> As a novice to the study of the Big Five, I found that I had many misconceptions. For example, I thought that the Big Five were considered to be universal, in some sense, and not just descriptive of WEIRD college students. But in fact, it is not simply that the Big Five factors fail to fall out of the analysis of large surveys in other languages and cultures. They don’t even fall out of Big Five-specific questions administered in non-WEIRD populations (Gurven et al., 2013). Many of the concepts mentioned in the Big Five survey instruments do not even exist in non-WEIRD languages as such, particularly abstract nouns (Gurven et al., 2013). Of course a concept that does not exist across cultures could not form the basis for a universally important personality trait, as measured by language.

> Second, I imagined that the Big Five were based on large and extremely inclusive sets of survey items. I admit that I hadn’t really thought about the abstract noun “personality.” What counts as personality, and what doesn’t? Apparently, the exact nature of the questions in the survey seem to matter a great deal. Saucier & Srivastava (2015) say that the appearance of the Big Five factors “is clearly contingent on one’s variable-selection procedure,” noting that multiple particularly broad question databases have failed to produce the Big Five as the top five traits. The Big Five are not a property that emerges from all sets of questions describing humans, as the strong claim would have it, but rather from a subset of questions whose nature and selection procedure is not always clear. The consequences of this are unknown.

> Third, I’d thought that the Big Five were relatively stable across the life course; however, longitudinal studies of several cohorts of adults, born between 1914 and 1960, revealed that most traits changed over the life course in distinct patterns (Roberts et al., 2006), with social dominance (an aspect of extraversion), agreeableness, conscientiousness, and emotional stability increasing in adulthood and/or later life. One interpretation is that the positive traits identified by the Big Five are traits of adulthood, or reflections of having control over one’s environment, or something like that.

> Finally, I’d thought that the traits themselves were orthogonal, in that they were genuinely separate traits that didn’t covary much. I’d thought that this was a major focus of the factoring process, and an aspect of the traits’ specialness and validity. However, the traits covary a great deal. Lukaszewski et al. (2017) found positive mean inter-factor correlations for every country in a large international sample, and an especially high value for Tanzania, the outlier apparently driving their result (that complex societies decrease trait covariance through specialization). Nor is it unusual to find big correlations between the factors; in a large sample of twins, Shane et al. (2010) found correlations of .39 between Extraversion and Openness to Experience, and .30 between Emotional Stability and Agreeableness. Chang et al. (2012) address the problem of the non-orthogonality of the Big Five, and report that even with a methodological correction to eliminate “methods bias,” they could not eliminate correlations between many factors, suggesting some may be “redundant.”