These results indicated that Japanese blood-typical stereotypes actually influenced their self-reported personalities—as a self-fulfilling prophecy. (Nagasaki University) conducted a supplementary survey of Yamazaki and Sakamoto in 2011.
However, some academic researchers have shown several statistically significant data in Japan and Korea.
Akira Sakamoto and Kenji Yamazaki, Japanese social psychologists, analyzed 32,347 samples of annual opinion polls from 1978 through 1988.
However, 65 of the 68 items yielded non-significant differences between blood types and the other three items showed relatively slight relationships.
Therefore, the blood type explained only 0.3% of the whole differences of these data sets.
The popular belief originates with publications by Masahiko Nomi in the 1970s.