SF efficiency as a function of the velocity dispersion of the regions (σ_v, regions) across the merger sequence. From left to right and top to bottom, the merger stages are: isolated galaxies (blue), galaxy pairs (red), early-stage mergers (orange), mid-stage mergers (magenta) and late-stage mergers (black). The Spearman’s rank correlation coefficients (ρ_s) are indicated. The bottom right panel shows the mean values of σ_v, regions and log₁₀SFE_regions, with error bars representing the mean absolute deviation for each merger stage.