Two studies examine implicit theories about the nature of personality characteristics, asking whether they are understood as underlying essences. Consistent with the hypothesis, essentialist beliefs about personality formed a coherent and replicable set. Personality characteristics differed systematically in the extent to which they were judged to be discrete, biologically based, immutable, informative, consistent across situations, and deeply inherent within the person. In Study 1, the extent to which characteristics were essentialized was positively associated with their perceived desirability, prevalence, and emotionality. In Study 2, essentialized characteristics were judged to be particularly important for defining people's identity, for forming impressions of people, and for communicating about a third person. The findings indicate that people understand some personality attributes in an essentialist fashion, that these attributes are taken to be valued elements of a shared human nature, and that they are particularly central to social identity and judgment.

People generally develop some degree of competence in general informal reasoning and argument skills, but how do they go beyond this to attain higher expertise? Ericsson has proposed that high-level expertise in a variety of domains is cultivated through a specific type of practice, referred to as "deliberate practice." Applying this framework yields the empirical hypothesis that high-level expertise in informal reasoning is the outcome of extensive, deliberate practice. This paper reports results from two studies evaluating the hypothesis. University student participants completed 12 weeks of deliberate practice in informal reasoning. Quantity of practice was recorded by computer, and additionally assessed via self-report. The hypothesis was supported: Students in both studies showed a large improvement, and practice, as measured by computer, was related to amount of improvement in informal reasoning. These findings support adopting a deliberate practice approach when attempting to teach or learn expertise in informal reasoning.