Prof. Sakamoto


28.gif (298 バイト)Prof. Samamoto's Papers

Mr. Sakamoto (Prof. of Ochanomizu Univ.) kindly sent me several papers.  Great thanks!

In 2011, Mr. Masahiro Nagashima (National Nagasaki Univ.) had performed a supplementary examination of the two Mr. Sakamoto's papers, which is mentioned the bottom of this page.

12.gif (321 バイト)The First Paper

As far as I know, the following paper analyzed the largest number of samples: more than 30,000 people using the random sampling method. Of course, it showed the clear difference between blood types.  But Mr. Sakamoto said "blood-typical stereotypes" caused the difference, not blood types themselves. So he thinks there is no relation between blood types and personality.

Yamazaki, K., & Sakamoto, A. (1992).  Ketsueki gata sutereotaipu ni yoru jiko joju gensho 2 [The self-fulfillment phenomenon generated by blood-typical personality stereotypes: time-series analysis of nation-wide survey 2]. Paper presented at the 33rd annual convention of the Japanese society of social psychology. Tokyo (pp. 342-345).

JNN Data Bank (Japan News Network Data Bank, a department of TBS, which is one of the major TV stations in Tokyo) conducts a large annual survey. Its subjects are about 3,000 people annually, from age 13 to 59 using the random sampling method. The surveys of 1978 - 88 have items of blood type and 24 yes-no questions of personality.

24 yes-no question items of personality

1    I am ready to keep company with everyone.
2    I make an effort toward my goal.
3    I like to be a leader.
4    I am not particular about things.
5    I do not know how to refresh myself.
6    I am serious when I should be so.
7    I often tell jokes to make others laugh.
8    I do not change my idea after I present it.
9    I am not worried by what I was told.
10    I have a lot of friends.
11    I am often worried about things.
12    I sometimes indulge in fancies.
13    I am not good at getting along with others.
14    I like to have parties in my home.
15    I am careful when doing something.
16    I am often moved to tears.
17    I often change my mind.
18    I am a good loser.
19    I am persevering.
20    I cannot be quiet and I make merry when I am delighted.
21    I am shy.
22    I sometimes burst into a rage.
23    I like to think deeply alone more than to talk with others.
24    I do not like to visit someone without presents.

How to calculate each blood-type scores (Type-A score as an example) :

Choose three items that "fit to Type A personality" in red). If people answered "yes" to them and give 100 for each. Calculate the mean value of these three. Also choose three items that "don't fit to Type A personality" (in blue). If people answered "yes" to them and give -100 for each. Calculate mean value of those three, too. Finally take the difference of the two mean values. This is the Type-A score, as we called,  that represents "Type A personality".
Calculate Type-B, Type-O and Type-AB scores using the same method.

As a result: (In the order of  Type A, B, O and AB)

tokuten.gif (107062 バイト)

Mr. Sakamoto also conducted mutiple regression analysis:

As a study:

The rating of Type-A people turned to the stereotyped direction of women's college students. So, there is the possibility that the self-fulfillment phenomenon generated by blood-typical stereotypes is occurring, if there is not the difference of personality between blood types, which is usually said.
Yet, such phenomenon is not detected except Type A. Further surveys will be needed.

12.gif (321 バイト)The Second Paper

The data of this paper is the same as the first paper. But, he did not conduct multiple regression analysis because it was announced one year ago. It is intereting that A-B score of age and sex were calculated (yet, the range of value is between -1 to 1, because it is not multiplied by 100, as the first paper is). I quote the conclusion a little bit.

Yamazaki, K., & Sakamoto, A. (1991).  Ketsueki gata sutereotaipu ni yoru jiko joju gensho [The self-fulfillment phenomenon generated by blood-typical personality stereotypes: time-series analysis of nation-wide survey]. Paper presented at the 32nd annual convention of the Japanese society of social psychology. Tokyo (pp. 289-291).


1. Age / Fig. 5

"A-B" score becomes higher as age becomes higher. In other words, senior people are more like "Type A".

2. Blood type / Fig. 6

"A-B" score of Type-A people (0.082) is significantly higher than that of Type-B people (0.027).

3. Year of the survey / Fig. 7

"A-B" score has gradually decreased in 11 years from 1978 through 1988. In other words, Japanese people are becoming more like "Type B".

