	Guinness cited vos Savant's performance on two intelligence tests, the Stanford-Binet and the Mega Test. She took the 1937 Stanford-Binet, Second Revision test at age ten. She claims her first test was in September 1956 and measured her mental age at 22 years and 10 months, yielding a 228 score. This figure was listed in the "Guinness Book of World Records"; it is also listed in her books' biographical sections and was given by her in interviews.