There is (supposedly) some truth to that in the sense that the story is people vote for the more optimistic candidate, or something. I wish I could remember what the word was.
For Presidential Candidates, Optimism Appears a Winner
By DANIEL GOLEMAN
Published: May 08, 1988
Psychologists have their own view of American Presidential elections. For some, the outcome in November hinges on optimism.
Psychologists at the University of Pennsylvania have measured what they call the level of pessimism in the nomination acceptance speeches by candidates in 1948 and in every succeeding Presidential campaign. They found that, with one exception, the more optimistic candidate won.
http://www.nytimes.com/1988/05/08/us/for-presidential-candidates-optimism-appears-a-winner.html