Experimental data for a paper titled "Invariant categorical color regions across illuminant change coincide with focal colors“ published in Journal of Vision. This repository contains following data. Please refer to the article for details about the dataset. 1. IlluminantsANDReflectances.xlsx This file stores spectral radiance for each illuminant and OSA coordinates (jgL) and reflectance values for 424 OSA color samples. 2. Exp1_1_RawData Raw data for Experiment 1-1. This folder has xlsx files, and filename indicates the illuminant condiion. In each xlsx file, different sheets contain a different observer’s data. The number (1-424) corresponds to the number of OSA sample (shown in IlluminantsANDReflectances.xlsx). 3. Exp1_2_RawData Raw data for Experiment 1-2. The same format as Exp1_1_RawData. 4. Exp2_RawData.xlsx Raw matching data for Experiment 2. The name of each sheet shows the observer & illuminant condition. Each row shows Ljg coordinates of the OSA sample and associated matching result (in RGB and xyL).