If the recession really is over - and few now doubt it - advertisers face the challenge of directing pent- up demand towards their products. The theory is that to maximise consumer spending, ads will have to emphasise the twin themes of reason and reassurance. 'Don't sell sizzle, sell security,' says Jim Murphy, associate director of the Henley Centre for Forecasting. Why? For those who like their decades summed up in one adjective, preferably alliterative, we are living in the nervy Nineties. The cautious consumer is in charge.
The argument is based partly on the legacy of a downturn, the victims of which have included the better-off. The slump has led to wariness about debt, middle-class unemployment, a loss of confidence in house prices, and reduced expectations of income growth. More fundamental developments include fragmenting family structures, less job security, more frequent career changes and a diminishing faith in the welfare state.
'When you stack up these factors,' argues Mr Murphy, 'it is foolish to think consumer behaviour will revert to the style of the Eighties. A change of atmosphere is bearing down on much marketing activity. People are becoming more hesitant and cautious about their future.
'Increasingly, the function of marketing will be to make us feel more comfortable about making choices, taking risks and indulging ourselves. Consumers will have a greater need for rational explanations of why they buy things.'
This view is backed up by extensive research produced earlier this year by one of the country's major agencies, Abbott Mead Vickers BBDO. According to Drusilla Gabbott, the board account planner at AMV who organised the study: 'There is a profound consumer attitude shift. This will liberate agencies from the pressure to try to sell products on the basis of warm, slushy feelings. We've always been the sort of agency that sells on rational benefits, and Nineties attitudes have moved our way.
'You can't say functional benefits are everything in advertising, as each product category is different, but some generalisations can be made. People are frightened and they want to spend their money wisely.'
While some product areas - such as perfumes - will doubtless remain immune, in others change is already apparent. Since the Eighties, car advertising has seen a dramatic shift away from images of excitement and glamour towards the making of specific claims, especially about safety, reliability and durability. The archetypal car commercial now features air bags instead of burning fields.
For Ms Gabbott the year's most talked about ads, the supermodel ones for the Vauxhall Corsa, are a good example of her thesis. They are simply an elaborate way to draw attention to specific product benefits, such as capacity, safety features and anti-theft devices.
Ironically, the obvious counter- example might seem to be Volvo, a long-standing AMV client with a unique reputation for safety, established through years of distinctive advertising. At a time last year when BMW and Audi had started to compete for its safety territory, the Swedish company caused widespread astonishment when it undertook an apparent reversal in strategy. The TV commercial for the 850 saloon, which showed the car metamorphosing into a galloping horse against the backdrop of the Australian outback, was an uncharacteristic appeal to driver excitement.
This now seems to have been a blip. The ad launched last month for the 850 estate reassuringly extols the virtues of its side-impact protection system and confirms that Volvo recognises that now is not the time to risk surrendering its safety image.
There are other areas where the required shift has a long way to go. According to Ms Gabbott, the biggest opportunity is in marketing financial services. Companies should spend less time on their corporate images, especially when their desired image cannot be reconciled with public perceptions, and more on giving specific details of their services.
A similar view is taken by Mike Fredman, chairman of Bates Direct Communications, a BSB Dorland subsidiary. He says: 'Research shows 62 per cent of people do not know what interest they are being paid on their savings. Too much money in financial advertising is spent on telling people 'We're big, friendly and wonderful'. It's not on any more. People want a specific proposition, so they can understand what's in it for them.'
Others take a different view of what makes advertising effective. John Hegarty, creative director of Bartle Bogle Hegarty and the man behind the Levi's campaign and other trend-setting Eighties advertising, says: 'I'm sceptical of claims that 'the Eighties were like this, the Nineties are like that'. Trying to go with the flow is poor marketing. Great advertising lives beyond fashion. Our work for Haagen-Dazs ice-cream has made its own rules. It looked like an Eighties product, but has been hugely successful in the Nineties.'
He rejects the idea that consumer behaviour is becoming more careful and rational: 'Human beings are nine-tenths emotional. The heart rules the head, it always has and always will. Ultimately, emotion is what sells.'
The debate is not only about different advertising styles, but also whether people whose job it is to sell things should be soothsayers trying to foresee the spirit of an age. Chris Powell, chief executive of BMP DDB Needham, dismisses would-be advertising gurus who 'believe they can predict broad social attitudes for up to 10 years ahead'. He calls it 'faddism' and says: 'One week they say something, then next week they say something else.'
It was, after all, a report from the Henley Centre in 1989 that loudly proclaimed the short-lived notion of the 'caring Nineties'. Nevertheless some social trends are real, if not always easy to discern. Will the Nineties stay nervy to the end? Or will the advertising gurus have to find a new label for the end of the decade?