Abstract: The device includes a stereoscopic image recording device having at least one optical sensor which records the scene at the vehicle seat and derives from that a three-dimensional map, partitioned into a plurality of zones, giving for each zone its distance from a reference point. In order to make possible reliable recognition of the manner of the seat's occupation, even during great fluctuations of light intensity, the at least one optical sensor has a nonlinear characteristic curve, describing the correlation between the incident light intensity and its electrical output signal, whose characteristic curve steepness decreases with increasing light intensity.