1. An apparatus for assisting safe operation of a vehicle, the vehicle having a vehicle environment, the apparatus comprising: an environment sensor system, operable to detect hazards within the vehicle environment and to provide hazard data; a driver monitor, operable to provide driver awareness data, the driver awareness data including a gaze track; and an attention-evaluation module, identifying perceived hazards and unperceived hazards by comparing the hazard data and the gaze track, the attention-evaluation module providing an alert signal relating to the unperceived hazards, the attention-evaluation module including an electronic circuit having a processor, the processor operable to execute an algorithm comparing hazard location data with the gaze track, the algorithm including a model of driver memory, the model of driver memory including a minimum fixation time required for awareness, a memory retention time, and a memory capacity, the electronic circuit being operable to estimate driver awareness using the model of driver memory.