One Task at a Time Doing two things at once impairs performance. In this study, researchers compared the speed of a sensorimotor task (walking) and a cognitive task (naming objects within a category—for example, naming as many colors, spices, insects, crimes, four-legged animals as possible within a minute or two). The participants did each task separately first, and then they did both at once. Performing them both at once resulted in performance losses for everyone. Note, however, that the eldest seemed to safeguard verbal fluency (only a 3 percent slowdown) at the expense of significantly slower walking.