"Positive" results ...

This paper caught my eye a while back: "Positive" Results Increase Down the Hierarchy of the Sciences (2010). To quote the abstract:

If the hierarchy hypothesis is correct, then researchers in "softer" sciences should have fewer constraints to their conscious and unconscious biases, and therefore report more positive outcomes. Results confirmed the predictions at all levels considered: discipline, domain and methodology broadly defined.

I wonder where the authors would classify this work on the soft/hard scale?