Dr Max Luscher developed the Luscher Color Test in 1969 with the intention to measure a person’s psychological state: based on their colour preference along with his or her ability to withstand stress, to perform, and to communicate.
Using 5015 definitions, the selections from the pre-determined test colours are supposed to be able to measure the state of 24 personality traits, some of which lie “outside of the realm of the conscious”.
Luscher wrote that:
The Luscher Color Test, despite the remarkable ease and speed with which it can be administered, is a ‘deep’ psychological test, developed for the use of psychiatrists, psychologists, physicians and those who are professionally involved with the conscious and unconscious characteristics and motivations of others.
While you can’t take the full official test online, there is a short version you can try to get an idea of how the test works.