Openness/intellect: a unique trait requires unique considerations

Openness/intellect often stands apart from the other Big Few personality traits. Here, we interrogate some of the many qualities that make openness/intellect unique. First, we describe this trait’s unique history, highlighting unresolved controversies critical to its modern interpretation. Second, we identify three major research questions where openness/intellect is unique among the Big Few: trait associations with outcomes are often moderated, it is often irrelevant to mental health, and it is the rarest target of volitional change; we develop theories to confirm and explain these phenomena. Third, we synthesize etic (imported) and emic (local) cross-cultural evidence to argue that openness/intellect is the least cross-culturally portable Big Few trait. We hypothesize that variation in individualism, looseness, and complexity modify its relevance and coherence around a potentially universal core. Throughout, we argue that understanding these unique qualities is required to cohesively interpret past openness/intellect findings and expand future research on this trait.