The Frontal Cortex

The Placebo Effect of Biology

Posted by Jonah Lehrer on December 15, 2009
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The always fascinating Ed Yong, over at Not Exactly Rocket Science, highlights a recent study on testosterone, aggression and the placebo effect.

If ever a hormone was the subject of clichés and stereotypes, it is testosterone. In pop culture, it has become synonymous with masculinity, although women are subject to its influence too. Injections of testosterone can make lab rats more aggressive, and this link is widely applied to humans. The media portrays “testosterone-charged” people as sex-crazed and financially flippant and the apparent link with violence is so pervasive that the use of steroids has even been used as a legal defence in a US court.

Christoph Eisenegger from the University of Zurich tested this folk wisdom by enrolling 60 women in a double-blind randomised controlled trial. They were randomly given either a 0.5 milligram drop of testosterone or a placebo. He only recruited women because previous research shows exactly how much testosterone you need to have an effect, and how long it takes to do so. We don’t know that for men.

The women couldn’t have known which substance they were given, but Eisenegger asked them to guess anyway. Their answers confirmed that they couldn’t tell the difference between the two drops. But they would also confirm something more startling by the trial’s end.

Each woman was paired with a partner (from another group of 60) and played an “Ultimatum game” for a pot of ten Swiss francs. One woman, the “proposer”, decided how to allocate it and her partner, “the responder” could choose to accept or refuse the offer. If she accepts, the money is split as suggested and if she refuses, both players go empty-handed. The fairest split would be an equal one but from the responder’s point of view, any money would be better than nothing. The game rarely plays out like that though – so disgusted are humans with unfairness that responders tend to reject low offers, sacrificing their own meagre gains to spite their proposers.

Overall, Eisenegger found that women under the influence of testosterone actually offered more money to their partners than those who received the placebo. The effect was statistically significant and it’s exactly the opposite of the selfish, risk-taking, antagonistic behaviour that stereotypes would have us predict.

Those behaviours only surfaced if women thought they had been given testosterone. Those women made lower offers than their peers who believed they had tasted a placebo, regardless of which drop they had been given. The amazing thing is that this negative ‘imagined’ effect actually outweighed the positive ‘real’ one. On average, a drop of testosterone increased a proposer’s offer by 0.6 units, but belief in the hormone’s effects reduced the offer by 0.9 units.

The larger point is that our beliefs about biology – those stupid cliches about sex hormones, for instance – often overwhelm the actual effects of biology. Thanks to some evolutionary innovations (like that overhang of brain called the prefrontal cortex), we’re able to suppress our aggressive feelings and turn off our anger. We can resist even the most primal urges. And yet, all it takes is a whiff of imaginary testosterone before we start behaving like selfish hominids, imitating what we assume is our “natural” state.

Here’s a question: does all this new knowledge about the brain undermine our natural ability to restrain ourselves? Have we become prisoners of incomplete science? When we learn that the amygdala is an ancient part of human nature, pumping out fear and anger, does that make it harder to resist the amygdala? When we learn that sugar activates the same dopaminergic areas as sex and crack, does that make it harder to not eat the candy bar? The brain has preserved a small space for executive control, which is a weak synonym for free will. Is modern neuroscience, by describing the determinism of the fleshy machine, undermining that sense of control? My worry is that we’ve come to see our imperfections as inevitable, just like those testosterone fueled subjects acting greedy in the ultimatum game.

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  1. #1 catgirl
    December 15, 2009

    I have hypothyroidism, so I don’t produce enough thyroid hormones. What I’ve realized since my diagnosis is that most people have no idea what “hormone” even means. If I even mention the word “hormone”, people just think of horny teenagers and emotional pregnant women. I even had one coworker say that I should warn him if I forgot to take my thyroid hormone pill. But people don’t realize that hormones effect so many things besides mood.

  2. #2 Elye
    December 16, 2009

    It may be true that people don’t understand testosterone (or hormones) and simply mean to describe those primal habits (Frat-boys? Video example Is there a better word to describe that personality type?).

    It also depends whether they use their belief in biological effects to compensate for their Natural tendencies or to make excuses for bad behavior.

  3. #3 Brandon
    December 16, 2009

    I shared with my girlfriend that I had been having “irrational” thoughts of jealousy about her recently having a drink with an ex-boyfriend who was in town for a funeral. I say “irrational,” because I completely trust her and know in the deepest part of my heart that she loves me. When she asked me why I was feeling jealous, I responded that it’s because I’m a human male, just as my understanding of evolutionary psychology would have me believe. I am unable to decide if my somewhat-informed understanding of jealousy helped quell the feeling or sapped me of some of my will to fight it. I’d like to believe that in this case, more knowledge enabled me to make a more informed decision on how to interpret my feelings.

  4. #4 Brian
    December 17, 2009

    What if Tiger believed that he received testosterone medications…?

  5. #5 Rosey
    December 17, 2009

    This reminds me of the response to Wilson’s Sociobiology, way back when. Just because I’m hormonally PREDISPOSED to do this, or that, doesn’t mean that I’m PREDETERMINED to do this or that. I think it’s easier to KNOW that I’m likely to feel jealous and chose consciously not to act on it, than to not know where the feeling is coming from and perhaps take it more seriously than is warranted. Bringing to consciousness as many of our predispositions, twitches, automatic reactions and impulses as we possibly can means that we’re able to exercise some choice in the matter of action. Without consciousness we’re at the mercy of our impulses.

  6. #6 Ray in Seattle
    December 18, 2009

    Rosey, I’d add that bringing to consciousness whatever mental state we are experiencing also brings to bear whatever social beliefs we have acquired about those mental states.

