Thursday, March 3, 2011

Decision-makers betrayed by their wide eyes

09 March 2010 by Ewen Callaway
Magazine issue 2750. Subscribe and save
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WHY can't teachers keep a secret? Because their pupils give them away. It turns out that when people make decisions, their pupils dilate, a subtle cue that could be used to predict a person's intentions, or even converse with people with locked-in syndrome.

It is well known that pupils dilate as it gets darker, and in stressful situations as part of the "fight-or-flight" response. The reflex is mediated by the release of the hormone noradrenalin, which in animals has also been implicated in memory and decision-making. Olivia Carter, a neuroscientist at the University of Melbourne in Australia, wondered if noradrenalin - and by implication pupil dilation - might also be linked to human cognition.

To investigate, her team asked volunteers to pick one of five random digits that displayed on a monitor one after another for 2 seconds each, and to press a button indicating their choice after ...

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