Route familiarity breeds inattention and cell-phone adds to it

Many traffic accidents occur because of inattention. We hypothesized that familiarity with a route may lead the driver to pay less attention to details in the environment. To examine this hypothesis, we tested two groups of participants in a high-fidelity driving simulator. In an initial training session, one group was familiarized with Route A, the other with Route B. In the test session, both groups drove through Route A, thereby making one group familiar and the other unfamiliar with the route. Sudden events (car pulling out, people running onto the road) were presented during the test session, and reaction times (RTs) to activate the brakes in response to those events were recorded. RTs were significantly slower in the Familiar group, consistent with the hypothesis that familiarity leads to inattention. Further, we investigated how the familiarity-based inattention interacts with divided attention due to cell-phone use.