ONE of the things I admire about Jonathan Bernstein's blogging on the political science of the presidential race is the determinative role he grants to media treatment of the candidates. Not because, as a member of the media, I like to feel important; if anything reporters and commentators usually like to pretend they play as small a role as possible in influencing the public's choices. Rather, it's because the analysis strips away the fiction that the media are a neutral communications channel between candidates and voters, and turns attention towards the real influence that the media's natural biases—the bias towards surprise, the bias towards cliched sentimental background stories, the bias against sophistication or complexity, etc—exercise on campaigns. This years Republican primaries have provided an excellent illustration of the power of a theory of presidential campaigns that grants media narratives a central role, because only such a theory can explain the apparently crazy swings in support we've seen amongst all the candidates except Mitt Romney.

Here's how Mr Bernstein describes what's at stake in Iowa.

Perhaps the most important point of all: It probably doesn't matter what order the top three finish in, as long as Romney, Paul, and Santorum occupy the top three spots. The biggest consequence will be that the other three campaigns will be almost certainly irreparably damaged... As for the top three, what matters isn't the results in Iowa, but how those results are spun and how they affect the coming states. Three things produce post-Iowa spin: the raw difference between expectations, generally determined by polling, and actual results; how party actors react; and media biases. The first, the expectations game, will favor Santorum, since just a week ago he was still in a jumble for fourth place. Media biases that matter favor new things, unexpected things, and keeping the contest alive for as long as possible; all of those will tend to help Santorum. Another dynamic to watch: Will Santorum's surge persuade undecided conservatives to rally around him? If so, a strong pro-Santorum spin would lead to a big bounce in New Hampshire and make him competitive in South Carolina and perhaps beyond.

The critical issue, in this account, is the directionality of the storyline taking shape in the media. Media bias towards the unexpected plays a crucial role. Things that don't play a major role in this account include candidates' stances on issues, longstanding popularity of certain candidates with particular constituencies, or even the strength of candidates' efforts to sell themselves to constituents via advertising, organisation, and so forth.

Obviously, what Mr Bernstein is talking about here is the discrete effect of the Iowa caucuses on the campaign. Candidates' positioning on issues, organisational efforts, advertising and so forth may have been significant earlier in the campaign and may resume playing a role later, once the field is winnowed down. But if you take this view, the effects of the Iowa caucus, or rather how it is spun, will dwarf any such factors; and the spin will dwarf the actual results themselves. This view comports with Nate Silver's astute remarks just before Mr Santorum began his recent surge in Iowa:

This is also a case in which the polling may actually influence voter behavior. In particular, if one of these candidates does well in the highly influential Des Moines Register poll that should be published on New Year's Eve or thereabouts, that candidate might be a pretty good bet to overperform polling as voters use that as a cue on caucus night to determine which one is most viable. I'd also pay a lot of attention to the press coverage for each candidate. Right now, for instance, there seem to be a fair number of stories about Mr. Santorum, which suggests that it is his turn to “surge” in the polls.

Overall, this emphasis on the storytelling aspect of the campaign, and on the snowballing effects of rising popularity due to positive media coverage because your popularity is rising (or the converse, on the way down) seems to me to be the only theory of the primaries compatible with a year of polls that look like this:

The media has always had an interest in shaping the story of the campaign to produce an interesting horse-race narrative. But this year's primaries seem notable for how little has stood in the way of this effort. There seems to be no fundamental constituent attachment to any candidate other than establishment favourite Mr Romney and cult-hero Mr Paul. It's a weak field, and to some extent things are always like this during the primaries. But it is striking how the evolution in sympathies resembles the narrative arc of a season of an hour-format TV drama or reality show, where writers and producers are deliberately tweaking developments to sustain audience tension. Those wild swings in voter preference are clearly predicated on weak initial attachments to the candidates. But I think they also reflect the news-media industry's increasing competence at performing its core revenue-generating function of holding public attention by creating campaign narratives with frequent twists and turns and shifting audience perspective and empathy.

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