blood type personality theory

According to popular belief, people with type A blood are friendly and kind but also obsessive and anxious, people with type B are spontaneous and creative but can be selfish, and people with type O are confident but stubborn and aggressive. In a logical extension of this system, those with type AB are a mix of stereotypical A and B traits, while also being seen as mysterious or aloof due to their relatively low population in Japan. The minority types B and AB are more likely to be negatively stereotyped than A or O.

File:Blood type-based fortunes (2454824128).jpg

The idea that personality traits were inherited through the blood dates as far back as Aristotle.{{cite journal |author=Jon Geir Høyersten |title=From Homer to Pinel: The concept of personality from antiquity until 1800 AD |journal=Nordic Journal of Psychiatry |volume=51 |issue=5 |year=1997 |pages=385–394 |doi=10.3109/08039489709090734}}, cited in {{Cite journal|last1=Rogers|first1=Mary|last2=Glendon|first2=A. Ian|year=2002|title=Blood Type and Personality|url=https://www.researchgate.net/publication/29457792|journal=Personality and Individual Differences|volume=34|issue=7|pages=1099–1112|via=Elsevier|doi=10.1016/s0191-8869(02)00101-0}} Hippocrates also sought to link personality biologically, linking traits with the four bodily humors – sanguine, phlegmatic, choleric, and melancholic.

In 1926, Hayashi Hirano and Tomita Yajima published the article "Blood Type Biological Related" in the Army Medical Journal.

In 1927, Takeji Furukawa, a professor at Tokyo Women's Teacher's School, published his paper "The Study of Temperament Through Blood Type" in the scholarly journal Psychological Research. The idea quickly took off with the Japanese public despite Furukawa's lack of credentials, and the militarist government of the time commissioned a study aimed at breeding ideal soldiers. The study used ten to twenty people for the investigation, thereby failing to meet the statistical requirements for generalizing the results to the wider population.{{citation needed|date=August 2014}}

On the other hand, in 1934, Fisher announced the chi-squared test, which is very popular at present, for the first time. Several scholars said that they found statistically significant differences in analyzing Japanese work conducted at that time.e.g. Masao Omura (Nihon University) in "血液型と性格 Blood Type and Personality", Terumitsu Maekawa (Asia University) in "血液型人間学 Blood Type Humanics" and so on.

In another study, Furukawa compared the distribution of blood types among two ethnic groups: the Formosans in Taiwan and the Ainu of Hokkaidō. His motivation for the study appears to have come from a political incident: After the Japanese occupation of Taiwan following Japan's invasion of China in 1895, the inhabitants tenaciously resisted their occupiers. Insurgencies in 1930 and 1931 resulted in the deaths of hundreds of Japanese settlers.

The purpose of Furukawa's studies was to "penetrate the essence of the racial traits of the Taiwanese, who recently revolted and behaved so cruelly." Based on a finding that 41.2% of Taiwanese samples had type O blood, Furukawa assumed that the Taiwanese rebelliousness was genetic. His reasoning was supported by the fact that among the Ainu, whose temperament was characterized as submissive, only 23.8% is type O. In conclusion, Furukawa suggested that the Japanese should increase intermarriage with the Taiwanese to reduce the number of Taiwanese with type O blood.{{cite book | title = Criminals and their Scientists: The History of Criminology in International Perspective (Publications of the German Historical Institute) | first = Peter (Ed.) | last = Becker | publisher = Cambridge University Press | isbn = 978-0-521-81012-8 | year = 2006 |author2=Yoji Nakatani | chapter = The Birth of Criminology in Modern Japan | page = 294}}

{{Main|Masahiko Nomi}}

Interest in the theory was revived in the 1970s with a book by Masahiko Nomi, a journalist with no medical background (he graduated from the engineering department of the University of Tokyo). Few Japanese psychologists criticized him at that time,Toshinori Shirasa & Takuji Iguchi (1993), 血液型性格研究入門 血液型と性格は関係ないと言えるのか An introduction to Blood Type Personality Research – Can we say there is no relationship with blood type and personality?, pp. 209–212, 242–243. Virtually no papers nor books about blood type and personality was published from the Japanese psychological community before Masahiko Nomi's death in 1981. so he continued to demonstrate statistically significant data in various fields and published several books with these results.Masahiko Nomi analyzed various data by using statistical methods and found meaningful traits; the following are some of his works.

