A Simple Psychological Explanation

The following results may surprise you.

As a matter of fact, they are very natural.

Let me explain how to measure the personality psychologically.

Many psychological personality tests are based on the simple principle that person's personality can be measured by "self-report" of "words" that express his or her personality (or characters, rather).


Example:  Are you nervous?


You shall answer between 1 point (strongly disagree) and 5 points (strongly agree) to such questions.

Note that nearly 70% of Japanese (or Korean, Taiwanese ...) people feel that blood types and personality are related!

Q Blood types and personality are

A: Feel like related

B: Not related


Source: A Japan's TV Show
"Serious Issues of Japan" (日本のダイモンダイ) broadcast on November 8, 2015

Number of respondents: 201, 119 people


This literally means that each person's "self-report" of "words" are different according to their blood types. Then, theoretically, it is possible to measure differences in personality by blood types - psychologically.  Because denying this conclusion is denying psychology itself ...


The next is an explanations by Japanese psychologists.


Results of self-report-type questionnaires are usually considered as "personality itself" (not only "recognition of self's personality").

Source: Toshinori Shirasa & Takuji Iguchi, An Introduction to blood-type personality research (1993) 白佐俊憲・井口拓自 血液型性格研究入門―血液型と性格は関係ないと言えるか


Also a famous psychologist, H. J. Eysenck said on astrology in his book. 


Prior knowledge [of sun signs or zodiac] does influence the subject into seeing his own personality in conformity with what astrology tells him to expect.

Source: H. J. Eysenck, Astrology: Science or Superstition? (1982)


This must be the same with blood type.

After all, thinking logically, differences of personality by blood types exist universally rather than rarely, at least in Japan (also Korea and Taiwan). The same things must have happened in many questionnaire surveys on personality. Why have no one ever noticed such a simple thing, until now?


For further information, please visit my website. 

Other Japanese Surveys

For almost three decades, more than 70% of Japanese people think that there likely are "relationship between blood types and personality" and the ratios are much the same.

However, less than 20% of people think that there is strong relation, while a little less than 50% of people think that there is some relation. These data completely agree with my inference! 
Namely, there is not strong relationship between "blood types and personality", but some relation.


1. Do you think that there likely is relationship between blood types and personality?
  -- 1,102 Tokyo metropolitan residents aged 15 - 69 by random sampling




Yes 75.0%
No 18.4%
D/K 5.9%
N/A 0.6%

from NHK (Japan Broadcasting Corpration) public opinions research (1986)


2. Do you think that there is relationship between blood types and personality?
  -- 2,320 men and women all around the nation residents aged more then 20




Yes 18%
More and less 46%
No 21%
D/K 14%



from the Mainichi Newspaper "Kokoro no Jidai [Times of Heart]" (1987)

Nation-wide research


3. Is there relationship between blood types and personality/compatibility?

  ---500 people




Yes 72%
No 18%
D/N 10%

from Kansai TV's "Aruaru Daijiten" (June 15, 1997) 

A Survey in Korea

According to a website "WoW! Korea," three quarters Koreans believe in close relationships.


<W column> Koreans love "blood type-specific personality", No O in "B1A4"

Korea is now more sensitive to "blood type-specific personality" than Japan, and 75% of Koreans believe in the close relationship with blood types and personality.



(July 21,2014)

A Survey in Taiwan

According to a survey conducted in Taiwan, the ratio of persons who have read books about blood types is as high as 75%, and the ratio of having the belief is 66%.

We may think that the situation is almost similar to Japan.



Kunher Wu, Kristian D. Lindsted, Jerry W. Lee

Blood type and the five factors of personality in Asia

Personality and Individual Differences 38 (2005) 797–808


After obtaining permission from the city of Kaohsiung in March 2000 to conduct surveys in all of their 29 high schools, we used stratified random sampling to select participating classes from each school. We initially contacted 3844 11th grade students. We recruited students from the 11th grade because, unlike seniors, they would not be studying for the college entrance exam, and would still meet the age requirement for administering the NEO-PI-R questionnaire (age 16 years or older). Nearly 90% of potential participants (N=3444) returned signed consent forms and were given the questionnaire. 


Table 1 Distribution of gender, blood type, books, belief, and language separated by academic achievement level [abbreviated]


Males 1497
Females 1899
Type A 651
Type B 610
Type O 1282
Type AB 138
Books b
  Yes 2489
  No 851
Belief c
  Yes 2175
  No 1137
Language d
  Mandarin 1765
  Taiwanese 1529


a Based on school enrollment, which depended on students' national test scores. 

b Reponses to "Have you read any books about blood type and personality?"

c Reponses to "Do you believe there is a relationship between blood type and personality?"

d Language spoken at home.


For further information, visit my website.