  We discuss properties of the net baryon number probability distribution near
the chiral phase transition to explore the effect of critical fluctuations. Our
studies are performed within Landau theory, where the coefficients of the
polynomial potential are parametrized, so as to reproduce the mean-field (MF),
the $Z(2)$ and $O(4)$ scaling behaviors of the cumulants of the net baryon
number. We show, that in the critical region, the structure of the probability
distribution changes, dependently on values of the critical exponents. In the
MF approach, as well as in the $Z(2)$ universality class, the contribution of
the singular part of the thermodynamic potential tends to broaden the
distribution. By contrast, in the model with $O(4)$ scaling, the contribution
of the singular part results in a narrower net baryon number probability
distribution with a wide tail.