• Blood Type Affinity Study 5/1974 – 20,000 samples analyzed in total
• Blood Type Sports Study 10/1976 – 1,000 track-and-field athletes analyzed
• Blood Type Essence 6/1977 – listed over 1,000 people (politicians, CEOs, artists, etc.)
• Blood Type Politics Study 6/1978 – 2,000 politicians analyzed (all representatives of the national Diet, all governors, and all mayors) Later after his death in 1981, Masahiko Nomi's work was said to be largely uncontrolled and anecdotal, and the methodology of his conclusions was unclear.{{cite book | title = The Eat Right for Your Type: Complete Blood Type Encyclopedia | first = Peter J. | last = D'Adamo | publisher = Riverhead Trade | isbn = 978-1-57322-920-3 | year = 2002 | page = [https://archive.org/details/isbn_9781573229203/page/28 28] | url-access = registration | url = https://archive.org/details/isbn_9781573229203 }} Because of this, he was heavily criticized by the Japanese psychological community, although his books remain popular. His son, Toshitaka Nomi, continued to promote the theory with a series of books and by running the Institute of Blood Type Humanics.{{cite web | last = Evans | first = Ruth | title = Japan and blood types: Does it determine personality? | url = https://www.bbc.co.uk/news/magazine-20170787 | work = BBC News | date = 4 November 2012 | access-date = 5 November 2012 }} He later established the [http://www.human-abo.org/ Human Science ABO Center] for further research and publication in 2004.

{{More medical citations needed|section|date=March 2023}}

Kengo Nawata, a social psychologist, studied blood type correlations in a survey of 68 personality traits given to over 10,000 people from Japan and the US. His statistical analysis found that less than 0.3% of the total variance in personality was explained by blood type.

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. These results indicated that Japanese blood-typical stereotypes influenced their self-reported personalities{{snd}}like a self-fulfilling prophecy.

Cosy Muto and Masahiro Nagashima et al. (Nagasaki University) conducted a supplementary survey of Yamazaki and Sakamoto in 2011. They demonstrated that significant and the same difference in personalities between blood-types by using the same database as Samamoto and Yamazaki used. In the 1990s, the difference due to blood types was stabilized and variances became smaller. Then in the 2000s, the difference was statistically significant, too. However, the effect magnitude was extremely small, despite 'significance' in the statistical sense.

Another Japanese social psychologist, Shigeyuki Yamaoka (Shotoku University), announced results of his questionnaires, which were conducted in 1999 (1,300 subjects)Shigeyuki Yamaoka (1999), 血液型ステレオタイプが生み出す血液型差別の研究 A Study on Blood Harassment Caused by Blood-typical Stereotypes, Paper presented at the 40th annual convention of the Japanese society of social psychology. Tokyo. For further information of this paper, confer to Shigeyuki Yamaoka (2001), ダメな大人にならないための心理学 A Psychology Book for not to Become a Useless Adult, pp. 35–73 {{ISBN|4-89242-665-2}} and 2006 (1,362 subjects),Shigeyuki Yamaoka (2006), [https://web.archive.org/web/20210224180156/http://www.wdc-jp.biz/cgi-bin/jssp/wbpnew/master/download.php?submission_id=2006-E-0375&type=1 血液型性格項目の自己認知に及ぼすTV番組視聴の影響 Influence of Watching TV programs to One's Self-recognition of the Blood-type personality Items] Paper presented at the 47th annual convention of the Japanese society of social psychology. Tokyo. In both cases, the subjects were university students, and only subjects with enough knowledge of and belief in the "blood-type diagnosis" showed meaningful differences. He concluded that these differences must be the influence of mass media, especially TV programs. Yamaoka later examined 6,660 samples from 1999 through 2009 in total and found the same result.Shigeyuki Yamaoka (2009), [http://ci.nii.ac.jp/els/110007674296.pdf?id=ART0009487281&type=pdf&lang=jp&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1444739076&cp= 血液型性格判断の差別性と虚妄性(自主企画(2)) Segregation and falsehood of blood-type personality analysis]{{Dead link|date=June 2019 |bot=InternetArchiveBot |fix-attempted=yes }}, self planning session (2) at the 18th annual convention of the Japanese society of personality psychology.

