Embodiments of the present invention provide a control system for a vehicle, the vehicle (800) being operable in an at least partly autonomous mode and a manual mode, the control system comprising input means (291, 292) for receiving a gaze signal (211) indicative of a direction of a gaze of an occupant of the vehicle (800), and a contact signal (212) indicative of physical contact between the occupant and a control of the vehicle, control means (250, 260, 270, 280, 290) configured to determine an estimate of the occupant's attention to a driving task in the at least partly autonomous mode in dependence on the gaze signal (211) and to determine when the occupant is at least partly obscured relative to the at least one imaging means (150, 220), wherein the control means (250, 260, 270, 280, 290) is configured to determine the estimate of the occupant's attention to the driving task in dependence on the contact signal when it is determined that the occupant is at least partly obscured.