Predictably Irrational: The Hidden Forces that Shape Our Decisions
By Dan Ariely
HarperCollins £14.99, 304 pages
FT bookshop price: £11.99

Not long ago three professors, Daniel Ariely, Elie Ofek and Marco Bertini, set up a stall to hand out free cups of coffee at the Massachusetts Institute of Technology (MIT). In exchange, they asked patrons to tell them whether they liked the roast.