1874 1878
Wilhelm von Bezold ’ s Farbentafel was the first to demonstrate the concept that a colour may appear differently depending on its relationship to adjacent colours .
This is called the Bezold effect .
Instead of seeing complementary colours , Ewald Hering saw opposing colours and concluded that there were in fact not three , but four ( plus white & black ) primary colours coupled in three opponent pairs : red – green , yellow – blue , and white – black . This was the basis of the “ opponent process theory of colour vision ”. Hering called these six colours the “ psychological primaries ”.