The Effect of Object Size on the Performance of Colour Ordering and Discrimination Tasks

Abstract

The effect of object size on the performance of colour ordering and discrimination tasks by a series of 102 colour-defective and 102 age-matched colour-normal observers was investigated using 3 sizes (0.5°, 2.5° and 10°) of the Farnsworth Panels H16 and D15 and Lanthony’s desaturated D15: the Nagel anomaloscope (0.5° and 2°) and large and small samples of coloured fabrics, cotton threads and paints.Colour normals and anomalous trichromats were assisted by an increase in object size for the Panel H16 and D15 tests but not for the desaturated Panel D15. Only three of the subjects diagnosed as anomalous trichromats with the standard Nagel anomaloscope became dichromatic with the small-field (0.5°) anomaloscope and all three were extreme anomals. Protanopes were assisted by an increase in object size for the Panel H16 and D15 tests but not for the desaturated Panel D15. Deuteranopes were not significantly assisted by an increase in object size for any of the panel tests. Both protanopes and deuteranopes made fewer errors naming large coloured objects compared to the small objects. Fourteen percent of the subjects who passed the standard 2.5° size of the Panel H16 failed the 0.5° H16, while 7% of those who failed the standard H16 passed the 10° test. Although several clinical tests showed a significant correlation with the colour naming of large and small objects, there was no discernable association between performance on clinical and colour naming tests of a similar size.KeywordsField SizeColour VisionObject SizePanel TestColour DiscriminationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.