Wednesday, December 9, 2009

Testosterone, Aggression... Confusion

This study (and here) debunks the stereotype that usually applies to Testosterone. A typical stereotype goes like this - Testosterone makes us aggressive which can lead us to lose rationality (matter over mind). This study induced unwarranted dissonance than the researches would have ever expected and clearly paving the way to include umwelt (yes, we are not alone inside our body), social and cultural significance (and so on ad infinitum) in lot of future studies. Until personalized medicine, research et al enters the zone, these dissonances are bound to happen. One size never fits all but that doesn't mean we should stop trusting these experiments. It instigates us to develop an innate tendency to be skeptic but also to applaud and laud the scientifc process and in time we will find a way to balance between the two, enabling us to move forward as a civilization.

"This is a game for two players. One, the Proposer, is given some money, and then has to offer to give a certain proportion of it to the other player, the Receiver. If the Receiver accepts the offer, both players get the agreed-upon amount of money. If they reject it, however, no-one gets anything.

The Proposer is basically faced with the choice of making a "fair" offer, e.g. giving away 50%, or a greedy one, say offering 10% and keeping 90% for themselves. Receivers generally accept fair offers, but most people get annoyed or insulted by unfair ones, and reject them, even though this means they lose money (10% of the money is still more than 0%).

What happened? Testosterone affected behaviour. It had no effect on women playing the role of the Receivers, but the Proposers given testosterone made significantly fairer offers on average, compared to those given placebo. That's not mind over matter, that's matter over mind - give someone a hormone and their behaviour changes.

The direction of the effect is quite interesting - if testosterone increased aggression, as popular belief has it, you might expect it to decrease fair offers. Or, you might not. I suppose it depends on your understanding of "aggression". For their part, Eisenegger et al interpret this finding as suggesting that testosterone doesn't increase aggression per se, but rather increases our motivation to achieve "status", which leads to Proposers making fairer offers, so as to appear nicer.

But where did the BBC get the whole "all in the mind" thing from? Well, after the testing was over, the authors asked the women whether they thought they had taken testosterone or placebo. The results showed that the women couldn't actually tell which they'd had - they were no more accurate than if they were guessing - but women who believed they'd got testosterone made more unfair offers than women who believed they got placebo. The size of this effect was bigger than the effect of testosterone.

Is that "mind over matter"? Do beliefs about testosterone exert a more powerful effect on behaviour than testosterone itself? Maybe they do, but these data don't tell us anything about that. The women's beliefs weren't manipulated in any way in this trial, so as an experiment it couldn't investigate belief effects. In order to show that belief alters behaviour, you'd need to control beliefs. You could randomly assign some subjects to be told they were taking testosterone, and compare them to others told they were on placebo, say.

This study didn't do anything like that. Beliefs about testosterone were only correlated with behaviour, and unless someone's changed the rules recently, correlation isn't causation.
Overall, this study provides quite interesting data about hormonal effects on behaviour, but tells us nothing about the effects of beliefs about hormones. On that issue, the way the media have covered this experiment is rather more informative than the experiment itself."

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