A seat comprises a base assembly adapted to be fixed to the body of the vehicle, an articulated support assembly comprising front and rear support links for a seat cushion of the seat each of which has two ends articulated about axes which are respectively fixed relative to the seat cushion and to the base assembly, devices for adjusting the angular position of the support links relative to the seat cushion, and devices for controlling the position of a seat back of the seat relative to the seat cushion. The control devices comprise a convex or concave articulated quadrilateral, which has four corners, a first corner is connected to the seat cushion and the second and fourth corners are connected to the seat back.