  We observe and study new non-linear global space-time symmetries of the full
ghost+matter action of RNS superstring theory. We show that these surprising
new symmetries are generated by the special worldsheet currents (vertex
operators) of RNS superstring theory, violating the equivalence of
superconformal ghost pictures. We review the questions of BRST invariance and
non-triviality of picture-dependent vertex operators and show their relation to
hidden space-time symmetries and hidden space-time dimensions. In particular,
we relate the space-time transformations, induced by the picture-dependent
currents, to the symmetries observed in the 2T physics approach.
