Fig. 2.

Adjustments in the dress and in the colour constancy experiments. Adjustments are represented in CIELUV space, with the x- and y-axes referring to u^* and v^*. In all panels the red line corresponds to the first principal component that represents the main variation in the data. Panel a shows individual adjustments of the body (blue dots) and the lace (brown dots) of the dress for all 31 observers in Witzel et al. (2017). The coloured curve indicates the daylight locus. Panels b-c show asymmetric matches for two examples: orange-yellow when adjusting the colour under the blue illumination (panel b, Y2B = yellow to blue; cf. Fig. 1) and purple-blue when adjusting the colour under the yellow illumination (panel c, B2Y = blue to yellow). The black disk indicates the colour signal under the first illumination, the green disk indicates the colour under the second (bluish) illumination, assuming that the colours correspond to a typical natural surface (see text for details). White disks refer to average adjustments of each of the 20 participants in Witzel, van Alphen, et al. (2016), and the large white star indicates the grand average across participants.