An examination of differential item and test functioning across personality judgments

Recent research in the field of person perception suggests that the task of rating others' personality traits is more difficult for traits reflecting inner states than for traits reflecting overt behaviors. In this study, 305 college undergraduates used a Big Five instrument to provide personality ratings of themselves and their roommates. Analyses of the subsequent ratings used item response theory methods to address whether observed self-other differences in personality judgments could be interpreted as true differences in person perception (as opposed to differences resulting from statistical artifact). As predicted, mean differences in traits reflecting inner states (“low visibility” traits) did not reflect true differences, whereas mean differences in “moderate visibility” traits did reflect true differences.