Saturday, December 02, 2006

Oxytocin and Mind Reading...

...or, I Can See It In Your Eyes.

No, not that kind of "mind reading," but the ability to decode another person's mental state, also called theory of mind. In a study by Domes and colleagues (2006), the neurohormone oxytocin, peddled as the "trust drug" by many shady internet dealers, was administered to male subjects performing a theory of mind task.

[As an aside, nasally administered oxytocin does apparently cross the blood brain barrier designed to keep out foreign agents. I wasn't sure it crossed the BBB, but there you go.]

Anyway, the Reading the Mind in the Eyes task (see Baron Cohen... no, no joking! the OTHER Baron-Cohen) was administered after oxytocin or placebo. The RMET
tests a specific facet of mind-reading, that is, inference of the internal state from subtle affective facial expressions rather than mind-reading in general. Because the RMET was originally developed to measure severe impairments in mindreading capability in adults with autism spectrum disorders, we circumvented possible ceiling effects in healthy subjects by dividing the 36 items into two subsets of easy and difficult items.
Lo and behold, there was a tiny but statistically significant improvement in performance for oxytocin vs. placebo:
Compared with placebo, oxytocin improved performance on the RMET in 20 of the 30 participants. This resulted in a significant mean increase of approximately 3% correct responses (mean +/- SD: placebo: 69.4 +/- 8.1; oxytocin: 72.4 +/- 8.6; t=2.18, p=.019, one-sided).
But a breakdown of hard-to-read vs. easy-to-read eyes revealed that the benefit was entirely for the former.
Domes G, Heinrichs M, Michel A, Berger C, Herpertz SC. (2006). Oxytocin improves "Mind-Reading" in humans. Biol Psychiatry. Nov 28; [Epub ahead of print]

BACKGROUND: The ability to "read the mind" of other individuals, that is, to infer their mental state by interpreting subtle social cues, is indispensable in human social interaction. The neuropeptide oxytocin plays a central role in social approach behavior in nonhuman mammals. METHODS: In a double-blind, placebo-controlled, within-subject design, 30 healthy male volunteers were tested for their ability to infer the affective mental state of others using the Reading the Mind in the Eyes Test (RMET) after intranasal administration of 24 IU oxytocin. RESULTS: Oxytocin improved performance on the RMET compared with placebo. This effect was pronounced for difficult compared with easy items. CONCLUSIONS: Our data suggest that oxytocin improves the ability to infer the mental state of others from social cues of the eye region. Oxytocin might play a role in the pathogenesis of autism spectrum disorder, which is characterized by severe social impairment.
But...but...supposedly women will trust you more after spraying some oxytocin in their vicinity. Now we find out that they'll also be better able to read your mind.1

1 That's assuming the results from male participants will also hold for females.

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