Does self-serving bias cancel the Barnum effect

Social Behavior and Personality, 2002 by MacDonald, Dany J, Standing, Lionel G

This study examines whether individuals believe in the reality of positive personality traits more readily than negative traits, when these are falsely ascribed to them in a bogus feedback situation. Twenty-seven participants first filled out a personality test, then a list of traits (positive, negative and neutral) was presented for them to rate how well each one described their own personality. A seven-point scale was used to assess the perceived accuracy for each supposed trait. The three types of statements, demand characteristics, and genders were compared for their effects on perceived accuracy of ascribed traits, using a 3 x 2 x 2 mixed ANOVA. The results indicate that the type of trait presented to the participant affected the rating in relative terms, according to the principle of self-serving bias, whereas gender and demand characteristics showed no significant effect. It appears that the self-serving bias is powerful enough to cancel the usual Barnum effect, in which subjects typically show marked gullibility for statements about themselves.

Past studies of the `Barnum effect' have consistently demonstrated that individuals have a strong tendency to accept bogus feedback of personality tests (Foyer, 1949; Layne, 1998; Standing & Keays, 1986), habitually displaying a high level of gullibility. This problem is of interest since it can give an insight into the ways people perceive themselves. The latter two studies mentioned above used computer assessments of personality traits to demonstrate that individuals will have a high tendency to accept positive statements about themselves, even if these statements are inaccurate.

The main interest in the present study is to determine, using a computerized personality test, whether or not people will accept positive statements, but reject negative statements about themselves, so as to test for a relationship between the Barnum effect and the phenomenon of self-serving bias. According to many studies, people show a pervasive tendency towards self-serving bias: to perceive themselves favorably, no matter what the objective evidence (e.g., Johnson, Gain, Falke, Hayman, & Perillo, 1985; Ross & Sicoly, 1979). Can this tendency cancel out the usual Barnum process when the two processes are pitted in opposition? Typical studies of the Barnum effect have used traits which are essentially positive, although Snyder and Shenkel (1976), for example, have found that people more readily accept favorable as compared to unfavorable Rorschach-- based statements about themselves, whereas ratings for other people's traits did not show this bias.

In the present study, a high level of acceptance for positive traits only would indicate that self-serving bias is more powerful than the Barnum effect and - in effect - can replace it. Conversely, a high rating for both negative and positive traits would suggest that the Barnum effect is present, and eliminates the usual self-serving bias. Neutral traits are also used in this study.

Gender may be relevant to the Barnum effect. Piper-Terry and Downey (1998) found that females described their friends' feedback on bogus personality tests as being more accurate, a trend which merits further investigation.

The present study raises three questions. The first involves the difference in subjects' acceptance of positive, negative and neutral statements. The second question concerns gender differences, and the third question examines the demand characteristics displayed by the participants (Orne, 1962). The hypothesis for the first question is that there will be a significant difference between the positive and negative statements. For the second question, the possibility of a gender difference is open. For the third question, demand characteristics are not predicted to show an effect, as it is expected that few participants can guess the main experimental hypothesis.

METHOD

PARTICIPANTS

The study used 27 undergraduate psychology students, solicited through an email request. The participants were volunteers, and were treated according to APA ethical guidelines.

MATERIALS

An abbreviated version of the Eysenck Personality Inventory Form B was administered to the participants in order to create the Barnum effect. A list of positive, negative and neutral traits, made by the experimenters on the basis of a pretest, was used as a rating measure of the respondents' traits. The list of traits included seven positive ones (Generous, Cheerful, Ambitious, Assertive, Affectionate, Optimistic and Persistent), seven negative traits (Tense, Impulsive, Moody, Fearful, Jealous, Cynical, and Nervous), and four neutral traits (Worldly, Serious, Venturesome and Sensation Seeking). For each trait, the written instructions asked the subject, "Please rate to which degree you believe yourself to have this trait. 1 would imply that you do not agree with this trait, whereas 7 would imply that you strongly agree with the trait."

A laptop computer and a printer were used to increase the plausibility of the situation. A post-experimental questionnaire was also used in order to determine whether or not the participants displayed demand characteristics (according to whether they correctly identified the main hypothesis of the study). A consent form was given to the subject at the beginning of the experiment and a debriefing was provided at the end of the study.