Method for determining driving task demand based on speed variability

A system and method of assessing the driving task demand on the driver of a vehicle (10), and further controlling one or more devices (36) on the vehicle (10) as a function of the assessed driver demand is provided. The method includes sensing a coverage zone (14) in relation to a vehicle (10), determining a presence of one or more objects in the sensed zone (14), measuring speed (R & ) of each detected object in the sensed zone (14), determining a variation in speed of one or more sensed objects, and determining a driving task demand signal (Demand j ) indicative of driving task demand of the vehicle (10) as a function of the measured speed variability. The method controls one or more devices (36) on the vehicle (10) based on the driving task demand signal (Demand j ). Alternately, the driving task demand signal (Demand j ) is determined based on vehicle speed (V h ).