Progress report on color rendition studies: insights into how light sources alter perceived color . This edition presents findings from a 1956 study on color rendition, showing how observers compare color under different lamps and how calculations align with what people see. This material explains how researchers test color perception using Munsell samples under three lamp types, and how they map observations to computed results. It highlights the challenges of achieving consistent color judgments across sources and the ongoing effort to develop a reliable method for measuring color rendition. Experiments compare chromaticness, hue, and saturation ratings of 18 color samples under multiple light sources. Data include observer judgments, box setups, and spectral distributions of lamps used in the tests. The text discusses transforming and aligning observed results with colorimetric computations and diagrams. Ideal for readers of scientific color studies and lighting research who want a concrete look at how color perception is tested and analyzed.