Mean radial profiles of the D_n(4000) parameter with respect to R/R_eff for all the galaxies in each merger stage. The radial profiles are represented in different colours for each merger stage according to the legend. Uncertainties are represented in the same colours at 1σ level. The slope, m, of the linear fit to the mean radial profile up to 1.5R/R_eff (marked with a dashed vertical black line), with its corresponding uncertainties, are included in the legend for each merger stage. The number of galaxies in each merger stage is indicated in the lower right-hand corner, with text coloured as denoted in the legend.