Colin Camerer and Dean Mobbs, ‘Differences in Behaviour and Brain Activity during Hypothetical and Real Choices’, Trends in Cognitive Sciences, 21 (2017), 46-56.

So they’re going to tell me about the difference between real and imaginary? Excellent. The premise is more modest than that, but a very important one, I think. Many experiments test how our minds work by seeing how we react to hypothetical scenarios or stimuli ‘that lack some realistic features’. Do these necessarily elicit our true responses, the ones that would arise in reality, which is what the experimenters are pursuing?
      For example, that classic question: there’s a runaway train, and it’s going to run over five people, but if you press a nearby lever, then you’ll divert the train with the consequence that it will run over one person. What would you do? My reaction tends to be that I refuse to think about something so contrived. But perhaps I’m intimating that my answer would be meaningless, that all the nuances of reality (can anyone see me? how hard is the lever to pull and is it right by me? etc.) would influence things, and that you just can’t imagine what you’d do. I’m probably too grumpy for hypotheticals these days.
      It seems there is evidence that brain activity of various kinds is different in some ways (though there are lots of overlaps) when choices are hypothetical rather than real. There are also differences between realistic and unrealistic visual stimuli. There has been some research into the field. Camerer and Mobbs note that there has been interest in creating ‘ecologically valid’ experiments, something I briefly mentioned here. They’re interested in the ways that real decisions involving future consequences ‘may resemble hypothetical thinking’. In the end they acknowledge the sorts of choices that can’t be made real in an experimental context (e.g. ‘highly rewarding, highly aversive, temporally distant, and morally charged’ ones). And they’re interested in how more realistic methods (e.g. ‘virtual reality, or bidirectional social interactions’) could bridge the gap.
      This whole issue resonates with me: the way the imagination works, what makes things real and/or realistic in the mind, how the act of imagining changes the ways we think and act in the world. These are things that the study of poetics has focused on for millennia. You might say literature has always been the home par excellence of realistic hypotheticals. It’s intriguing to find parallel issues being considered in experimental design. Now — I don’t want to so this again, to do what I so often do, but… there’s no time right now to say more than that.