One of my favourite studies in this area was undertaken by Marcel Just at Carnegie Mellon University. Participants drove along a winding road in a rudimentary simulator, controlled via a mouse, while lying in an fMRI scanner to record brain activity. In one condition, participants had to engage in a sentence comprehension task while driving, similar to engaging in a mobile phone conversation. Compared to a control trial, steering behaviour in this “dual-task” condition was much worse, with more frequent collisions with the road edges.