With only 44 days until the election, pundits in the USA are baffled by the lack of inroads made by the daisy-chain bombing of conservative advertising by the Republican Super PACs.

Republican super PACs are about to face a potentially existential test of their reach and impact as the 2012 election cycle comes to a close, with their spending being closely watched as a way of answering a central question at the core of modern American politics: can an avalanche of money from outside groups move the needle in the presidential race and Senate contests across the country.

Since the spring, Republicans and Democrats have braced for the juggernaut of super PAC spending, an advertising tidal wave that was expected to swamp the messaging from the other side and quite possibly play a determinative role in deciding who will hold the presidency. Democrats have not been nearly as effective in fundraising this cycle, and have been casting jittery glances across the partisan divide.

Yet so far, the results for Republicans are muddled – at best.

In fact, this muddle shouldn’t be too surprising.

There’s several truisms in marketing. Only half of advertising works — the problem is we don’t know which half. The second truism is that advertising is a weak force, more like a mist than a jet-stream. You can’t change people’s minds with advertising.

Advertising of the kind that American Crossroads and the other Republican Super PACs are spewing out at Obama is mostly ineffective because on Obama, most people have made up their minds. The small proportion of people who’s minds have not been made up probably are non-traditional media consumers and so don’t see much of the expensive television advertising.

Additionally, advertising is mostly effective in raising awareness of a person, product or idea. When awareness is the main barrier to consumption or purchase (e.g. a new product or good being sold by a company, or a new candidate running for office), then advertising can be effective in shaping how people perceive that new person or product.

In this regard, Romney was the victim of very successful advertising. Because he was largely an unknown in 2011/12 during the Republican primaries (even though he’d run in 2007/8), his image was very vulnerable to advertising. The ads run by Newt Gingrich and Rick Perry in the primaries portrayed him as a vulture capitalist.

The Obama capitalised on this view in the electorate by running post-primary advertising early in the election cycle to solidify this perception of Romney. As an out of touch rich guy who made his money screwing over American workers.

Because Romney was “new” and most of the electorate didn’t know who he was or what he stood for, he was susceptible to this advertising.

(This is the same reason that the Swift Boat ads against John Kerry in 2004 were effective — because Kerry was a “new” candidate who was still being defined in the minds of many in the electorate.)

When people have made up their minds however, it’s very hard to change those views with advertising alone. In fact, people tend to filter out advertising that contradicts their existing views and only take on ads that reinforce their existing views.

For Romney and the Republicans, this is bad, for two reasons.

Firstly, it means it will be difficult for Romney to reshape the views about him held by voters.

Secondly, it means that most of the spending by the Republican Super PACs won’t be enormously effective in changing the established views of Obama.

This doesn’t mean that the onslaught of advertising by Karl Rove’s American Crossroads and its kin can’t influence the election. It may. When over $600 million has been spent with over a month until Election Day, it’s possible that the “tsunami” of television ads will change the views of enough people to win it for Romney.

But it also shows why the Obama campaign has pumped so much money and resources into field organising and face-to-face campaigning. (And there’s really only one pro-Republican group that can go toe-to-toe with Democratic field organising: evangelical churches.)

Because the research demonstrates that the most effective way to change someone’s view is through a person-to-person conversation.