. Only in men was amygdala activation observed in the pleasant condition. Furthermore, men showed a stronger brain activity for positive visual stimuli than women in the frontal lobe (inferior and medial frontal gyrus). In women, stronger brain activation for affectively negative pictures was observed in the anterior and medial cingulate gyrus.

So now the amygdala counts as being rational? That's news to me.

Claim:

A woman, because of her expert ability to read faces, will recognize the pursed lips, the squeezing around the eyes, and the quivering corners of the mouth as preludes to crying. A man will not have seen this buildup, so his response is usually “Why are you crying? Please don’t make such a big deal out of nothing. Being upset is a waste of time.” Researchers conclude that this typical scenario means the male brain must go through a longer process to interpret emotional meaning. (p. 124)

Sources:

• McClure, E. B., C. S. Monk, et al. (2004). “A developmental examination of gender differences in brain engagement during evaluation of threat.” Biol Psychiatry 55 (11): 1047–55.
• Lynam, D. (2004). “Personality pathways to impulsive behavior and their relations to deviance: Results from three samples.” Journal of Quantitative Criminology 20:319–41.
• Dahlen, E. (2004). “Boredom proneness in anger and aggression: Effects of impulsiveness and sensation seeking.” Personality and Individual Differences 37:1615–27.
• Hall, J. A., J. D. Carter, and T. G. Horgan (2000). “Gender differences in the nonverbal communication of emotion.” In A. H. Fischer, ed., Gender and Emotion: Social Psychological Perspectives, 97–117. London: Cambridge University Press.

I couldn't find the first of these studies. The other one seems to be, as the title says, about "impulsive behavior," and I would be surprised if it concludes that "the male brain must go through a longer process to interpret emotional meaning." The third shows that bored people are more aggressive.

The fourth paper is a book chapter. Hall et al. report that there are "relatively large gender differences," but comment:

The word "relatively" is important here. In absolute terms psychological gender differences tend to be rather small. However, the nonverbal differences are larger than many other psychological gender differences (including cognitive skills, attitudes, personality, and other social behaviors) (Hall, 1998). (p. 98)

They are also cautious about biological determinism, reminding the reader that

it is not necessary to posit that differences between males' and females' nonverbal behaviors and skills have evolved biologically (pp. 98–99)

What exactly do "researchers conclude"?

Well, Hall and colleagues conclude that women smile more and are better at it, as well as better at recognizing smiles (p. 112). Had Brizendine only said that, the reference would have provided support for her assertion. Hall et al. do not, however, unambigously attribute this to any specific anatomical or biological cause, so Brizendine is on her own with that claim.

Claim:

Tears in a woman may evoke brain pain in men. The male brain registers helplessness in the face of pain, and such a moment can be extremely difficult for them to tolerate. (p. 124)

Sources:

• Campbell, A. (1993). Out of Control: Men, Women and Aggression. New York: Basic Books.
• Campbell, A. (2005). “Aggression.” (see above)
• Levenson 2003;
• Frey, W. (1985). “Crying: The mystery of tears.” Winston Pr (September 1985).

Claim:

One study showed that newborn girls, less than twenty-four hours old, respond more to the cries of another baby—and to human faces—than do boys. (p. 125)

Source:

• McClure, E. B. (2000). “A meta-analytic review of sex differences in facial expression processing and their development in infants, children, and adolescents.” Psychol Bull 126 (3): 424–53.

I haven't looked this up, but shouldn't a true biofundamentalist predict that women would get better rather than worse at this when they came of child-bearing age? I mean, just for the sake of argument.

Claim:

Men pick up the subtle signs of sadness in a female face only 40 percent of the time, whereas women can pick up these signs 90 percent of the time. (p. 125)

Source:

• Erwin, R. J., R. C. Gur, et al. (1992). “Facial emotion discrimination: I. Task construction and behavioral findings in normal subjects.” Psychiatry Res 42(3): 231–40.

According to the abstract, 24 males and 10 females were asked to look at pictures of male and female faces and judge whether they were happy or sad. The findings were that "males had higher sensitivity scores for the detection of sad emotion. …  Compared with female subjects, male subjects (n = 10) were selectively less sensitive to sad emotion in female faces. Female subjects (n = 10) were more sensitive overall to emotional expression in male faces than in female faces."

10 out of 24 is 41.7%, so I guess that were that number of comes from. 10 out of 10 is more than 90% though, so how did she get that number?

Now that we're at it, how about some confidence intervals? Using Chebyshev's inequality with a 95% confidence level, I find that the first number comes with an uncertainty of up to about 44 percentage points, while the second has an uncertainty of up to 71 percentage points. So let's not build an empire on that result.

Final point, why "subtle"? I haven't seen the experimental materials, but knowing what I know about experimental psychology, I'm sure they were all but subtle.

Claim:

And while men and women are both comfortable being physically close to a happy person, only women report that they feel equally comfortable being close to someone sad.

Source:

• Mandal, M. K. (1985). “Perception of facial affect and physical proximity.” Percept Mot Skills 60 (3): 782.

When she says "physically close to," she means literally physically close to: "The experimental procedure required each S to stand 12 ft away from a life-size facial emotion projected on a screen and to step forward as close to that expression as possible to feel comfortable for interaction." In terms of the mean number of inches, "men preferred to be closer to an expression of happiness (M = 28.0 in.) than to one of sadness (M = 41.9 in.), while women approached both almost equally (sad: M = 23.5 in., happiness: M = 24.5 in.)."

So this claim seems to be warranted by the paper, quite literally.

Claim:

Men are used to avoiding contact with others when they themselves are going through an emotionally rough time. They process their troubles alone and think women would want to do the same. (pp. 125-126)

Source:

• Cross, S. E., and L. Madson (1997). “Models of the self: Self-construals and gender.” Psychol Bull 122 (1): 5–37.

I don't have access to this paper, so I can evaluate this claim entirely. But guessing from the abstract, I think the paper would support the statement that men are supposed to act independent, but not necessarily that they believe women to do the same.