Dr. Richard Young, professor of Psychiatry and Behavioral Neurosciences of Wayne State University School of Medicine spoke at the MIT AgeLab about his research on Cell Phone Conversations, Drowsy Driving and Automobile Crashes.
Abstract: The aim of research into cell phone tasks is to obtain an unbiased estimate of their relative risk (RR) for crashes. This paper re-examines five RR estimates of cellular conversation in automobiles. The Toronto and Australian studies estimated an RR near 4, but used subjective recall to estimate driving times. The OnStar, 100-Car, and a recent naturalistic study used objective measures of driving times and estimated an RR near 1, not 4 – a major discrepancy. Analysis of data from GPS trip studies shows that subjects were in-car only 20% of the time on a previous day, given they were in-car at the same clock time on a subsequent day. Hence, the Toronto estimate of driving time during control windows must be reduced from 10 to 2 min. Given a cell phone call rate about 7 times higher when in-car than out-of-car, and correcting for misclassification of some post-crash calls as pre-crash, the Toronto adjusted RR is 0.61, and the Australian 0.64, agreeing with the OnStar estimate of 0.62. After adjustment for bias, all five RR estimates for cellular conversation while driving in automobiles are near 1, with a pooled RR of 0.61 (95% confidence interval 0.51 to 0.74).
A recent study found that drowsy driving prevalence in U.S. national crash databases is substantially higher than previously estimated, especially for fatal crashes. The aims of the current study are to merge this result with a new estimate of the prevalence and odds ratio (OR) of drowsy driving in the 100-Car naturalistic driving study (NDS), and investigate interactions with secondary tasks, particularly cell phone conversation. A 2010 NDS study matched baseline video clips to crash/near-crash video clips for driver demographics, time of day, and GPS location. Using that matched baseline to remove bias from those variables, the current study estimates the drowsy driving OR for crashes to be 63, substantially higher than previous estimates. In addition, observable moderate to severe drowsiness causes an estimated 20% of all crashes, while non-observable microsleeps likely elevate that percentage. A logistic regression analysis on the 100-Car data found no interaction between drowsy driving and secondary tasks as a whole. However, the moderately-difficult task group (which includes cell phone conversation) reduced the drowsy driving crash/near-crash OR, as did cell phone conversation alone. These new NDS analyses provide preliminary evidence that curtailing drowsy driving will reduce more crashes than curtailing secondary tasks while driving.