SECTION J.— PSYCHOLOGY. 



TESTS IN COMMON USE FOR THE 

 DIAGNOSIS OF COLOUR DEFECT 



ADDRESS BY 



Dr. MARY COLLINS, 



PRESIDENT OF THE SECTION. 



Tests for colour vision fall into two categories. In the one type of test, 

 transmitted light is used, in the other reflected light. While the former 

 type of test is regarded as the more fundamental, the latter can be of 

 great service for quick diagnosis of colour anomaly. Colour tests may be 

 administered purely for theoretical purposes, or they may be applied for 

 practical purposes, as selection tests for different vocations. This second 

 function assumes its most important role in vocations in which lack of 

 accurate discrimination between different coloured signals may involve 

 human lives. This function is also of significance in other vocations in 

 which the lack of colour discrimination, though not involving danger to 

 the community, is highly disadvantageous to its possessor. 



These two aims, though not mutually exclusive, it is better to keep 

 clearly in mind in any discussion. The results of certain tests may be 

 invaluable for theoretical purposes, although for practical purposes their 

 value may be negligible. This confusion of the two aims has probably 

 been partly responsible for the production of the many differences of 

 opinion which have been expressed with regard to the commoner tests 

 at present used for diagnosis. 



There seems to be no need at the present day to emphasise the im- 

 portance of the recognition and detection of colour defect. It is, however, 

 very illuminating to study some of the more recent investigations in the 

 field, particularly those concerned with the incidence of red-green 

 defect. The percentages given seem to be much higher than in the 

 reports of the earlier investigations. It does not necessarily follow that 

 the incidence of the defect is increasing ; the indications are rather that 

 detection is more accurate owing to the improvement of the test material. 

 The figures given in previous estimates are generally somewhere in the 

 region of 3 or 4 per cent, so far as the male population is concerned. 

 While some of the percentages quoted during the past few years are 

 still in this vicinity, it is not unusual to find a number of considerably 

 higher percentages recorded also. Waaler,^ who tested 9,000 persons, 

 found a frequency of 8- 01 per cent, in the male sex ; Planta ^ testing 



^ See Article by Bruckner. ' Neure Forschungen iiber angeborene Farben- 

 sinnstorungen,' Schweiz. Med. Jahvb., 1932. ^ Ibid. 



