The excitement / calm signal commonly varied, whereas the engagement/disinterest and meditation signals were harder to change.
Preparing images for this blog post (typical for random task)
The engagement / disinterest signal seemed to require a sustained change in attention for an extended period of time, which was sometimes accompanied by a clear change in the excitement / calm signal (for example, see the slight long-term increase in the image below).
I wasn't really able to see any clear peaks in the meditation signal but I could see a decrease in the engagement signal when trying to relax (for example, see the long-term change in the image below).
Listening to music with eyes closed
In short, I think the engagement / disinterest signature was the most accurate, the excitement / calm signature may be too sensitive, and the meditation signature may not be sensitive enough.