An adjustment mechanism for a vehicle seat comprising a support including an annular inner surface, an output member mounted to pivot and including an outer surface, first and second rolling bearing members interposed respectively in first wedge-shaped areas, a driving member having driving fingers designed to push the first and second rolling bearing members, the outer surface including driving portions designed to be pushed by said first and second rolling bearing members respectively in the second and first directions of rotation, the outer surface not having direct contact with the annular inner surface.