On the other hand, some{{Who|date=May 2024}} believe that the statistically meaningful differences according to the blood types are not explained only by beliefs, nor that they are a self-fulfilling prophecy. In Japan, the penetration rate{{Definition needed|date=May 2024}} of blood-typical personality traits was investigated. Yoriko Watanabe, a psychologist at Hokkaido University, chose "well-known" traits and found most traits were known to no more than half of Japanese people (subjects were university students).Watanabe, Y. (1994). [http://ci.nii.ac.jp/naid/110002785240 血液型ステレオタイプ形成におけるプロトタイプとイグゼンブラの役割 The roles of prototype and exemplar in the formation of the "blood type stereotype"] {{Webarchive|url=https://web.archive.org/web/20140819083944/http://ci.nii.ac.jp/naid/110002785240 |date=2014-08-19 }}. Japanese Journal of Social Psychology, 10–2, 77–86. She extracted 7 traits for each of 4 blood types which were common to three or more "blood type diagnosis" books. 20 items of all 28 showed less than 50% penetration (the average was 46.1%). A Japanese writer, Masayuki Kanazawa, analyzed these blood-typical traits in combination with data from Yamaoka (1999) that used the same items from Watanabe's penetration survey. If blood-typical differences are caused by penetration (or their self-recognition), the rate of differences of a trait is proportional to the rate of its penetration.{{Clarify|date=May 2024}} However, Kanazawa was not able to discover any association with blood-type differences and penetration rates.Masayuki Kanazawa (2014), 統計でわかる血液型人間学入門 An Introduction to Blood Type Humanics - Understanding by Statistics, Gentosha Runaissance {{ISBN|978-4-7790-1109-2}} pp. 16–36 This result raises doubt{{Among whom?|date=May 2024}} about the role of beliefs and self-fulfilling prophecy.{{scientific citation needed|date=May 2024}}

Most reports that demonstrated statistical correlation attribute differences to a self-fulfilling prophecy. However, no study directly proved the existence of "self-fulfillment". Therefore, the opinions of researchers are varied at present{{Citation needed|date=May 2024|reason=We cannot just say this, firstly because it does not seem to be the case, and secondly because original research is not allowed on Wikipedia. If the opinions of researchers on this issue are best summed up overall as "varied at present" due to the absence of direct proof of self-fulling prophecy, a secondary source that makes this assessment must be cited.}}:

1. Whether there is a statistical correlation or not;
2. Whether any statistical correlations are superficial, being caused by subjects' self-fulfilling prophecy, or if they are truly caused by the blood type.

In a 2021 Japanese study, ANOVA results of a 6,000-population large-scale survey showed that respondents displayed the personality traits corresponding to their own blood type more strongly than respondents who had different blood types did. This finding was consistent across all traits, and all differences were statistically significant. The same differences in scores were found in the groups who reported no blood type personality knowledge, although the values were smaller.Kanazawa, M. (2021). [http://article.sapub.org/10.5923.j.ajis.20211101.01.html A Pilot Study Using AI for Psychology: ABO Blood Type and Personality Traits] {{Webarchive|url=https://web.archive.org/web/20210407195809/http://article.sapub.org/10.5923.j.ajis.20211101.01.html |date=2021-04-07 }}. American Journal of Intelligent Systems, 11(1), 7–12.

