Does self-serving bias cancel the Barnum Effect?

This study was aimed at examining 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. 27 participants filled out a personality test, then a list of traits was presented for them to rate how well each one described their own personality. A 7-point scale was used to assess the perceived accuracy for each supposed trait. The statements, demand characteristics, and genders were compared for their effects on perceived accuracy of ascribed traits. 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.