Katie Corker wondered what temperature the coffee was supposed to be. She was doing a psychology experiment—well, redoing an experiment. The original findings, suggesting that holding something warm can make a person behave warmly, had been published in 2008 in the prestigious journal Science to a flurry of media coverage. Yet as Corker tried to retrace each step in the study, there were so many unknowns: the temperature of the hot coffee distributed to subjects, how quickly the mug cooled in their hands.