The Challenges of Investigating Causal Effects of Personality Traits

With experiments and natural experiments, you can already do a lot of research on causal effects when the cause is non psychological. But as I said, sometimes the cause is psychological, and that would be all the effects that you think when you think about effects of personality on something else. And there, it's very hard to run an experiment where you only manipulate the personality trait, let's say that you want to investigate, and not anything else of the psychological mind of that person. So basically, if your salary gets raised or something, it impacts a lot of psychological traits potentially. It just happens in nature.