Neuroscientist Scott Huettel of Duke University in Durham, North Carolina, isn’t convinced of the two-task limit on human multitasking ability. “This shows there are conditions in which you can’t add a third task, but it depends on the type of task and whether it draws on other parts of the brain,” he says.
For example, people are remarkably good at eating while doing other things, he says, because the practiced motor skills involved in eating don’t overlap too heavily with those that interpret visual cues, control language, or run other complex processes. Nevertheless, he finds the dual-task division of labor “novel and exciting.” The study illustrates our striking lack of knowledge about how the brain’s hemispheres organize themselves, he says. “I wouldn’t have bet multitasking worked this way.