Monday, January 12, 2009

Testosterone shifts the balance between sensitivity for punishment and reward in healthy young women

ResearchBlogging.orgAh, men. We just keep on finding out ways that we're crazy, on average, as compared to women. I've got a little pile of papers on male idiocy, and I'm going to try to write up a couple of them. This one is first for a bunch of reasons, among them:

(1) The journal it is in has a very cool name: Psychoneuroendocrinology. I really would like a paper in that on my CV.

(2) It reports a pretty cool experiment.

(3) I'd already read it.

In a nutshell, this team found that administration of testosterone made healthy young women demonstrably less risk averse and punishment sensitive. Here, as usual, is the full abstract:
Animal research has demonstrated reductions in punishment sensitivity and enhanced reward dependency after testosterone administration. In humans, elevated levels of testosterone have been associated with violent and antisocial behavior. Interestingly, extreme forms of violent and antisocial behavior can be observed in the psychopath. Moreover, it has been argued that reduced punishment sensitivity and heightened reward dependency are crucially involved in the etiology and maintenance of psychopathy. A task that has been proven to be capable of simulating punishment-reward contingencies is the IOWA gambling task. Decisions to choose from decks of cards become motivated by punishment and reward schedules inherent in the task. Importantly, clinical and subclinical psychopaths demonstrate a risky, disadvantageous pattern of decision-making in the task, indicating motivational imbalance (insensitivity for punishment and enhanced reward dependency). Here, in a double-blind placebo-controlled crossover design (n = 12), whether a single administration of testosterone would shift the motivational balance between the sensitivity for punishment and reward towards this tendency to choose disadvantageously was investigated. As hypothesized, subjects showed a more disadvantageous pattern of decision-making after testosterone compared to placebo administration. These findings not only provide the first direct evidence for the effects of testosterone on punishment-reward contingencies in humans, but they also give further insights into the hypothetical link between testosterone and psychopathy.

The paper does pretty much what it says on the box. The experiment was partly occasioned by existing work showing that testosterone affected punishment sensitivity and aggression in animals, which in turn suggests that it may play a role in psychopathy. Jack van Honk (of Utrecht University) and fellow researchers rounded up "12 healthy young women ranging in age from 20 to 25 years" and established absence of psychopathology and substance abuse by interview. Testing was conducted during the follicular phase of the menstrual cycle, "because of the low and stable levels of sex hormones during this period". Each subject received a single dose (0.5mg) of testosterone or a placebo, with the testosterone administration leading to a "10-fold increase in total testosterone". This dosage had been previously established to lead to "significantly elevated physiological responsiveness (vaginal pulse amplitude) in healthy young women after about 4 hours".

Yes, that's right: vaginal pulse amplitude. In case you were wondering (and who wouldn't be) this is the "only physiological response known to possess a
non-habitual nature, thus allowing multiple measures throughout the day". This non-habituating response also justified the 4 hour delay from administration to the other assessment. They don't say how they measured it.

Besides the physiological measure just described, subjects completed a mood assessment by self-report, and the IOWA gambling task. In this task subjects select cards from four decks paying hypothetical rewards and giving (sometimes) hypothetical penalties. Subjects get to chose 100 cards. Two decks are net advantageous, two net disadvantageous, but the 'bad' decks give larger payouts sometimes. Many take it that persistence with the 'bad' decks indicates low sensitivity to punishment or risk. Scoring usually (and here) divides the 100 draws into 5 blocks (of 20) and reflects the relative fraction of good and bad choices for the block.

I've got my doubts about the IOWA task, of which more shortly. That aside, the team found the following:

So more testosterone makes you madder, in the sense of sticking with high payout courses of action that on balance are net punishers, as compared to those less hopped up on the knacker water. Bear in mind that the 10-fold increase left the healthy young women with less of the stuff than the average male of the same age.

I should also mention that van Honk's group has done a pile of other work on testosterone and decision making. If there's a useful web page listing the work, it's been cunningly hidden, but I'm going to blog more of it, and citation indexes will help find it too.

Getting back to my worries about the IOWA task, I don't see why there are four decks instead of two (although this may not matter). I don't see why the instrument combines so many things in such a dirty way, since there are varying magnitudes and frequencies of both rewards and punishments, and the contingencies are unknown to the subject. As a good behaviourist I want to know why individual assessments for sensitivity to delay, and risk, and punishment aren't performed separately and rigorously, and why there isn't something real at stake for the subjects (whose choices don't in fact lead to real reward or punishment). There are some odd results with the IOWA task as well - Chiu and colleagues (2005) found that making new decks with the same net rates of reward but different frequencies of payment led to 'normal' subjects chosing differently, and higher levels of education leads to worsened performance on the IGT (Evans and Colleagues 2004).

Finally, here's a semi-serious question, although it means I'll never be President of Harvard: Does the same protocol lead to any measurable difference in mathematical ability?

References:


Chiu, Y-C., Lin, C-H., Huang, J-T., Lin, S., Lee, P-L, and Hsie, J-C. (2005). Immediate gain is long-term loss: Are there foresighted decision makers in Iowa Gambling Task? (Presentation at the third meeting of the Society for Neuroeconomics, Kiawah Island, September, 2005.)

Evans, C., Kemish, K., and Turnbull, O. (2004). Paradoxical effects of education on the Iowa Gambling Task. Brain and Cognition 54: 240–244.

J van Honk, Dennis J.L.G. Schuttera, Erno J. Hermansa, Peter Putmana, Adriaan Tuitena, Hans Koppeschaar (2004). Testosterone shifts the balance between sensitivity for punishment and reward in healthy young women Psychoneuroendocrinology, 29 (7), 937-943 DOI: 10.1016/j.psyneuen.2003.08.007

Postscript 24 January 2009: Here's a related piece on BBC News, by Simon Baron-Cohen. I doubt anyone knows any more about autism. Or that's what my mate Dave says.

5 comments:

katherine said...

To your question about mathematical ability...the protocol would seem to lessen mathematical ability, given that it makes the young women into worse gamblers.

Right?

Michael Meadon said...

Interesting. And, yeah, I think you're right about the Iowa protocol - make 'em play for real money at least.

Oh. And I'm SOOOO working "vaginal pulse amplitude" into my next idle conversation with a stranger...

Doctor Spurt said...

Well I don't know whether lessened aversion to token hypothetical risk means anything specific about ability at mathematical reasoning, Katherine. Maybe doing it well needs some level of boldness or confidence and being hopped up on testosterone could even help? (I heard anecdotally of a mathematician who dealt with a confidence problem and did sterling work with the temporary aid of great piles of cocaine.

And Michael, by golly yes. There's one to "use in a sentence".

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