    For example, in some cultures it is expected that fathers may become uncontrollably and understandably violent if a daughter socializes with men who are not in the family.

    In many minds those social beliefs are far stronger than a father’s instinctive feelings of compassion and nurturance for his daughter – and those stronger social emotions may cause him to hurt her.

    It’s remotely possible that reason may be enlisted to analyze such a situation before the father acts – but reason is seldom enlisted in such an emotional context. When it is – it is to justify whatever actions are induced by the raging emotions of the moment – not to calmly consider one’s options and the long term consequences.

    So, consciousness is a double-edged sword and its application in any situation depends on the relevant social beliefs that already populate that mind and that always have far greater force than reason in a moment of crisis.

  7. #7 Rosey
    December 18, 2009

    I dunno Ray, I don’t believe or see any evidence for fathers being “instinctively” compassionate or nurturing towards their daughters. Often fathers do feel these things towards their daughters, when they have actual relationships with them (which many fathers don’t) but there’s nothing instinctive about it. I think in some cultures fathers see daughters, and other female relatives, as property. Any attempt by a stranger to “use” the father’s property will be met with resistance. I completely agree that these actions on the part of those dominant entities are socially constructed and won’t be curtailed by any raising of consciousness: the male in your case is perfectly aware that his behavior is socially acceptable. In fact, it’s demanded of males in some cultures if they wish to maintain their status as male.

    But I’m not sure I follow you about what this has to do with the question I thought we were addressing: is it better to know the truth about our impulses and where they originate, or does knowing make us more likely to act on them.

  8. #8 Ray in Seattle
    December 19, 2009

    Rosey, I hope you can forgive my inability to easily explain myself on this topic but I think it very unlikely that evolution would have produced human fathers without some instinctive feelings of protection and nurturance for their offspring. I’d say that a father’s treatment of their child though, in any instance, is the result of emotional forces from many sources in the mind acting concurrently.

    There are times when a father’s anger at a child can overcome the instinct for protection and cause him to hurt the child. There are times when the forces of social emotions (cultural beliefs and the fear of social ridicule) may cause the father even to kill a child whose behavior invites social disapproval of the family and his leadership. The instinct for protection did not disappear at these times but was overpowered by much stronger opposing emotional forces at that moment.

    Re: your last paragraph, IMO being aware of our mental states can help us make better behavior decisions. We may value rationality for example, and train ourselves to be aware of strong emotions at those times when they might lead us astray.

    But this is difficult for humans. Whether we can be successful at it depends on how strongly we believe in the correctness of our rational behavior choice situation – vs how strong any opposing emotional forces are at that moment. But in the brink it is still the stronger net emotional force that will lead us one way or the other.

    In my view reasoning itself has no intrinsic ability to mediate behavior. It is only the emotions that arise as a result of the reasoning that we attach to a behavior candidate that become part of the behavior equation. They may win or may not in any transaction. Even if they win there’s no guarantee of rational behavior. Human reasoning itself is often inadequate or it’s motivated by bias, there may not be enough data, the data could be wrong, etc.

    Actually, those times when we make crucial behavior decisions in life are usually times of high emotional stress when the brain is even less capable of rational deliberation. It is then more likely that the emotions of existing beliefs fortified by our past experiences become the determining factor. Evolution has designed us this way because it works. That’s why soldiers are trained not to think but to react as they were trained in battle situations. When the smoke clears we then use our intellect to justify our behavior to ourselves and others and to mitigate any negative consequences.

  9. #9 meryl
    December 19, 2009

    I think about a woman who constantly complains that she is obese because she has inherited low metabolic rate. Meantime, she chomps down bags of herseys every day. hmmm..

    Whenever she says that to me, I’ve immeditately thought, uhm if your metabolic rate is low, then why don’t you try to increase your physical activity to improve it? And why are you still chomping down bags of chocolates everyday?

    Her answers “it is precisely my low metabolic rate that I can’t find the motivation to exercise, and it is this low metabolic rate that makes me want to eat chocolates so that I have more energy.”

    There is always an excuse for a weakness; hereditary, or environmental, or perceived, or imagined, or self inflicted, if you are bent on finding one to justify whichever reality you do not want to confront.

    Then, the oddest thing is, you see people with no legs running maranthons.

    Uhm…the diversity of humanity.

    Enjoy enjoy!

  10. #10 Paul H
    December 20, 2009

    As an HIV person on meds, I am on testosterone at the moment. It now comes in a can, and you rub in six squirts a day!

    It did seem to make me more aggressive for a few weeks, but the major effect is that I can respond to the world erotically again. This is nothing to do with sex, but may have something to do with dreams about sex. The main thing is that when I read, about sex and other things, I get *engaged* again.

    In other words it seems to work as a mild anti-depressant.

  11. #11 Associated Counsellors & Psychologists Sydney
    December 27, 2009

    Its a constant issue for us Psychologists & Therapists. Is describing the action causing the effect? Great post.

    Thanks
    Associated Counsellors & Psychologists Sydney
    http://www.counsellingsydney.com.au/surry-hills

  12. #12 Clare Mann
    January 22, 2010

    Our tendency to want to look for concrete answers forces us down a path looking for certainty. The current medical model seemingly provides such certainty and yet advances each day reveal what we thought was not true to become true.

    For example the work of Dr Bruce Lipton portrays a very different theory about genetics and predisposition to illness. I encourage all my clients to keep an open mind and focus on what is important, i.e. empowering clients to overcome their challenges.

    Clare Mann
    Sydney Psychologist