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Testing the Barnum Effect in
Personality Assessment
By:
Rodrigo V. Lopiga
Polytechnic University of the Philippines
February, 2017
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Testing the Barnum Effect in Personality Assessment
Abstract
The purpose of this study is to review past studies and conduct similar experiment on Barnum
Effect to forty (40) Generation Z students and to compare if there is a significant difference
between males and females. The Barnum effect has been implicated in personal validation,
this causes us to see connections where there is no reliability of interpretations given and we
believe them to be true. This study attempts test the Barnum Effect in personality assessment.
The researchers found out that Barnum effect is present and that there was no significant
difference between male and female participants. Overall, the level of accuracy of the
interpretation was perceived as highly accurate because it provides general interpretation of
one’s traits. The Barnum Principle in Psychological testing and assessment may affect the
misinterpretation of test results in the assessment of personality.
Keywords: Barnum, Barnum effect, Personality Assessment, Psychological Testing,
Psychological Assessment.
Introduction
Barnum Effect, also called Forer Effect, in psychology, the phenomenon that occurs
when individuals believe that personality descriptions apply specifically to them (more so
than to other people), despite the fact that the description is actually filled with information
that applies to everyone. The effect means that people are gullible because they think the
information is about them only when in fact the information is generic. The Barnum Effect
came from the phrase often attributed (perhaps falsely) to showman P. T. Barnum that a
“sucker” is born every minute. Psychics, horoscopes, magicians, palm readers, and crystal
ball gazers make use of the Barnum Effect when they convince people that their description
of them is highly special and unique and could never apply to anyone else.
According to K. D. Vohs (2016), the Barnum Effect has been studied or used
in psychology in two ways. One way has been to create feedback for participants in
psychological experiments, who read it and believe it was created personally for them. When
participants complete an intelligence or personality scale, sometimes the experimenter scores
it and gives the participant his or her real score. Other times, however, the experimenter gives
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participants false and generic feedback to create a false sense (e.g., to give the impression
they are an exceptionally good person). The reason that the feedback “works” and is seen as a
unique descriptor of an individual person is because the information is, in fact, generic and
could apply to anyone. The Barnum Effect works best for statements that are positive. People
are much less likely to believe that a statement applies to them when it is a negative
statement, such as “I often think of hurting people who do things I don’t like.” Thus, Barnum
Effect reports primarily contain statements with mostly positive items.
The researcher, noticed that numerous of recent article have a reference from a review
of Barnum Effect in Personality Assessment made in 1985 by D. H. Dickson and I. W. Kelly,
thus the researcher studied and cited some information from it. This review had mentioned
the history and factors that affected the earlier studies of this phenomenon. They described
the Barnum profiles consists of a variety of statements: "Vague, e.g., 'you enjoy a certain
amount of change and variety in life'; Double-headed, e.g., 'you are generally cheerful and
optimistic but get depressed at times'; Modal characteristics of the subject's group, e.g., 'you
find that study is not always easy'; favorable, e.g., 'you are forceful and well-liked by others'"
What is of interest to the psychologist is that when Barnum profiles are perceived as
accurate, subjects increase their faith in the validity of the assessment device. Furthermore,
clinicians may be reinforced by clients' praise for producing vague and general interpretations
and reinforced even more for these than for more accurate and specific statements. Hence, the
importance of the phenomenon lies in that the extent that genuine (or bogus) profiles
incorporate Barnum statements, they will be perceived as accurate, giving an illusion of
validity.
The beginning of the study of this phenomenon, said by Dickson and Kelly, was
Forer's Research. Forer (1949) initiated empirical research targeted at discovering the extent
to which individuals accept general personality descriptions as true of themselves. Forer
administered the Diagnostic Interest Blank to 39 students in his introductory psychology
class. One week later he gave each subject an identical personality description consisting of
vague, ambiguous, and general statements, which came largely from a newsstand astrology
book. Students were asked to rate the accuracy of their profiles on a scale of 0 (poor) to 5
(perfect). The mean accuracy rating was 4.3. Nobody rated them less than 2, and only 5
subjects rated them less than 4.
