Is there a psychological component to frequency of urination, i.e. a stressor such as anticipation of an unpleasant event, concern about no bathroom being available? 

What can be done about this?

Stress appears to play a major role in both IC and pelvic floor dysfunction.
In terms of PFD, many patients unconsciously tighten their pelvic floor muscles at time of stress much like people who get tension headaches tighten other muscle groups.
Skipping over to bladder inflammation, an interesting study was performed last year which demonstrated the role of stress on bladder inflammation.
The study was performed on rats in which one group was stressed (immobilization for a rat is stressful) and the other group was not stressed.
I believe that they were given pina coladas and asked to relax on a sunny beach (just kidding)!
All of the animals were sacrificed and their bladders were examined.
The "stressed" animals were found to have "significant mast cell activity (mast cells are associated with inflammation) whereas very little mast cell activity was seen in the "non-stressed" group.
Many other disciplines of medicine have found body inflammation to be modulated by stress, however, this is the first report that I have seen specifically related to the effects of stress on the bladder. In a nutshell, stress appears to worsen bladder inflammation.