*Luminance*

In [20], it was observed that one of the reasons why some colors seemed nearer than others was luminance difference, with bright objects appearing closer than dim ones. This would support the claim that "warm colors tend to advance and cool colors recede" since warm colors tend to be brighter than cool colors. In the following Figure 14, and Tables 12 and 13, the same color can be seen next to each other with different luminance levels. In both cases, the high luminance version of the color seems to be nearer than the dark color.

**Table 12.** Temperature-depth mapping of the left side of Figure 14. Even though both colors were visually similar and the depth difference conveyed was not too large, the extreme temperatures of 14ºC and 38ºC were selected but since there are only two depth levels, other temperature difference could have been used, but with the brighter color being warmer.




**Figure 14.** Higher luminance colors tend to be seen as been nearer than low luminance ones.
