Daniel Kahneman. Think slowly... Solve quickly (№ 391358)

Another significant discovery is the strong influence of mood on work of intuition. To measure accuracy, the experimenter calculated the "index of intuition". They found that if the experiment is to lead the participants in a good mood thinking positively, the accuracy increases more than twice. Saddened by the participants, by contrast, was utterly unable to cope with the task on intuition; their guesses were no better than random.