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In general, subsequent studies of the Barnum effect have expanded upon Forer's ideas
and questions and have utilized a similar methodological approach. Subjects (a) are
administered a personality test, (b) wait while the test is scored, (c) receive a personality
profile purportedly derived from the personality test they wrote, and (d) rate the personal
accuracy of the profile. In most cases the subjects receive identical personality sketches.
Dickson and Kelly's Review stated variables that affected and tested in the earlier
studies of Barnum Principle. The variables mentioned were generality of interpretation,
apparent relevance of interpretation, favorability of interpretation, and type of assessment
procedure.
Generality of interpretation - It has been repeatedly demonstrated that general personality
profiles supposedly derived from psychological assessment are judged by subjects to be
accurate descriptions of them. The bulk of researchers investigating the Barnum effect have
used a research approach similar to Forer's (1949), perhaps varying the personality inventory
from which the profile is purportedly derived, and have arrived at the same conclusion,
namely, that most subjects rate the general Barnum profile as either good or excellent
descriptions of their own personalities.
Several researchers suggest that the reason for the overwhelming acceptance is
because Barnum statements have a high base rate of occurrence in the general population,
that is, is universally valid. Others suggest that the situation is more complicated. It maybe
that different items in a Barnum profile are accepted because the wording allows the subjects
to project their own interpretations onto them. Other statements may be accepted because
they involve socially desirable characteristics and still others because the descriptions are
genuine characteristics of most people. It is important to note that a great deal of the
Barnum literature seems to assume that people do not have insight into their own
personalities and that they are therefore gullible, which leads them to accept Barnum
statements. But surely this view is incorrect. People accept many Barnum statements
because they do fit, and because they do not have anything else with which to compare them.
If the statement fits, it must necessarily be accepted. or example, although almost everyone
accepts "You have a tendency to be critical of yourself" and "At times you are extraverted,
affable, sociable, while at other times you are introverted, wary, reserved as true of
themselves (Bachrach&Pattishall, 1960), it is unlikely that most people would be as accepting
of specific non-Barnum statements such as "You have two eyes, one brown and one grey."
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People often have no trouble distinguishing between true and false feedback of 2 specific
natures when it is presented to them (Dana & Fouke, 1979).
Apparent relevance of interpretation - Snyder and Larson (1972) were the first researchers
to test the hypothesis that labeling a general personality interpretation as being specifically
"for you" can increase acceptance of that interpretation. In this study one group of subjects
was told that their personality interpretation was derived "specifically for them" and a second
group was told that their interpretation was "generally true of people." Subjects who were
told that their general personality interpretation was "for them" rated the interpretation as a
more accurate description of their own personalities than subjects who were told that the
interpretation was "for people in general."
Using a slightly different approach and measurement technique, Ziv and Nevenhaus
(1972) and Hampson (1978) tested Forer's (1949) speculation that individuals accept general
personality descriptions for themselves while failing to recognize their applicability to the
general population. The researchers used a within-subject design and asked that all subjects
rate the accuracy of "their" personality description both for themselves and for people in
general. Ziv and Nevenhaus (1972) and Hampson (1978) found that individuals rated "their"
interpretation as being more true of themselves than of people in general. These results were
aIso replicated in studies by Snyder and Shenkel (1976) and Baillargeon and Danis (1984).
The effect of relevance in these - studies was qualified by an interaction between favorability
and relevance.
In contrast to Snyder, et al. (1976), Greene (1977) stated that the "illusion of
uniqueness" cannot be measured by asking the subjects, "Is this description accurate?" rather
it must be directly measured by the question, "Does this interpretation describe you as a
unique person?" When asked these questions Greene found that subjects rated the generalized
interpretation as an accurate description of their personalities but did not rate it as a
description of their unique personality. These subjects realized that the generalized
interpretation did not accurately describe them as unique individuals and that the same
interpretation could as accurately be applied to any of their classmates. It is clear that
students can assess the accuracy and the triviality of generalized interpretations if they
are asked to do so.
Favorability of interpretation. The acceptance of Barnum profiles is affected by the
favorability of the personality sketch. Sundberg (1955) provided indirect evidence that
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subjects preferred interpretations containing favorably as opposed to unfavorably worded
statements. He based his conclusions on two judges' a post hoc evaluations that there were
five times as many favorable as unfavorable statements in the most highly accepted
interpretations and two times as many favorable statements as unfavorable statements in the
least accepted interpretations.
