Do personality traits conform to lists or hierarchies?

• Do personality traits mostly conform to lists or hierarchies?
• Data: adjective ratings and scores on basic personality inventory scales.
• Goldberg’s “bass-ackwards” method applied for series of 1–12 factors.
• List- rather than hierarchy-type structure predominantly observed.

Are personality traits mostly related to one another in hierarchical fashion, or as a simple list? Does extracting an additional personality factor in a factor analysis tend to subdivide an existing factor, or does it just add a new one? Goldberg’s “bass-ackwards” method was used to address this question, based on rotations of 1–12 factors. Two sets of data were employed: ratings by 320 undergraduates using 435 personality-descriptive adjectives, and 512 Oregon community members’ responses to 184 scales from 8 personality inventories. In both, the view was supported that personality trait structure tends not to be strongly hierarchical: allowing an additional dimension usually resulted in a new substantive dimension rather than in the splitting of an old one, and once traits emerged they tended to persist.