It is clear that the full automorphism group of the (15, 8, 4) -design of points and hyperplane complements of PG (3, 2) is GL (4, 2). Using methods of point-line geometries, we determine the full automorphism groups of the remaining four symmetric (15, 8, 4) -designs and describe their actions on the sets of points and blocks.
Pankov et al. (Fri,) studied this question.