Upper panel: standard deviation σ of the Gaussian distribution fitting for | Δ ν | as a function of the distance to the central galaxy. Middle panel: magnitude difference ( between neighbour i and its corresponding primary CIG galaxy P) for satellites (| Δ ν | ≤ 315 km s^-1, red dashed line) and for background galaxies (315 < | Δ ν | < 3000 km s^-1, red solid line) as a function of the distance to the central CIG galaxy. Lower panel: size ratio ( between neighbour i and its corresponding primary CIG galaxy P) for satellites (| Δ ν | ≤ 315 km s^-1, blue dashed line) and for the background population (315 < | Δ ν | < 3000 km s^-1, blue solid line) as a function of the distance to the central CIG galaxy. The inner 0.3 Mpc are shaded in the three panels.