Weisberg (1970) and Marks and Karnmann (1980) found that the extent to which
subjects assented to the validity of both positively and negatively worded statements was
related to the over-all context of the Barnum personality profile. Both studies found that,
although favorably worded interpretations are preferred, whether the over-all feedback was
negative or positive influenced the extent to which negatively worded individual statements
were accepted.
Several reasons for the higher accuracy rating of favorable interpretations as opposed
to unfavorable ones have been proposed. Snyder and Shenkel (1976) suggested that
situational variables such as the favorability of the interpretation may exert little independent
influence upon the subjects' acceptance of general personality interpretations. Snyder and
Shenkel (1976) and Weinberger (1980) pointed out that, when the favorability of an
interpretation is changed, the base rate truthfulness is altered. Marks and Kammann (1980)
noted that students would even accept specific, inaccurate feedback as descriptive of
themselves, albeit not very highly. They concluded that whatever they said was seen as true
by the students and that the Barnum effect relies heavily on the power of suggestion.
Type of assessment procedure -The evidence regarding effects of the various assessment
devices upon subjects' acceptance of personality interpretations has been inconsistent and
subject to methodological criticism (Weinberger, 1980).
Snyder (1974) obtained statistically significant results indicating differential acceptance of
identical Barnum profiles when the type of assessment varied. He reported that subjects rated
profiles purportedly derived from projective techniques (n = 26, M = 4.54) higher than those
from an interview (n = 28, M = 4.36) or an objective personality test (n = 27, M = 4.22). A
total of 74 subjects were divided into one of three conditions: (1) a projective assessment
procedure (Rorschach) where 90% of the subjects rated the accuracy of "their" profile as
either excellent or good, (2) an interview procedure (structured questionnaire) where 80% of
the subjects rated the accuracy of "their" profile as either excellent or good, and (3) objective
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procedure (the Bernreuter) where 74% of the subjects rated the accuracy of "their" profile as
either excellent or good.
Members of the Rorschach group did, however, view "their" interpretation as greater
in depth than did the members of either the Questionnaire (Mann-Whitney U = 152, p < .05)
or the Bernreuter (U = 127.5, p < .05) groups. Snyder, Larsen, and Bloom (1976) report a
trend such that the projective technique was rated as most accurate (n = 26, M = 4.54),
followed by graphological technique (n = 64, M = 3.52) and horoscopes (n = 64, M = 3.44),
however, no statistically significant differences were found. Collins, et al. (1977) found that
acceptance racing of Barnum statements purportedly derived from a valid personality test (n
= 16, M = 4.06) did not differ significantly from those purportedly derived from a satirical
one (n = 13, M = 3.84).
On the basis of the research reviewed, one can, with some confidence, state several
propositions. (1) Subjects perceive Barnum statements to be accurate descriptions of them.
(2) One can increase acceptance of a Barnum profile by labeling the profile "for you." (3)
Subjects can distinguish between the accuracy and uniqueness of a Barnum description when
they are specifically asked to do so. It is unclear whether or not subjects do so when not
directly asked.
III. Methodology
In this experiment the researcher gathered forty (40) Generation Z students to take
satirical 35-item objective test. Participants inform that they will take a personality test. The
researchers gave instructions to participants: "The test consist of 35-items T or F Personality
Test. There are no wrong answers to the test. After taking the test, we will analyze and give
personality assessment based on the answers."After every participant took the test, we
informed themand meet in a later day. All participants get identical personality assessment
without their knowledge.
"You have a strong need for other people to like you and for them to admire
you. You have a tendency to be critical of yourself. You have a great deal of
unused energy that you have not turned to your advantage. Although you have
some personality weaknesses, you are generally able to compensate for them.
Your sexual adjustment had presented some problems for you.
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Disciplined and controlled on the outside, you tend to be worrisome and
insecure inside. At times, you have serious doubts as to whether you have
made the right decision or done the right thing. You prefer a certain amount of
change and variety and become dissatisfied when hammed in by restrictions
and limitations.
You pride yourself on being an independent thinker and do not accept other
opinions without satisfactory proof. You have found it unwise to be too frank
in revealing yourself to others. At times, you are extroverted, affable, and
sociable, whereas at other times you are introverted, wary, and reserved.
