“…Examples include colour hue and colour value (a term under which we subsume value, lightness and brightness) (e.g. Aerts et al, 2003;Edwards and Nelson, 2001;Leitner and Buttenfield, 2000;MacEachren et al, 1998;Nadav-Greenberg et al, 2008;Retchless, 2012;Schweizer and Goodchild, 1992;Slocum et al, 2003), transparency (e.g. Drecki, 2002;Newman and Lee, 2004;Slocum et al, 2003;Viard et al, 2011), or colour saturation that is used in a number of studies (e.g.…”