  We report measurements of thermally-induced mean-square director-angle
fluctuations <theta^2> below primary supercritical bifurcations to
electroconvection of the nematic liquid crystals I52 and "Merck Phase V". For
epsilon_mf = V^2/V_c,mf^2 - 1 < -0.1 (V is the amplitude of the applied
alternating voltage) we find <theta^2> proportional to epsilon_mf^(-gamma) with
gamma given by linear theory (LT). Closer to the bifurcation there are
deviations from LT with a smaller gamma and with V_c^2 > V_c,mf^2. For I52
measurements as a function of the conductivity sigma of <theta^2> above V_c^2
suggest a tricritical bifurcation at sigma_t = 4.0 x 10^(-9) Omega^(-1)m^(-1),
and (V_c^2 - V_c,mf^2)/V_c^2 increases strongly as sigma_t is approached from
above.
