  Motivated by the experimental search for the QCD critical point we perform
simulations of a stochastic field theory with purely relaxational dynamics
(model A). We verify the expected dynamic scaling of correlation functions.
Using a finite size scaling analysis we obtain the dynamic critical exponent
$z=2.026(56)$. We investigate time dependent correlation functions of higher
moments $M^n(t)$ of the order parameter $M(t)$ for $n=1,2,3,4$. We obtain
dynamic scaling with the same critical exponent $z$ for all $n$, but the
relaxation constant depends on $n$. We also study the relaxation of $M^n(t)$
after a quench, where the simulation is initialized in the high temperature
phase, and the dynamics is studied at the critical temperature $T_c$. We find
that the evolution does not follow simple scaling with the dynamic exponent
$z$, and that it involves an early time rise followed by late stage relaxation.
