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Marilyn vos Savant was added to the Guinness Book of World Records in 1986 for the highest recorded IQ, holding the title until the category was retired in 1990. The number cited - 228 - came from a Stanford-Binet test administered when she was 10 years old. As an adult she also took the Mega Test, a high-ceiling instrument designed by Ronald Hoeflin, and recorded one of its highest scores.

She has written the "Ask Marilyn" column in Parade Magazine since 1986, where she famously answered the Monty Hall problem in 1990 - and was attacked by hundreds of mathematicians for an answer that was, on review, correct. The episode became a famous case study in mathematical intuition.

The 228 figure is contested by psychometricians for two reasons. First, the childhood ratio-IQ formula (mental age ÷ chronological age × 100) can produce extreme values that do not translate cleanly to adult deviation IQ scales. Second, the Mega Test does not have the standardization sample needed to produce confidence intervals at that range. Vos Savant herself has been measured publicly and has commented thoughtfully on the limits of any single number.