OBJECTIVE:

In this study, we investigated how drivers adapt secondary-task initiation and time-sharing behavior when faced with fluctuating driving demands.

BACKGROUND:

Reading text while driving is particularly detrimental; however, in real-world driving, drivers actively decide when to perform the task.

METHOD:

In a test track experiment, participants were free to decide when to read messages while driving along a straight road consisting of an area with increased driving demands (demand zone) followed by an area with low demands. A message was made available shortly before the vehicle entered the demand zone. We manipulated the type of driving demands (baseline, narrow lane, pace clock, combined), message format (no message, paragraph, parsed), and the distance from the demand zone when the message was available (near, far).

RESULTS:

In all conditions, drivers started reading messages (drivers' first glance to the display) before entering or before leaving the demand zone but tended to wait longer when faced with increased driving demands. While reading messages, drivers looked more or less off road, depending on types of driving demands.

CONCLUSIONS:

For task initiation, drivers avoid transitions from low to high demands; however, they are not discouraged when driving demands are already elevated. Drivers adjust time-sharing behavior according to driving demands while performing secondary tasks. Nonetheless, such adjustment may be less effective when total demands are high.

APPLICATION:

This study helps us to understand a driver's role as an active controller in the context of distracted driving and provides insights for developing distraction interventions.

© 2014, Human Factors and Ergonomics Society.