The fraction of galaxies with D_n(4000) > 1.5 relative to the control sample, fraction (D_n(4000) > 1.5_(M/T))/fraction (D_n(4000) > 1.5_(Control)), as a function of M_r, for the brightest and the faintest pair members in minor interactions, upper and medium panels respectively. Solid and dashed lines correspond to M and T types, respectively. In the lower panel we show the corresponding distributions for major interactions. The errors shown were calculated within uncertainties derived through the bootstrap re-sampling technique.