For an actor, the performance conditions weren't exactly ideal: flat on her back in a large machine, under strict instructions to lie as still as possible, speaking in short bursts interspersed with the shrill sound of a magnetic resonance imaging scanner.
But last week Fiona Shaw, one of Britain's leading actresses - who has in her time played everything from the tragic heroine Medea to Shakespeare's Richard II - volunteered in the cause of science to spend an hour having her brain scanned while "acting".
Fiona Shaw's brain appears to be adapted to acting
Professor Sophie Scott of the Institute of Cognitive Neuroscience at University College London wanted to know what happens physically in an actor's head when they pretend to be someone else.
She hoped that scanning Fiona's brain in action would be able to tell us.
The scanner works by measuring blood flow to different parts of the brain. The harder a part is working, the more blood flows into it.
The parts of the brain that control speech are well known: what Prof Scott wanted to know was whether other parts of the brain would also "light up" when actors speak in character rather than as themselves.
The results of the experiment will be on display as part of the Wellcome Collection's new exhibition on identity.
Prof Scott, who is also a Wellcome senior fellow, says our speech and the way we use language are important components of our identity - and one of the ways actors seek to convince their audience that they are another person is of course by changing their voice.
For the experiment, Fiona Shaw performed snatches of T S Eliot's poem The Waste Land. (Appropriately enough, given the circumstances, Eliot's original title for the poem was He Do the Police in Different Voices.)
Fiona's right brain while counting
The poem's second section, A Game at Chess, includes a dialogue between a married couple, and a passage in which a Cockney woman gossips in a pub near closing, interrupted by the voice of the landlord shouting "Hurry up please it's time!".
The text was cut up into sections lasting just a few seconds each. Fiona read them in character, then stopped while the machine scanned her brain.
Then she'd do some counting, so the machine could register what her brain was doing when she was merely speaking; and then she'd do nothing, so the machine could scan her brain at rest.
Fiona Shaw herself says that when performing she uses visual images to help conjure up a character. And sure enough, when the results of the scan were analysed, several parts of her brain were "recruited" to help with her performance beyond those employed when she was speaking neutrally.
One of the accompanying animations shows, in green, the three main parts of her brain which Fiona used when she was simply counting: they are the part which controls the movement of the lips and tongue, the part associated with hearing and a third part involved in planning what she was going to say.
Fiona's right brain while acting
The second animation shows the parts, in yellow, which she also employed when "performing". Towards the front of the brain there is a part associated with "higher order" control of behaviour. Towards the top of the brain is a section which controls the movement of the hands and arms - even though she wasn't waving her arms about, she was apparently thinking about doing so.
And towards the back of the head is an area associated with complex visual imagery, even though she wasn't performing a complex visual task.
The scan backs up work Sophie Scott has done with professional impressionists, whose brains also conjure up visual images of the people they're imitating. What's significant is that a serious actor uses the same technique, even when she's not trying to imitate a real person.
Quite what all this tells us about our identity I'm not so sure. Perhaps it's just this: that convincing people you're someone you're not by changing your voice is hard work - a lot harder than simply being yourself.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.