A check of the weighting functions proposed by the CIE Technical Committee 1-29 (TC1-29) [Color Res. Appl. 18, 137-139 (1993)] has been carried out using pairs of samples with only a threshold difference in chroma, hue, or lightness. Experimental results with object and aperture colors were used and some parametric factors can be appointed: the dependence of Delta C* on C* appears to be about two times stronger for related color versus the aperture color mode, and the Delta H* dependence on C*, weak but significant for related colors, becomes insignificant for aperture colors. The hue-angle dependences of Delta H* after correction for C* and the dependences of Delta L* on L* or C* are found not significant for aperture colors. After normalization of the five different datasets employed, the results achieved are in overall good agreement and support the proposal of the CIE TC1-29.