The big five traits- that I like to remember with the very Canadian mnemonic of "CANOE" are Conscientiousness, Agreeableness, Neuroticism, Openness to Experience and Extraversion. A couple of things are important to note, however, in terms of the traits measured in this study. First, Neuroticism is also often phrased and measured as its opposite, "Emotional Stability" which is expressing calmness and freedom for persistent emotions. The researchers used this in their study as opposed to Neuroticism. Second, the fifth factor in the model as it has been researched (not how we remember it with CANOE) is the Openness to Experience factor. This is interpreted differently in different studies and cultures.
In this study, as is typical in many European studies, the recearchers defined and measured it as Autonomy which reflects an individual's tendencies to form his or her own opinions and take independent decisions.