Age and gender differences in the content scales of the Minnesota Multiphasic Personality Inventory

We examined time of measurement, gender, and age differences on the nine content scales of the Minnesota Multiphasic Personality Inventory using data collected by three separate studies during the 1950s, 1960s and 1980s. No evidence was found for differences in the content scales due to time of measurement that also could not have been explained by demographic differences. Differences due to gender were found on only one of the nine scales, Masculinity-Femininity, and age differences were found on the Neuroticism, Extraversion, and Agreeableness scales. Younger men and women had significantly higher scores on the Neuroticism and Extraversion scales, and these differences were consistent in both magnitude and direction across sample and gender. Our results suggest that it is likely that openness reaches its lifetime stable level by the time typical adolescents enter college, because we found no significant age differences in intellectual interests. Neuroticism, extraversion, and agreeableness on the other hand, are likely to show instability throughout, and probably after, adolescence and early adulthood, because we found significant age differences in the content dimensions associated with these factors in separate analyses of three samples.