Operator complacency increases with time spent in a partially automated vehicle and reduces the ability and accuracy of detecting hazards. Drivers are expected to monitor for signs of automation failure, but past research has shown a decline in the ability to perform this duty 
Drivers often fail to spot hazards missed by automated vehicles. Source: Rice Universityover time.
To determine how often dangerous situations missed by automated vehicles also go unnoticed by operators, researchers from Rice University and Texas Tech University monitored the actions of 60 drivers in a simulated, partially automated vehicle. After being told that they need not operate the brake, the accelerator and the steering wheel, participants completed a 40-minute-long drive, during which they monitored for hazards that represented potential automation failures.
Operator accuracy declined 7% to 21% percent during the test. Most drivers failed to observe vehicles stopped dangerously at intersections and intruding into the driver’s lane, which constituted a hazard that automated vehicles could not detect.
Safe operation is less likely as drivers experience high workloads and task-induced stress, indicating that automation technology engineers should consider countermeasures that attenuate a driver’s cognitive load when tasked with monitoring automation.
