A new neuroimaging study on stressed-out students suggests that male humans, like male rats, don’t do their most agile thinking under stress. The findings, published this month in the Proceedings of the National Academy of Sciences, show that 20 male M.D. candidates in the middle of preparing for their board exams had a harder time shifting their attention from one task to another than other healthy young men who were not in similarly stressful situations. Luckily, when the stressful situation no longer exited, their attention-shifting performance and brains returned to normal.