You wouldn't think tarantulas and Toilet Duck bore any relation to the Referendum but that's because you're not thinking rationally, stupid!

Very few of us are, according to Mind Games (BBC2). When making political decisions we might kid ourselves we're casting a vote based on facts and logic but science is proving that, when it comes to politics, our hearts rule our heads. This supposed supremacy of the heart is vitally important as the indyref campaign is utterly pinned to emotion, with one side working through hope and the other through fear.

The measuring of emotional responses to politics first arose in the 2004 Bush v Kerry presidential race. Voters were given MRI scans to see how their brains were reacting to political messages. The results were grim, suggesting there was 'no reasoning going on at all.' People simply wanted to support their man and were scarcely troubled by what he actually said. On being shown contradictory statements from the candidate their support for him didn't waver. Instead, 'people started to validate the conclusions they wanted to come to.' So the voters had made their minds up before hearing any arguments and just shaped everything to fit their expectations. Emotion - or perhaps you might call it prejudice or plain old stupidity - was triumphing over reason.

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The programme made it clear that 'the heart is in the driving seat more than people imagine' and Dr Rob Johns of the University of Essex supported this. He said 'rational calculation is incredibly arduous' and, in the indyref campaign, he cannot believe voters will sit down with graphs and calculators, spending weeks adding up the costs and benefits of independence. The heart will always win over the Excel spreadsheet.

Professor Laura Cram of Edinburgh University also agreed on the primacy of emotion in voting. Her research has shown that a subject's reaction to a political topic will vary if they're shown a tiny flicker of a St Andrew's or St George's flag. You may insist you're not moved by silly symbols but your subconscious will beg to differ.

So, are we helpless in determining how to vote? Professor Cram says no: we decide for ourselves, but our choice is not as free as we think. There is a barrage of emotional, environmental and neurological factors pressing on us when we make a decision, even though we're hardly aware of them.

This must be good news for politicians, if we're susceptible to mind games, tricks and tiny little flags. Are they exploiting this in the indyref campaign?

Certainly. The unique prominence of emotion in the campaign is being utilised. The Yes campaign are based on the emotion of hope - it could hardly be otherwise; no-one knows what an independent Scotland would be like so they have to go with hope and optimism, and their campaign is based around that. We were shown how Yes use 'Ground War' tactics: people on the doorstep, badges, balloons and folksy public meetings. They've gone back to old fashioned campaign methods, whereas No are more restrained. Their relatively aloof style suits their 'emotion', which is one of caution and wariness. They have opted for 'Air War' tactics, preferring to use their influence with certain sections of the media. Both sides have chosen campaign styles to match the emotion they advocate: No are the careful, sombre men in suits and Yes are the chirpy chappies on the doorstep.

It was all quite grim. In amongst the science and the brain scans and the data analysis was the impression that, to politicians, we're nothing but rats in a maze, and they spend their days wondering 'how can we get these rats to snuffle their way to our piece of cheese?'

But perhaps it's nothing new. Presenter Ken Macdonald remarked that supermarkets have been doing this for years: working out ways to guide and sway us, to make us buy a certain thing, linger in a certain aisle, touch a certain product. There's a reason why you always enter a supermarket to be faced with fresh fruit, and never toilet rolls. We are being shaped and worked and we scarcely realise it. The only difference is that politicians have now caught up and bagged themselves an MRI scanner. I wonder if it gets passed around between them, with nippy texts flying from one Blair to the other 'uv had it 4 ages m8. Our turn next wk. Lol.'

The least scientific, though most entertaining, segment of the programme was a light-hearted experiment done in the foyer of BBC Scotland. Staff on their lunch break were shown pictures of bristly tarantulas and asked to rate their fear on a scale of 1 to 10. They then had to indicate how they'd vote in September. Results showed that those who reacted most strongly to the fear stimulus were most likely to vote no, suggesting yet again that your vote isn't wholly based on logic but connected to your childhood and learned responses to fear. Therefore, the No campaign are correct to focus on fear whilst Yes will obviously seek to combat that with a focus on hope.

But what of the undecided voters - those who neither shriek nor shrug at beasties? Are they out there, unfettered and brave, making free, logical choices? We can only hope so as this programme suggests the Referendum is in their cool hands.