Color Constancy for Three-Dimensional Objects
Experiment 1, Excluded Subject FJK
Subjec FJK completed the entire experiment. This subject's early experimental sessions were well-behaved and generally met our inclusion criteria. The subjects later sessions, however, consistently failed to meet our criteria. We suspect that this subject simply stopped paying attention at some point during the course of the experiments, although this is only a conjecture. In all, 11 experimental sessions for this subject met our inclusion criteria, while 34 did not; none of the last 30 experimental sessions run by this subject met the criteria. To provide a sense of the issue, these three staircase trajectory plots (example1, example2, example3) show data from three sessions from FJK for the same condition. The data for the first session are sensible; those from the latter two are difficult to interpret.
To extract some information from FJK's sessions, we relaxed the standard deviation threshold of our inclusion criteria to 0.03 (rather than 0.02). This provided data from one experimental session for all but one of our conditions (matte sphere, Yellow illuminant, normal background). The data below provide the results. Because this observer's data are suspect because of the degradation in data quality over the course of the experiment and because we have only one session per condition even with relaxed inclusion criteria, we did not average this observer's data in with that of the other observers. The constancy index data for FJK are consistent with the average data from Experiment 1, with the exception that the constancy index for the matte disk in the Blue illuminant/normal background condition is low. The value for this index depends on data from the Neutral illuminant/normal background condition, which just barely met our relaxed inclusion criteria (standard deviation across staircases 0.29, staircase trajectory plot here). We do not place much weight on this datum.
Session summary data file (tab delimted text). See summary file format page for infomation on what is in this file.
Condition summary data file (tab delimited text). See summary file format page for infomation on what is in this file.
Achromatic points (pdf plot). The figure shows the achromatic points in the uv chromaticity diagram. Solid circles show data for the normal backgrounds, open circles show data for the equated backgrounds. Where visible, error bars show +/- one standard error. Crosses show illuminant chromaticities. Within each panel the color code is: Neutral illum -> black; Blue illum -> blue; Yellow illum -> red. Each panel is for one test object: Matte disk -> left; Matte sphere -> center; Glossy sphere: right. The solid yellow circle in the center and right panels replots the Neutral illuminant achromatic point for the disk. There is no plotted point for the matte sphere in the Yellow illuminant/normal background condition because data were not available (see above).
Constancy indices (pdf plot). The figure shows the constancy indices for each test object. Labels: Blue illuminant/normal background -> Blue; Yellow illuminant/normal background -> Yellow; Blue illuminant/equated background -> Eq Blue; Yellow illuminant/equated background -> Eq Yellow. There is no index for the matte sphere in the Yellow illuminant/normal background condition because data were not available (see above). There is an index for the matte disk in the Yellow illuminant/equated background condition but it is difficult to see in the plot because it is very close to zero.