We were discussing a creative idea for a food brand the other day. The brand manager was unhappy. Volume potential lay in encouraging use by families, so he was worried that the proposed script showed a young couple tucking into the food with friends. This is a classic example of the myth of 'consumer identification', ie to appeal to certain people, we should feature said people. The result: heated debate at script and casting meetings, and ads featuring ad world's version of 'normal people' – people almost like us, but with better hair, make-up and fridge cleanliness. Grrrrr…

This myth seems like common sense. So what's the problem? First, people don't like seeing themselves in ads, whatever they say in pre-testing. If you ask people in research, 'who should feature in ads targeting you?', they will tend to say 'people like us'. But that doesn't mean this is what we should do. M&S found this to its cost a few years ago, when it featured a naked 'ordinary' woman in a TV ad (described memorably by one City analyst as 'the fat-bird-running-up-the-hill ad'). It didn't take long for this brief foray into real people to be replaced by a highly successful campaign featuring Twiggy, Dannii Minogue and beautiful models. If you want to portray the public, warts and all, do it at one step removed. Animal characters, for example, are fantastic for this. For many years, the famous PG Tips tea ads in the UK featured chimps dressed as humans displaying all manner of snobbery, ignorance and intolerance, which would be inconceivable if played by people.

The bigger reason why this identification concern is unfounded is that people don't identify with what people look like – they identify with their hopes, problems and challenges. It's why Shakespeare's plays are still so relevant today. As Jeremy Bullmore put it: "You don't have to be black to identify with Othello. Just jealous."

A few years ago, we worked on an ad for red meat, which featured a sweet couple in their eighties, celebrating their wedding anniversary with a steak dinner. It turned out to be by far the most successful ad of the long-running campaign on every level, from tracking to sales. Young people loved it even more than older people. You didn't need to be 80 to 'identify' with the couple. Instead, everyone identified with the emotions of celebrating a lifelong, happy marriage.

Why has The King's Speech been such a successful film? Not because we are all kings. Or have speech impediments. Colin Firth doesn't look remotely like King George VI. Instead, we all identify with the emotional themes – social exclusion, shame and the challenge of overcoming obstacles with the support of a friend. When people in research suggest an ad's characters should be more 'like them', it's usually a symptom of a wider problem – the communication not resonating emotionally. Not identifying with the casting is just a convenient, post-rationalised thing for people to say.

You might be wondering about the Dove Campaign for Real Beauty at this point. This, of course, was Unilever's famous example of using 'real women' in a very successful campaign. Is this an exception to the identification myth. 'Talking to the planner involved, it seems not. Although the idea did feature 'real women', the key to the campaign's success was the way it worked emotionally. Women loved not so much the 'realistic' portrayal as what the campaign stood for – the idea that every woman has her own beauty – and its attack on the distortions of the beauty industry. The 'real women' in the ads were primarily shorthand for this bigger thought.

So what seems to happen is that the people we feature signal things about the brand, not the user. Yorkie (a chunky chocolate bar) typically featured blokes driving juggernauts in its ads. When it launched a new campaign with the line 'It's not for girls', female journalists sniped and sales increased. But sales increased as much among women, who wanted a chunky, rib-sticking chocolate bar, as men. The brand was manly, not necessarily the eater.

So when you next find yourself debating the people in your ad, remember Othello.

This article originally appeared in the May 2011 issue of Admap. Click here for subscription information.