The five-factor model tests were carried out in several countries, including Japan, Korea, and Taiwan, after the year 2000. These tests were intended to digitize self-ratings of the "big five" personality traits. It was expected that differences in self-reported personalities (a self-fulfilling prophecy) would be detected from the subject who believed in blood-typical stereotypes. As a result, researchers found no meaningful statistical difference.So Hyun Cho, Eun Kook M. Suh, Yoen Jung Ro (2005), [http://kiss.kstudy.com/journal/thesis_name.asp?tname=kiss2002&key=2498184 Beliefs about Blood Types and Traits and Their Reflections in Self-reported Personality] {{Webarchive|url=https://web.archive.org/web/20160303205114/http://kiss.kstudy.com/journal/thesis_name.asp?tname=kiss2002&key=2498184 |date=2016-03-03 }}, Korean Journal of Social and Personality Psychology, 19(4), 37–47.Yoshio Kubo, Yukiko Miyake (2011), [http://ci.nii.ac.jp/naid/110008427667 血液型と性格の関連についての調査的研究 Correlation between blood types and personalities] {{Webarchive|url=https://web.archive.org/web/20140819084710/http://ci.nii.ac.jp/naid/110008427667 |date=2014-08-19 }} Bulletin of Kibi International University (Department of Social Welfare), 21, 93–100.

So Ho Cho, a Korean psychologist (Yonsei University), and the others carried out a questionnaire about blood-typical items to subjects and discovered statistical differences as expected. However, the difference was not found when the five-factor model for big five personality traits was administered to the same subjects. Another Korean researcher Sohn (Yonsei University) re-analyzed Cho's data.Sung Il Ryu, Young Woo Sohn (2007), [https://www.kci.go.kr/kciportal/landing/article.kci?arti_id=ART001077625 A Review of Sociocultural, Behavioral, Biochemical Analyses on ABO Blood-Groups Typology] {{Webarchive|url=https://web.archive.org/web/20220227144358/https://www.kci.go.kr/kciportal/landing/article.kci?arti_id=ART001077625 |date=2022-02-27 }}, The Korean Journal of Social and Personality Psychology He found that several independent items of the big five personality test detected differences according to each blood-typical stereotype. However, these differences became extinct in the process of plural items being gathered to five factors (big five). If these results are correct, the five-factor model test cannot detect differences between the blood types – if such a causal link did indeed exist.Masayuki Kanazawa (2018), Blood Type and Personality 3.0 – Reality Proved by 300,000 People and AI, CreateSpace {{ISBN|978-1-9866-2381-0}} pp. 119–122. This book analyzed 14 reports of the "Big Five" test and obtained no consistent result.

In 2014, a Korean matchmaking company 듀오 Duo conducted a research survey examined 3,000 couples and found that blood type had no significant impact on the possibility of a couple getting married.{{cite web|url= https://hyphe-nated.com/odd-questions-and-compliments-from-koreans-whats-your-blood-type-what-a-small-face-head-you-got-i-envy-you-why-do-koreans-ask-if-you-ate-what-happens-when-you-eat-alone//|archive-url= https://web.archive.org/web/20210911003415/https://hyphe-nated.com/odd-questions-and-compliments-from-koreans-whats-your-blood-type-what-a-small-face-head-you-got-i-envy-you-why-do-koreans-ask-if-you-ate-what-happens-when-you-eat-alone/|url-status= usurped|archive-date= September 11, 2021|title= What's your blood type? What a small face! Odd Korean questions & compliments|publisher= Hyphe-Nated| access-date= 11 September 2021}}

In 2017, a meta-analysis of studies, using the Big Five personality test, involving 260,861 subjects found that six genes affected human personality.{{cite journal | doi=10.1038/ng.3736 | volume=49 | title=Genome-wide analyses for personality traits identify six genomic loci and show correlations with psychiatric disorders | year=2017 | journal=Nature Genetics | last1 = Lo | first1 = Min-Tzu | last2 = Hinds | first2 = David | last3 = Tung | first3 = Joyce | issue=1 | pages=152–156 | pmid=27918536 | pmc=5278898 }} However, the coefficient of determination was as low as 0.04%. This is usually considered to be an error.

