I'd say there's even a third option, the causality runs back AND forth (both good thoughts can lead to good outcomes as well as bad outcomes can lead to bad thoughts and vice a versa)

Even in this third option there exist an infinite number of sub options on a gradient (where each direction carries more or less weight).

Of course, any meaningful conversation can only happen after definitions (like what is pessimistic) are agreed upon. I for one don't agree with the definition of pessimism as defined by the study.