Don’t talk and drive
by It will fluctuate
This New York Times article lead me to two meta-analyses (here and here) which found that there are significant risks to talking while driving, which “appear to be manifested primarily in measures of response time to critical road hazard or stimuli”. “[D]rivers responded about 1/4 of a second later to stimuli in the presence of a cell phone distractor for all studies that were analyzed”, and that number “probably underestimates the behaviour of drivers when not being observed”.
And “hands-free cell phones do not eliminate or substantially reduce those costs”.
I listen to audio books while driving. There is not much research on that, but this study suggests it might not be a good idea either: “In-vehicle activities such as listening to the radio (1.21) or an audio book (1.75) were associated with a small increase in cognitive distraction, the conversation activities of talking to a passenger in the vehicle (2.33) or conversing with a friend on a hand-held (2.45) or hands-free cell phone (2.27) were associated with a moderate increase in cognitive distraction,and the speech-to-text condition (3.06) had a large cognitive distraction rating”.