Although the CIE1931 and 1964 color matching functions have been used in color specification for decades. man v researchers, from Allen in 1970 to Hit and Houser in 2006, have found that there still exists a great visual mismatch on the discrimination of color difference as in terms of the CIE color matching functions. Hence, some significant error would be made on color specification due to employing the CIE1931 and 1964 color matching functions. Therefore, six color difference formulae developed from different experimental methods are used to derive various deviate visual functions (DVFs) respectively, and to investigate the effect of these DVFs on the performance of the color difference formulae tested in estimating visual color difference. The results indicate that the performance of the color difference formulae in estimating color difference is significantly improved by the deviate visual functions derived in this study. The CIE94 color difference formula has the best performance in predicting the total visual color difference (triangle V-T) using the DVFs and DVFIIs having the mean values 29 and 27 in PF14 unit, respectively, while the CMC(l:c) the worst the ones 37 and 38. (c) 2009 Wiley Periodicals, Inc. Cot Res Appl, 34 115-127, 2009: Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20482