For the experiment which is to be explained further in the paper used samples were of eight, differently coloured sheets of paper, size A4 (a total of 1548 sheets) and white and black sheets, as background, size A0. For the defining of colourmetrical values of the above mentioned samples and backgrounds the "Graphic CIE L*a*b* Calculator" was used. A total of 99 examinees have visually defined the centre of the coloured samples both on white and black backgrounds by classic observation (a total of 16 definintions by an examinee).
The deviaton of optical from the geometrical centre of the sheet has been measured. The results obtained helped to measure the colourmetrical values of the samples as well as to examine and define the correlation between the deviation of optical from the geometrical centres of the samples observed on white and black backgrounds. Based on the results obtained a conclusion can be drawn that the colour of the observed object is conditioned by a perception of the same.