Norton, M. I., &Goethals, G. R. (2004). Spin (and pitch) doctors: Campaign strategies in televised political debates. Political Behavior, 26(3), 227-248.

Political campaigns frequently set low expectations (using a “low pitch”) in televised political debates to make the later claim that their candidates have done better than expected. The limited credibility of campaign aides, coupled with the fact that perception often confirms expectations, makes this strategy psychologically problematic. In Study 1, when no post-debate information was provided, lowering expectations for a candidate led to lower ratings of performance. In Study 2, when positive feedback (a post-debate “spin”) was provided after a low pitch, participants did rate performance positively, but only when the spin was supplied by a credible media source. The same strategy when used by campaign strategists adversely impacted candidates, leading to lower ratings of debate performance and network coverage.

https://doi.org/10.1023/B:POBE.0000043454.25971.6a