The MRI scans showed that a brain network that governs how much pain people feel became active even before they were shocked, particularly the parts of this "pain matrix" that are linked to attention - but not brain regions involving fear and anxiety. The more dread bothered someone, the more attention the pain-sensing parts of the brain were paying to the wait.

In other words, the mere information that you're about to feel pain "seems to be a source of misery," George Lowenstein, a specialist in economics and psychology at Carnegie Mellon University, wrote in an accompanying review of the work.

"These findings support the idea that the decision to delay or expedite an outcome depends critically on how a person feels while waiting," Lowenstein added.