Some of your aspirations tend to be pretty unrealistic."
Lastly, researchers ask them to rate how accurate the assessment. Rate from 1 to 5; 1 for least
accurate, 2 for slightly accurate, 3 for moderately accurate, 4 for moderately accurate, and 5
for very high accuracy. Gather all the data.
Rating Description
1 Least Accurate
2 Slightly Accurate
3 Moderately Accurate
4 Highly Accurate
5 Very High Accurate
IV. Results
In this experiment participants agreed that the interpretation made was accurate though it was
a general statement applicable to all. Thus, the experiment proved that Barnum Principle is
present.
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Table 1
The mean scores of the respondents when grouped according to gender
GENDER N MEAN SD
Male 12 4.0833 1.o8362
Female 28 4.1071 .95604
The results of male and female had no significant difference. The twelve (12) male
participants had a mean average rating of accuracy of 4.0833 while the twenty-eight (28)
female participants had a mean average rating of accuracy of 4.1071.
two participants (5.0%) rated least accurate, while 0 (0.0%) participant rated slightly
accurate, 5 (12.5%) participants rated moderately accurate, 18 (45.0%) participants rated
highly accurate, and 15 (37.5%) participants rated very high accuracy.
Most of the participants rated our given satirical and general interpretation a highly accurate
rating even if the said interpretation is general and can be applicable to all.
V. Discussion
In this experiment, the researchers compared males and females on who is most likely
to affect and think that bogus and general interpretations are accurate assessment of their
personality. The researcher noticed that there was no significant difference in their mean
accuracy rating. Most of our participants accumulated 45% of the over-all sample had rated
our interpretation as highly accurate and only 5% rated less than 2. Thus, the researchers
concluded that there was no significant difference in believing whether a general Barnum
statement is accurate for them or not and they think that the interpretation was highly
accurate and fitted for them although it was a general statement that can be applicable to
everyone. General population may believe in fortune telling, astrology, palm reading, and
others although it is not scientific.
The researcher tried to replicate Forer's Research and test and found out that the
results are identical. Though the mean accuracy 4.1 is lesser than Forer's mean accuracy 4.3.
There are two (2) subjects that gave a rating of less than 2 which is lesser rating than Forer's
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Table 2
The perceived Accuracy of the personality description
ACCURACY FREQUENCY PERCENT
Least Accurate 2 5.0
Moderately Accurate 5 12.5
Highly Accurate 18 45.0
Very High Accurate 15 37.5
TOTAL 40 100.0
study that had zero (0). Seven (7) subjects rated less than 4, where Forer got five (5) which is
lesser as well.
However, the researcher accepted the variables proposed by Dickson and Kelly;
generality of interpretation, and favorability of interpretation. the given assessment had
variety of double-barreled statements; "Although you have some personality weaknesses, you
are generally able to compensate for them.", "Disciplined and controlled on the outside, you
tend to be worrisome and insecure inside.", "At times, you are extroverted, affable, and
sociable, whereas at other times you are introverted, wary, and reserved." and favorable
statements, "You have a great deal of unused energy that you have not turned to your
advantage." Although accepted, the researcher concluded that culture and year of conducted
research can affect the results drastically. At present, more people tend to become more wary
of bogus interpretations of themselves and acknowledge it. Therefore, we conclude that
although most subjects rated 4 or 5, as years passed (including age), people become more
aware of satirical descriptions of themselves.
VI. References
D. H. Dickson And I. W. Kelly, The 'Barnum Effect' In Personality Assessment: A Review Of
The Literature,1985
https://cortecs.org/wp-content/uploads/2014/12/the-barnum-effect-in-personality-assessment-
a-review-of-the-literature.pdf?fbclid=IwAR2yRtjyT1CYhhrBJufQZRpmV-
Oz0onkowdWmR1__3IZnfSvSrkxo1RS6uM
Cognitive Biases,The Barnum Effect by Michael Gearon (2018)
https://medium.com/@michaelgearon/cognitive-biases-the-barnum-effect-
b051e7b8e029?
fbclid=IwAR33RFWcXcx7yYvwvPefpASMaERkOlzoSb8LvgNBbvkpH_4YwtO9gf
pCLE
Barnum Effect; K. D. Vohs: https://www.britannica.com/science/Barnum-Effect
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