In order to avoid the influence of "contamination by knowledge", a Japanese psychologist group published a series of studies, but no significant differences were found except for Japanese prime ministers.{{cite journal |author=Ohmura, M. |author2=Ukiya, S. |author3=Fujita, S. |date=2013 |title=Is the "Blood Type Personality Theory" Reliable? (Part 30) I – Do Members of the House of Representatives Show Blood Type Characteristics? |journal=Proceedings of the Annual Meeting of the Japan Association of Applied Psychology |volume=80 |page=61 }}{{cite journal |author=Ukiya, S. |author2=Ohmura, M. |author3=Fujita, S. |date=2013 |title=Is the "Blood Type Personality Theory" Reliable? (Part 30) II – Blood type distribution of Japanese and Korean celebrities |journal=Proceedings of the Annual Meeting of the Japan Association of Applied Psychology |volume=80 |page=62 }}{{cite journal |author=Fujita, S. |author2=Ohmura, M. |author3=Ukiya, S. |date=2013 |title=Is the "Blood Type Personality Theory" Reliable? (Part 30) III – Can we see blood type traits in athletes? |journal=Proceedings of the Annual Meeting of the Japan Association of Applied Psychology |volume=80 |page=63 }}{{cite journal |author=Ukiya, S. |author2=Ohmura, M. |author3=Fujita, S. |date=2014 |title=Is the "Blood Type Personality Theory" Reliable? (Part 31) – Blood types of Japanese sumo wrestlers |journal=Proceedings of the Annual Meeting of the Japan Association of Applied Psychology |volume=81 |page=53 }} Later, it was reported that significant differences were found not only for prime ministers, but also for foreign ministers, education ministers, professional baseball hitters, and soccer players in Japan.{{cite journal |author=Masayuki Kanazawa |date=2021 |title=Linkage between ABO Blood Type and Occupation: Evidence from Japanese Politicians and Athletes |journal=International Journal of Social Science Studies |volume=9 |issue=5 |pages=104–111 |doi=10.11114/ijsss.v9i5.5282 |doi-access=free }}

Kim and Yi (Seoul University of Venture & Information) measured the brain waves of 4,636 adults. They reported that type O people were most stress-resistant.Choong-Shik Kim, Seon-Gyu Yi (2011), [http://kiss.kstudy.com/journal/thesis_name.asp?tname=kisskw&key=50117192 A Study on the effects of one's blood type on emotional character and antistress of adults] {{Webarchive|url=https://web.archive.org/web/20160303222642/http://kiss.kstudy.com/journal/thesis_name.asp?tname=kisskw&key=50117192 |date=2016-03-03 }}, Journal of the Korea Academia-Industrial cooperation Society, 12(6), 2554–2560. According to this article "meaningful difference had been revealed between the blood type and stress resistancy; type O rated higher scores in awareness and stress resistancy then other types. ..."

In Japan, blood types are often used in women's magazines to determine relationship compatibility with potential or current partners. Blood type horoscopes are featured in morning television shows and daily newspapers. The blood types of celebrities are often listed in their infoboxes on Japanese Wikipedia.{{cite web|url=http://www.mentalfloss.com/blogs/archives/99865|title=Type Cast: The Japanese Fascination with Blood Types|date=13 September 2011 |access-date=21 July 2012|archive-url=https://web.archive.org/web/20120619031050/http://www.mentalfloss.com/blogs/archives/99865|archive-date=2012-06-19}} The four books of a series that describe people's character by blood type each ranked third, fourth, fifth, and ninth on a list of best-selling books in Japan in 2008.[http://www.japantimes.co.jp/news/2008/12/31/news/blood-types-do-they-shape-a-personality-or-mere-stereotypes/ Blood Types – Do They Shape a Personality or Mere Stereotypes] {{Webarchive|url=https://web.archive.org/web/20151117021943/http://www.japantimes.co.jp/news/2008/12/31/news/blood-types-do-they-shape-a-personality-or-mere-stereotypes/ |date=2015-11-17 }}, Natsuko Fukue, The Japan Times, December 31, 2008

