2IO 



UNIVERSITY OF COLORADO STUDIES 



Experiments on Adults 



The problem of this investigation was twofold: to measure sex 

 differences and to determine the variability and range in color perception. 

 The study was made primarily to secure evidence on variability. 



The method employed was as follows: A series of fifty reds was 

 prepared by mixing the best English vermilion and chrome yellow 

 pigments with gum arabic. For the first color a mixture of forty grams 

 of vermilion was made and painted on an eggshell card board, 6X6 

 inches. For each succeeding step in the series one-fourth of a gram 

 of chrome yellow was added to the mixture and similar cards prepared. 

 The result was a very satisfactory color series, covering purposely a 

 small range, with a view to eliminating in the test, so far as possible, 

 the factor of brightness. * 



For the purpose of determining the correlation between discrimina- 

 tiveness to light and color a series of fifty grays, ranging from the white 

 of the paper used to a mean gray, was also prepared. 



From the colors and grays obtained, squares 3X3 inches were 

 mounted on playing cards, cut so that the colors or grays might in the 

 experiment be placed side by side. Thirty-five men and thirty-five 

 women students were asked to make the arrangements. Forty-five 

 minutes were given for the reds and fifteen minutes for the grays. The 

 tests were taken in a room with a north exposure giving a uniform light. 



The method of calculating the results consisted in determining the 

 average of the errors made in placing each of the colors, an error of one 

 place counting one, two places two, etc. The average error of displace- 

 ment, the mean variation, coefficient of variation and the median of 

 displacement are indicated in the tollowing table. 



1 It had been my plan to make similar series of blues, greens and yellows, but the difficulty of preparing 

 satisfactory series with mineral pigments led to its abandonment after numerous fruitless trials. 



