376 SECTIONAL TRANSACTIONS.— J. 



of intelligence, and the related problem of a factor of quickness existing 

 independently of intelligence. Previous work shows that the time-limit does 

 not invalidate the measure. On the second question evidence is conflicting, 

 but data are presented showing that such a factor does not exist in any 

 noteworthy amount. 



Division 2. 



Dr. F. W. Edridge-Green, C.B.E. — The relation of the classification of the 

 colour-blind to the tests for colour-blindness. 



The classification of mankind according to the number of colours seen in 

 the spectrum — namely, heptachromic, hexachromic, pentachromic, tetra- 

 chromic, trichromic, dichromic, and absolutely colour-blind — is a very real 

 classification and does not involve any theory. In addition we have those 

 with a defect of light perception — namely, shortening of the red or violet end 

 of the spectrum or defect in light perception of any portion of the spec- 

 trum. These defects are quite distinct from those in which the luminosity 

 curve is normal. For practical purposes we are only concerned with the 

 dichromic and trichromic — namely, those who see two or three colours in the 

 spectrum respectively, and those who have shortening of the red end of the 

 spectrum, preventing them from seeing a red light at the requisite distance. 



A properly constructed lantern and spectrometer are perfectly efficient 

 tests, especially when combined. This applies to all grades of colour vision, 

 even a comparison between the normal and supernormal. 



It is obvious that a man cannot pick out a colour which he cannot see, 

 neither will he be able to recognise the colour of the light when shown in 

 the lantern. 



Mr. W. O'D. Pierce. — Individual differences in colour discrimination. 



The National Institute of Industrial Psychology, at the request of a colour 

 printing firm, undertook the investigation of individual differences in 

 colour discrimination. An account of the preliminary work has been given 

 by Mr. Hudson Davies in British Association Report (1928), p. 606. The 

 colour test described has been given to over 400 individuals ; of whom 147 

 were experienced colour workers, 81 were without colour discrimination 

 experience, and 40 worked under unusual dark room conditions. 



The results on the test show that the experienced workers always give 

 better average results than workers without colour experience. A high 

 correlation was found between the ranking on colour discrimination and 

 results on the test for industrial colour workers. Dark room experience 

 was found to lower the colour discrimination of the worker. Previous 

 training in discrimination was found to aid workers in carrying out the test. 

 The results show that although experienced colour workers do better on the 

 test, the colour discrimination of many of these workers was much lower 

 than the discrimination of the best untrained workers. The workers 

 tested were drawn from the artificial silk, cotton, wool, and colour printing 

 industries. The results obtained show that the test can be used to select 

 workers to meet the varying requirements of these different industries. 



The test indicates the following types of individual colour differences : 

 [a) DiflFerences in total colour discrimination for red, yellow and blue 

 colours ; (6) Differences in the score on each colour series with the same 

 total colour discrimination ; (c) Differences in the variations made on repeti- 

 tion of the test : some subjects improve steadily, other subjects vary 

 without improvement and some subjects give relatively constant scores ; 



