Later , others tried to improve on his theories with systems such as characterology .
The misuse of Gall 's ideas and work to justify discrimination were deliberately furthered by his associates , including Johann Spurzheim .
Later , others tried to improve on Gall 's theories with systems such as characterology .
The misuse of Gall 's ideas and work to justify discrimination were deliberately furthered by his associates , including Johann Spurzheim .