Maps and histograms of toy models with a steep rotation curve (v₀ = 250 km s⁻¹, r_s = 20″ and γ = 2) with a spiral perturbation. We show (top), from left to right, the density map, the velocity field, and the BS corrected dispersion maps in the isotropic and anisotropic cases, obtained with an inclination of 60° and with ϕ_sp = 135°. The bottom panels show amplitude and phase histograms of orders k = 2 and k = 4. Blue and green histograms correspond to the cases with local uniform isotropy with large-scale asymmetries, and local uniform anisotropy with large-scale asymmetries, respectively.