4. Alternate action between blood types and year of the survey / Fig. 8

The alternate action between blood types and year of survey were detected. Type-A people become more like "Type A" and Type-B people become more like "Type B". This is the result that means the self-fulfillment phenomenon generated by blood-typical stereotypes.

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12.gif (321 バイト)But...

But, when you carefully watch Fig. 7 of the second paper, you should notice something strange.
Until now, many opponents of "blood type and personality" (especially, Japanese psychologists) have asserted that the difference of personality by blood types does not exist, because reliable data and/or results of questionnaire are not available.
However, the difference is very significant -- out of question -- in Fig. 7 of the second paper. Eleven years and more than 30,000 people by complete random sampling. Therefore, the former assertion, "reliable data and/or results of questionnaire are not available", is completely wrong!
Also read Ms. Yoriko Watanabe's paper.

Watanabe, Y. (1994). The roles of prototype and exemplar in the formation of the "blood type stereotype". Shakai shinrigaku kenkyu [Social psychology research], 10-2, 77-86.

Articles above are updated on May 27, 1998.

12.gif (321 バイト)The Third Paper

When I read the article of Scientific American's guest blog last year (Feb. 15, 2011) --  You are what you bleed: In Japan and other east Asian countries some believe blood type dictates personality -- I found Mr. Sakamoto's paper (he is a very friendly person).

To my surprise, he clearly said that there are definite relationships between blood types and "self-reported" personality.

Sakamoto, A., & Yamazaki, K. et al. (2004), Blood-typical personality stereotypes and self-fulfilling prophecy: A natural experiment with time-series data of 1978-1988, Progress in Asian Social Psychology, Vol. 4. Seoul, Korea, Pp. 239-262. (pdf)
This indicates that blood-typical personality stereotypes actually influenced the personalities - self-reported personalities, at least - of individuals, and that they also operated as a self-fulfilling prophecy, although the greatness of that influence could be discussed.

Would not it become a hot topic in Japan because this paper was an English one?
If I read this article before, I did not have a hard time.
Anyway, the debate -- whether or not there is a statistical difference -- was already over!!

(October 11, 2015)

12.gif (321 バイト)Mr. Nagashima's Research Report

In 2011, Mr. Masahiro Nagashima (National Nagasaki Univ.) had performed a supplementary examination of the two Mr. Sakamoto's papers mentioned above.

The number of samples was 30,000 people in 11 years in Mr. Sakamoto's papers, to my surprise, as many as 200,000 people in 30 years are investigated by Mr. Nagashima's Grant-in-Aid for Scientific Research in 2011.  However, the number of samples and years and were not specified in this report for some reason, so that  I have to suppose these numbers.  The followings are excerpts:

We also demonstrate that significant difference on personal characteristics between blood-types by using the database on recent huge questionnaires survey.

From the Database of Grants-in-Aid for Scientific Research
FY2011 Final Research Report: A demonstrative and critical study on pseudo-science for scientific literacy construction at teacher education course
代表者 武藤 浩二 Principal Investigator MUTO, Cosy (National Nagasaki Univ.)
研究分担者 長島 雅裕 Co-Investigator MASAHIRO, Nagashima (National Nagasaki Univ.)

Now, the statistical debate was already over!


3. 研究の方法
(2) JNNデータバンクの年度ごとデータ及び学生を対象に取得したアンケート調査結果を解析し、先行研究と比較することで、血液型性格判断について「予言の自己成就」現象が起きているかを調べる。

3. Method of the study
(2) To analyze data and questionnaire findings which were acquired from students together with year-serial data of the JNN data bank and check whether "self-fulfilling prophecy" exists about blood-type character judgment by comparing them with the precedent [Mr. Sakamoto's] studies.

4. 研究成果
(2) 山崎・坂元(1991)の方法に基づき、「A-B」得点を構成し、

4. Results of research
(2) Based on the method of Yamasaki, Sakamoto (1991), we constituted "A-B" score and picked up all the available data up to now (questionnaire data which includes all necessary items for both character and blood-type items to constitute A-B score) and checked how A-B scores changed according to each blood types.
As a result, after the 90s, the result of Yamasaki, Sakamoto performed fixation (difference due to blood types was stabilized) and variances became smaller after the 2000s, and it was shown that difference due to blood types was definitely statistically significant.  Although the difference was significant, the size of the difference was extremely small, and it was also shown that blood types it is not "usable" in everyday life.

(October 11, 2015)

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Last update: October 11,2015. (Minor corrections on August 12, 2017)