One survey showed that at least two-thirds of respondents from Chinese-speaking East Asian countries and regions believe in an association between blood types and personality.{{Cite web |title=(PDF) Blood type and the five factors of personality in Asia |url=https://dokumen.tips/documents/blood-type-and-the-five-factors-of-personality-in-asia.html |access-date=2023-10-11 |website=dokumen.tips |language=en}}

In a Japanese survey, more than half of Japanese respondents stated they were fond of talking about personalities based on blood types.Reiko Yamashita (2008), [http://db1.wdc-jp.com/cgi-bin/jssp/wbpnew/master/detail00.php?submission_id=2008-E-0208 血液型性格判断はなぜすたれないのか why doesn't blood type in Japanense culture detariorate?] {{webarchive |url=https://web.archive.org/web/20140826120840/http://db1.wdc-jp.com/cgi-bin/jssp/wbpnew/master/detail00.php?submission_id=2008-E-0208 |date=August 26, 2014 }}, Paper presented at the 48th annual convention of the Japanese society of social psychology. The research also stated that people in Japan like blood-typical personality diagnoses, believe there is a relationship between blood type and personality, and feel its traits apply to themselves to a certain degree. Two other surveys showed similar results.The following are results of two Japanese surveys:

• Yahoo! Research (December 25, 2008)『「血液型本」に関する調査』 A survey about "blood type books" – "My personality is appropriately expressed so that sympathized, convinced" (66%), "Can grasp my personality objectively with new discovery" (59%), "One of the means and the methods to express my personality" (50%), "Useful in acquaintances" (48%) and "Useful in love-affiliated things" (47%).
• Yumiko Kamise, Yutaka Matsui (1996), 血液型ステレオタイプ変容の形 —ステレオタイプ変容モデルの検証— Changing processes of stereotype on blood-groups, Japanese Journal of Social Psychology, 11–13, 170–179. – "blood-typical personality diagnosis is a fun" (83.6%), "I like blood-typical personality diagnosis" (61.5%).

Although there is no proven correlation between blood type and personality, many matchmaking services use it. In this way, it is similar to the use of astrological signs, which are also popular in Japan. Asking one's blood type is common in Japan, and people are often surprised when a non-Japanese person does not know their blood type.[https://web.archive.org/web/20110605133206/http://www.japantoday.com/category/lifestyle/view/in-japan-you-are-what-your-blood-type-is In Japan, you are what your blood type is], Japan Today

It is common among anime and manga authors to mention their characters' blood types and to give their characters blood types to match their personalities.{{cite book|last=Brenner|first=Robin E.|title=Understanding manga and anime|url=https://books.google.com/books?id=uY8700WJy_gC&pg=PA41|year=2007|publisher=Libraries Unlimited|isbn=978-1-59158-332-5|page=41}} Some video game characters also have known blood types. Some video game series also have blood type as a customisable option in their creation modes.

The Reconstruction Minister Ryu Matsumoto had to resign after abrasive comments towards the governors of Iwate and Miyagi.{{cite news|last=Fukue |first=Natsuko |url=http://search.japantimes.co.jp/cgi-bin/nn20110705a2.html |title=Matsumoto rips Tohoku governors |publisher=The Japan Times |date=2011-07-05 |access-date=2014-04-12}} Afterwards, he partially blamed his behavior on his blood type, saying "My blood is type B, which means I can be irritable and impetuous, and my intentions don't always come across."{{cite news | url=https://www.reuters.com/article/us-politics-blood-idUSTRE7653PC20110706 | work=Reuters | first=Elaine | last=Lies | title=Blame it on my blood, disgraced Japan politician says | date=2011-07-06 | access-date=2017-06-30 | archive-date=2015-09-24 | archive-url=https://web.archive.org/web/20150924154038/http://www.reuters.com/article/2011/07/06/us-politics-blood-idUSTRE7653PC20110706 | url-status=live }}

Blood types are important in South Korea as well. The Korean webcomic A Simple Thinking About Blood Type depicts stereotypes of each blood type and has been adapted as a short anime series in Japan as Ketsuekigata-kun! in 2013 and 2015.

