Ms. Watanabe


28.gif (298 バイト)Ms. Watanabe's Paper

Ms. Yoriko Watanabe's paper is very epoch-making.  In short, knowledge of blood type and personality ("bloodtype stereotypes") doesn't influence his/her answers of personality questionnaire.  So, the difference is "real" not "blood type stereotypes".

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.

This study investigates the roles that two types of information-prototype and exemplar-play in the formation of "blood type stereotypes." The result of a questionnaire study (with 112 college students) confirmed hypotheses concerning the role played by these two types of information. A substantial discrepancy was found between the subjects' beliefs about the blood type-relevant personality traits and the commonly and publicly assumed blood type traits. There also found a substantial variation in subjects' beliefs in this respect. It was found that the exemplar information played an important role, at least among some respondents, in the formation of the "blood type stereotype," such that subjects generalized their personality traits as the traits typical to people with the blood type of their own.  The other respondents, on the other hand, seemed to have formed the "blood type stereotype" by adopting the prototypical personality traits commonly believed to characterize people of their blood type.

12.gif (321 バイト)Technical Terms -- Stereotypes, Prototype and Exemplar

12.gif (321 バイト)Three Hypotheses

12.gif (321 バイト)Results

Hypothesis 1:

Correct answer rates depend on subjects' own blood types.
Famous traits showed high correct answer rates ("prudent" for Type A, "lack of prudence" for Type B, "dual personality" for Type AB and "pleasant personality" for Type O).

Hypothesis 2:

Each individuals have only 40 percent of the beliefs in common even if ones blood type is the same.
Individual's beliefs are different from other individual's ones.

Hypothesis 3:

Subjects generalized their personality traits as the traits typical to people with the blood type of their own, whether these personality traits are commonly and publicly assumed blood type-relevant personality traits or not.

Table 1  Relation between Correct Answer Rates of Each Questions and Blood Types

Blood Type

Personality Traits

Total Correct Answer Rates
One's Own Blood Type
Type A


.569 .684 n=38

Introvert, solve problem by oneself

.402 .658 n=38


.392 .474 n=38

Considerate, careful about everything

.667 .842 n=38


.441 .605 n=38

Esteem tatemae (principle) than honne (practice)


.658 n=38

Emotional and sensitive


.368 n=38


Type B

Shaken easily

.206 .440 n=25

Warm hearted

.226 .360 n=25

Have many friends, frank and sociable

.294 .400 n=25

Less influenced by the surroundings with my pace style

.402 .640 n=25
Optimistic .363 .520 n=25

Lack of prudence


.720 n=25

Active and curious


.400 n=25


Type AB Avoid close human relations .412 .333 n=12
Prudent and kind .186 .333 n=12
Fairy-tale like .157 .333 n=12
Rational thinking .245 .583 n=12
Cool and dry .510 .750 n=12
Capricious .108 .250 n=12
Moody and sometimes seem to be dual personality .608 .667 n=12


Type O Pleasant personality .549 .593 n=27
Positive and a person of action .294 .333 n=27
Demonstrate maximum courage and willpower for purpose .226 .259 n=27
Strong-willed .196 .185 n=27
Straight expression and desire .157 .185 n=27

Individualistic and sometimes self-centered

.098 .074 n=27


.284 .259 n=27



Table 2   Classification by Commonly-held Views and One's Own Judgement

Classification by One's Own Judgement

 One's Ownd

The Other

Classification by
Commonly-held Views

One's Own



The Other




12.gif (321 バイト)Another Results

Recently, I found hidden data from this paper!   Please look at carefully numbers in red.

Difference between subjects that have exact knowledge and without it

Type of subjects

Percentages of
correct answers
Correlation coefficients of
exact knowledge
and subjects' knowledge
Conviction rate
of ones' knowledge
Subjects with exact knowledge

>=.75 (n=38)

.82 .90 (SD=.96)

>=.72 (n=46)

.73 1.05 (SD=.93)
Subjects without exact knowledge

< .75 (n=56)

-.06 1.32 (SD=.91)

< .72 (n=48)

-.10 1.34 (SD=.94)

< .65 (n=35)

-.25 1.48 (SD=.84)

Subjects that have exact knowledge of blood types and personality, the exact knowledge and their knowledge are agreeing for the most part (in blue). Therefore, there is strong positive correlation between them. Conversely, subjects without exact knowledge, must have "nonexistent knowledge" or "opposite knowledge". If there is the relation between blood types and personality, there would be negative correlations between "opposite knowledge" and exact one (in red).  Namely,   it seems that there is some (small) relation between blood types and personality. But, it is not possible conclusion, just being suggesting possibility persistently, because there are not significant differences statistically. Furthermore:

These results turn over "common sense" of blood type and personality.  The more the knowledge of blood types and personality, the more "prejudice" and "harassment" is fake. Namely, people of negative feelings about blood types who intend to decrease "harassment", will get an entirely reverse effect, contrary to their original intention.  Is it a sarcastic conclusion?

(February 16, 1999)

12.gif (321 バイト)Surprising Results

I noticed incidentally there might be great differences between blood types.  So, I decided to recalculate and the results are....

Results by recalculation (Excerpts from Table 1: Relation between Correct Answer Rates of Each Questions and Blood Types)


Personality Traits

One's Own Blood Type
One's Own Blood Type χ2 p
Type A

Introvert, solve problem by oneself

.250 .658 16.50 p<0.001

Considerate, careful about everything

.563 .842 8.39 p<0.005


.344 .605 6.61 p<0.05

Esteem tatemae (principle) than honne (practice)


.658 5.31 p<0.05
Type B

Shaken easily

.130 .440 11.10 p<0.001

Warm hearted

.182 .360 3.43 p<0.10

Less influenced by the surroundings with my pace style

.325 .640 7.81 p<0.01
Optimistic .312 .520 3.54 p<0.10

Lack of prudence


.720 8.27 p<0.005
Type AB
Fairy-tale like .133 .333 3.20 p<0.10
Rational thinking .200 .583 8.41 p<0.005
Cool and dry .478 .750 3.14 p<0.10
Capricious .089 .250 2.85 p<0.10
Type O (Not Siginficant)
 p < 0.05 in red

It is natural, because these personality traits are referred to Mr. Nomi's (and other researchers) books, not pulled out from psychological tests!  Wonderful differences appear without psychological personality tests.

(March 18, 2007)

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Last update: March 18, 2007. (Minor corrections on August 12, 2017)