First row: time evolution of the radial vertical dispersion profiles, σ_z(r), for the gSb, gSa, and gS0 models. Different colors and line styles correspond to the times indicated in the first row, rightmost panel. The bars’ corotation (CR) and outer 2:1 Lindblad resonance (OLR) are shown by the dotted and solid vertical lines, respectively, with colors corresponding to the different times. Second row: same but for the radial velocity dispersion, σ_r(r). Third row: same but for the ratio σ_z/σ_r. The slope in σ_z/σ_r outside the bar shows that the radial profile flattens more with time than the vertical one, while its overall decrease means that the disc heats more radially than vertically.