Blood type harassment, called {{Transliteration|ja|bura-hara}} (wasei-eigo: a portmanteau of blood and harassment), has been blamed for bullying of children in playgrounds, loss of job opportunities, and the end of relationships.{{cite news|url=https://www.theguardian.com/world/2008/dec/04/japan-world-news|title=Typecast – Japan's obsession with blood groups|last=McCurry|first=Justin|date=4 December 2008|newspaper=The Guardian|access-date=14 December 2012}}

Discrimination based on blood type has been reported in Japan and Korea. Examples include questions about blood types during job interviews despite government warnings against this, children being split up at school according to their blood type, a national softball team customizing training to fit each player's blood type, and companies giving work assignments according to employees' blood type.{{cite news|url=http://www.huffingtonpost.com/2009/02/01/in-japan-your-blood-type-_n_162917.html|title=In Japan, Your Blood Type Says It All|last=Yamaguchi|first=Mari|date=2009-02-01|publisher=Huffington Post|access-date=2014-04-12}}

However, these examples are contested and deemed. Two counter-arguments are usually cited. Firstly, there have been no trials related to blood-type discrimination thus far. Secondly, most Japanese people do not think blood types determine their personalities, but rather affect them to some degree.

• Barnum effect
• Blood type diet
• Astrological signs—a similar framework popular in Western culture, using the positions of stars on a person's birthday to predict their personality.

{{Reflist}}

• Constantine, Peter. What's Your Type?: How Blood Types Are the Keys to Unlocking Your Personality. 1997. Plume, {{ISBN|0-452-27802-3}}.
• {{cite journal | last1 = Jun Kim | first1 = Beom |display-authors=et al | year = 2007 | title = Blood-type Distribution | journal = Physica A | volume = 373 | issue = 1| pages = 533–540 | doi=10.1016/j.physa.2006.05.027| bibcode = 2007PhyA..373..533K }}
• {{cite journal | last1 = Miller | first1 = Laura | year = 1977 | title = People Types: Personality Classification in Japanese Women's Magazines | journal = The Journal of Popular Culture | volume = 11 | issue = 2| pages = 436–452 }}
• {{cite journal | last1 = Nawata | first1 = Kengo | year = 2014 | title = No relationship between blood type and personality: Evidence from large-scale surveys in Japan and the US | url = https://www.jstage.jst.go.jp/article/jjpsy/85/2/85_85.13016/_pdf | journal = The Japanese Journal of Psychology | volume = 85 | issue = 2| pages = 148–156 | doi=10.4992/jjpsy.85.13016| pmid = 25016835 | doi-access = free }}
• Nomi, Toshitaka, and Alexander Besher, You Are Your Blood Type: The Biochemical Key to Unlocking the Secrets of Your Personality. New York: Pocket Books, 1988. {{ISBN|0-671-63342-2}}.
• {{cite journal | last1 = Sakamoto | first1 = A. | last2 = Yamazaki | first2 = K. | year = 2004 | title = Blood-typical personality stereotypes and self-fulfilling prophecy: A natural experiment with time-series data of 1978–1988 | url = http://www.hss.ocha.ac.jp/psych/socpsy/sakamoto/media/2003-2004/blood%20typical.pdf | journal = Progress in Asian Social Psychology | volume = 4 | pages = 239–262 | access-date = 2014-08-12 | archive-url = https://web.archive.org/web/20160122125350/http://www.hss.ocha.ac.jp/psych/socpsy/sakamoto/media/2003-2004/blood%20typical.pdf | archive-date = 2016-01-22 }}

• [https://web.archive.org/web/20110106040507/http://cat.inist.fr/?aModele=afficheN&cpsidt=16459254 Blood type and the five factors of personality in Asia]
• [https://www.japanvisitor.com/japanese-culture/culture-blood-types Japanese Blood Types]
• [http://www.human-abo.org/ Human Science ABO Center]
• [http://www.dadamo.com/ Website of Peter J. D'Adamo]

{{DEFAULTSORT:Blood Types In Japanese Culture}}

Personality theory

Blood types

Category:Personality typologies

Category:Pseudoscience