Classic theories about cultural differences all take the same general approach. They bundle together a scattering of characteristics in one culture, then contrast them with corresponding features in another. Individualism versus collectivism, for example, describes an emphasis on individual fulfilment - American style - versus a tendency to live life through relationships, as in Hong Kong.
We all know, of course, that people do not fall into convenient, waterproof cultural categories. But we generally see such classifications as evils necessary to the western, hypothesis-testing scientific tradition. Otherwise, how could cultural theorists talk about their subject in a way that sets them apart from park-bench philosophers?
Now a new breed of cultural psychologists says a new approach has to be found, however difficult that may be. They see the old classifications as hopelessly outdated, with inadequate descriptions of today's cultural landscape.
It does not take a cross-cultural expert to notice the changes globalisation has brought to the world's cultures. Today's average professional, city-dwelling, single, thirty-something woman, for example, has as many, if not more, cultural reference points in common with her counterpart on the other side of the world as she has with her own mother. The multi-cultural settings in which such a woman typically works and lives means that she has had to develop a more flexible and expanded cultural vocabulary than did previous generations.
These days, more and larger groups of people have become cultural hybrids through travel, trade, migration, conflict and the media. Cultures were never easy to define. But they are now even harder to pin down in terms of any sort of stable experience. And, of course, there is the question of who has the right to decide what it means to be Chinese or Russian.
For cross-cultural studies to catch up with the times, the new thinking goes, theorists need to stop perpetuating the idea of culture as a single monolithic entity with a one-way influence on individuals' lives. Most people now identify with (and influence) multiple and changing sets of cultures. A Hong Kong Chinese, for example, is quite capable of operating like an individualist at work and collectively at home. So it makes sense to consider cultures as - hang on to your hat - shifting, disjointed sets of experiences.