Long ago as time is measured in the blogosphere, Roger Morris posted a note on the topic of Learned Helplessness. You can go check out the Wikipedia entry on the topic, but in essence if you make an animal feel as if they have no control over events--if you remove their sense of personal efficacy--then the animals sink into a state indistinguishable from clinical depression.
Roger's pal Andrew Tallis (another writer, of course), pointed out that this is exactly the state of mind in which writers spend much of their time. The only control we really have is over the words on the page, and the quality of these seldom seems to have much relationship to what happens on the business side of things.
Not surprising, then, that so many writers are manic-depressive, or at the minimum strongly cyclothymic. If it weren't for the manic times, we'd never have the enthusiasm to get anything written.
But bestselling novelist Jennifer Crusie has a slightly different take on the topic. Crusie's beliefs are also based on lab research with learned helplessness:
When I read about this study, my first thought was, “Thank God, I'm not a rat.” Then I realized I was.
Crusie points out is that it's not really about control, it's about the perception of control. Simply believing makes a huge difference in outcome, even to rats.
I won't try to summarize Jenny's arguments--you should read her post on how to become Rats With Islands. But I think she's right. Our perceptions, even if delusional, can have a real and measurable effect on outcomes. And, c'mon, this should be easy. We're novelists. Delusional is our middle name.